Voltage to PWM chip (similar to class D)?

[rickman]

On 5/30/2014 7:59 PM, Joerg wrote:

Stopband is a pretty gradual thing when you can't go past 3rd order on
the output filter. This application is sensitive to noise because the
load is super fast.

I guess I'm not really following all this. You have a control circuit
that is not easy to do with analog chips and yet you don't want to use a
digital control. From the bits and pieces I am seeing I believe a
classic ADC-DSP-DAC would suit this problem very well. Forget the silly
PWM thing and all the goofy filtering problems. I only call it silly
because in this design it doesn't seem to fit very well. With a pretty
basic digital path you could do the whole thing in one chip even. I
believe ADI makes some devices intended for exactly this although I've
never used them.

Or maybe I'm still not following what you are trying to do.

I could recommend a chip that could handle this *very* easily, but if
you think an FPGA is hard to program, this would blow your mind!

--

Rick

 

[Joerg]

rickman wrote:

On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:

I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.


We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.

Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.

It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.

If you need a 20 year production life, what parts *can* you use? ...


Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.

Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol

And I might. Plus opamps/comparators.

... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.

I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.

There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.

... Does LTI give any assurance of a 20 year product life?


LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.

Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.

... What MCUs or DSPs are
around after 20 years? ...


8051. That's why this is one of my favorites.

Yes, I knew you would mention that one. But that is the *only* one and
even then not all the parts are pin compatible.

Got to stay with multi-sorce packages like 44 QFP.

So if you need some *real* processing capability, something that would
be the equivalent of a *real* MCU or FPGA, what would you use? Unless
they are making a 100 MHz 8051 I think you are pretty limited by that
choice.

They _are_ making 100MHz 8051. No kidding. If it ain't got enough horses
use a 2nd one

... Of these parts, I would be much less worried
about FPGAs being around in 20 years although that is likely stretching
it. If you need 30 years... I guess I don't know, I only been in the
business for 40 years and don't expect to be around myself for another
30... in the large sense.


Some of my designs have already celebrated their 20th in production and
no end in sight.

Yes, if you are using stuff like 2N2222 transistors, sure. But I am
talking about something of similar complexity to an FPGA, DSP or modern
MCU. Otherwise just keep using the stuff you have been using.

This is one reason why I try to keep things simple. Many jobs that are
done with a DSP can be done without. But not all of them, of course. Of
course, for me that's easier to say than probably for you because I do
mostly analog stuff. Sometimes it's the whole architecture though and
then one of my fuirst questions to the client is about parts sourcuiing
and longevity.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

rickman wrote:

On 5/30/2014 7:59 PM, Joerg wrote:

Stopband is a pretty gradual thing when you can't go past 3rd order on
the output filter. This application is sensitive to noise because the
load is super fast.

I guess I'm not really following all this. You have a control circuit
that is not easy to do with analog chips and yet you don't want to use a
digital control. From the bits and pieces I am seeing I believe a
classic ADC-DSP-DAC would suit this problem very well. ...

Generating a PWM stream with down to 1nsec granularity that way would be
increadibly power intense and expensive.

... Forget the silly
PWM thing and all the goofy filtering problems. I only call it silly
because in this design it doesn't seem to fit very well. With a pretty
basic digital path you could do the whole thing in one chip even. I
believe ADI makes some devices intended for exactly this although I've
never used them.

I haven't found any, only delta-sigma which doesn't fit too well here.

Or maybe I'm still not following what you are trying to do.

I could recommend a chip that could handle this *very* easily, but if
you think an FPGA is hard to program, this would blow your mind!

I am pretty sure there are FPGA that can do this but not alone, they
must have an ADC up front because the control is analog (not my choice,
it's a requirement).

It isn't a problem at all doing this analog. I can use any old PWM chip
or one of those TimerBlox from LTC, hang an error compensation loop
around it and call it a day. Two ICs and a sprinkling of discretes. And
I will do that if there aren't any suitable single-chip class-D audio
solutions.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

josephkk wrote:

On Fri, 30 May 2014 09:47:56 -0700, Joerg <invalid@invalid.invalid> wrote:

Tim Wescott wrote:
On Thu, 29 May 2014 14:20:26 -0700, Joerg wrote:

Folks,

Does anyone know an IC that can turn a control voltage into PWM and can
handle PWM frequencies in the 50-1000kHz range? Similar to a class D
driver but has to go down to DC. The changes in control would be
restricted to the audio spectrum below 15kHz.

The LTC6992 does this nicely but isn't precise enough. Same with
555-style timers or switcher chips. I am looking for better 1% and
ideally a lot better, including nonlinearity, drift, warts and all. A uC
is not suitable either because it should be simple and I need very fine
control granularity, down to around 0.1%.

Can't use short-lived consumer chips for radios and TV sets and such.
A 555 or other teeny thing wrapped with integrating feedback, to hold the
average at precisely what you want? It kinda violates your "one chip"
desire, but at least it can be done with a minimum of small parts.

I am going to do something like that (but probably not with a 555) if
nothing single-chip comes up. That's the reason for this thread, to see
if there isn't anything out there. I mean, every class-D amp must have a
super-linear PWM generator. It's just that most have the power stages
built in (would be ok, can be left idle) and have lousy or no DC
performance (would not be ok).


Ok a weird question: Does the response need to be 0.1% for any step size
at 15 kHz? ...

Nope :-(

... Can it be "slew rate limited" a bit to get to 0.1% for a large
step; to like 900 Hz?

Unfortunately that would put a serious crimp into the versatility of the
product.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

josephkk wrote:

On Thu, 29 May 2014 14:20:26 -0700, Joerg <invalid@invalid.invalid> wrote:

Folks,

Does anyone know an IC that can turn a control voltage into PWM and can
handle PWM frequencies in the 50-1000kHz range? Similar to a class D
driver but has to go down to DC. The changes in control would be
restricted to the audio spectrum below 15kHz.

The LTC6992 does this nicely but isn't precise enough. Same with
555-style timers or switcher chips. I am looking for better 1% and
ideally a lot better, including nonlinearity, drift, warts and all. A uC
is not suitable either because it should be simple and I need very fine
control granularity, down to around 0.1%.

Can't use short-lived consumer chips for radios and TV sets and such.

The only things that i have seen that are even close were V to F
converters. And they did DC to a few hundred Hz on the input spectrum.

Yup, I've used them but they aren't precise enough. Also, they don't
work well for PWM, just for V/F anf F/V.

Maybe some audiophool Class D amplifier IC.

T'is exactly what I am looking for and why I posted here

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Lasse Langwadt Christense]

Den lřrdag den 31. maj 2014 16.21.47 UTC+2 skrev Joerg:

rickman wrote:

On 5/30/2014 7:59 PM, Joerg wrote:



Stopband is a pretty gradual thing when you can't go past 3rd order on

the output filter. This application is sensitive to noise because the

load is super fast.



I guess I'm not really following all this. You have a control circuit

that is not easy to do with analog chips and yet you don't want to use a

digital control. From the bits and pieces I am seeing I believe a

classic ADC-DSP-DAC would suit this problem very well. ...





Generating a PWM stream with down to 1nsec granularity that way would be

increadibly power intense and expensive.

the dsPIC33 has ~1ns resolution PWM and a 10 bit 2Msps ADC, $1.69 if you buy 1000


-Lasse

 

On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid>
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:

I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.


We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.

Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.


It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.

If you think that money (and time) invested has nothing to do with
"risk", perhaps. That's a rather Democratic view of economics,
though.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.

Crap! That must have been 1960. ;-)

If you need a 20 year production life, what parts *can* you use? ...


Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.

Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol


And I might. Plus opamps/comparators.


... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.


I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.

The 8051s of today aren't your grandfather's 8051s, either. I'm
trying to push the ARM-Mn as the microcontroller for the future. We
just switched to AVRs but there are a lot more choices in ARMs. If
the code is written properly, porting to a new processor isn't a big
deal.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.


There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.

Use Automotive parts. They're committed to making them for at least a
decade. Of course that assumes you don't pick one that's already been
around two. ;-)

... Does LTI give any assurance of a 20 year product life?


LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.

Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?


I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.

ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.

<...>

 

[Joerg]

krw@attt.bizz wrote:

On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:
I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.

We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.
Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.

It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.

If you think that money (and time) invested has nothing to do with
"risk", perhaps. That's a rather Democratic view of economics,
though.

Huh? Going ASIC took a lot of risk out of this process. Instead of
depending on an FPGA manufacturer who is depending on a foundry we were
then only depending on a foundry.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.

Crap! That must have been 1960. ;-)

Yeah, I was surprised myself. But all the places we are using for the
various fab steps consider that standard fare.

If you need a 20 year production life, what parts *can* you use? ...

Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.
Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol

And I might. Plus opamps/comparators.


... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.

I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.

The 8051s of today aren't your grandfather's 8051s, either. I'm
trying to push the ARM-Mn as the microcontroller for the future. We
just switched to AVRs but there are a lot more choices in ARMs. If
the code is written properly, porting to a new processor isn't a big
deal.

Yes, but it's a re-layout and in many regulated environments you must go
through the whole big validation process again.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.

There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.

Use Automotive parts. They're committed to making them for at least a
decade. Of course that assumes you don't pick one that's already been
around two. ;-)

Or was specifically made for a car series that then gets discontinued in
two years. That is a problem with parts for consumer electronics sucha s
TV sets. I never use them anymore.

... Does LTI give any assurance of a 20 year product life?

LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.
Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.

ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.

Oh yeah, some clients have been stung, big time. OTOH that has brought
me several "design-out" assignments that then turned into longterm
client relationships. One lasted all the way until the company owner died.

--
Regards, Joerg

http://www.analogconsultants.com/

 

On Sat, 31 May 2014 12:36:07 -0700, Joerg <invalid@invalid.invalid>
wrote:

krw@attt.bizz wrote:
On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:
I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.

We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.
Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.

It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.

If you think that money (and time) invested has nothing to do with
"risk", perhaps. That's a rather Democratic view of economics,
though.


Huh? Going ASIC took a lot of risk out of this process. Instead of
depending on an FPGA manufacturer who is depending on a foundry we were
then only depending on a foundry.

You don't think significant NRE *ADDED* risk? You have a real funny
CFO.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.

Crap! That must have been 1960. ;-)


Yeah, I was surprised myself. But all the places we are using for the
various fab steps consider that standard fare.

Seriously, I thought everyone had gone to at least 6" wafers decades
back. It's been over a decade since the digital guys went to 12"
(300mm). Of course, 8" are still common for jelly beans.

If you need a 20 year production life, what parts *can* you use? ...

Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.
Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol

And I might. Plus opamps/comparators.


... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.

I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.

The 8051s of today aren't your grandfather's 8051s, either. I'm
trying to push the ARM-Mn as the microcontroller for the future. We
just switched to AVRs but there are a lot more choices in ARMs. If
the code is written properly, porting to a new processor isn't a big
deal.


Yes, but it's a re-layout and in many regulated environments you must go
through the whole big validation process again.

Not just layout but does anyone make a 12-clock, 12MHz 8051 anymore?
ARM *is* the way forward.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.

There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.

Use Automotive parts. They're committed to making them for at least a
decade. Of course that assumes you don't pick one that's already been
around two. ;-)


Or was specifically made for a car series that then gets discontinued in
two years. That is a problem with parts for consumer electronics sucha s
TV sets. I never use them anymore.

Name one (an ASSP, not an ASIC). Even if it's only in one car series,
it'll have at least a 10yr life, though if you only want one don't
count on any part being available in a decade.

... Does LTI give any assurance of a 20 year product life?

LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.
Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.

ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.


Oh yeah, some clients have been stung, big time. OTOH that has brought
me several "design-out" assignments that then turned into longterm
client relationships. One lasted all the way until the company owner died.

The company died with him? Of course the federal government wants
that to happen but it is still pretty poor planning.

 

[Joerg]

krw@attt.bizz wrote:

On Sat, 31 May 2014 12:36:07 -0700, Joerg <invalid@invalid.invalid
wrote:

krw@attt.bizz wrote:
On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:
I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.

We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.
Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.

It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.
If you think that money (and time) invested has nothing to do with
"risk", perhaps. That's a rather Democratic view of economics,
though.

Huh? Going ASIC took a lot of risk out of this process. Instead of
depending on an FPGA manufacturer who is depending on a foundry we were
then only depending on a foundry.

You don't think significant NRE *ADDED* risk? You have a real funny
CFO.

Pouring it into an ASIC was not very onerous in terms of NRE. Plus we
could easily amortize it. It paid for itself in a jiffy anyhow because
the ASICs were much less expensive.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.
Crap! That must have been 1960. ;-)

Yeah, I was surprised myself. But all the places we are using for the
various fab steps consider that standard fare.

Seriously, I thought everyone had gone to at least 6" wafers decades
back. It's been over a decade since the digital guys went to 12"
(300mm). Of course, 8" are still common for jelly beans.

That's what I thought as well. Until the end of last year. To me that
was like going to a car dealer and finding brand new 1956 Bel Airs.

If you need a 20 year production life, what parts *can* you use? ...
Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.
Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol
And I might. Plus opamps/comparators.


... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.

I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.
The 8051s of today aren't your grandfather's 8051s, either. I'm
trying to push the ARM-Mn as the microcontroller for the future. We
just switched to AVRs but there are a lot more choices in ARMs. If
the code is written properly, porting to a new processor isn't a big
deal.

Yes, but it's a re-layout and in many regulated environments you must go
through the whole big validation process again.

Not just layout but does anyone make a 12-clock, 12MHz 8051 anymore?

You can but there is no law against using a 25MHz or whatever version
with a 12MHz clock.

ARM *is* the way forward.

I might use my first one this year. Pondering which one to pick, one
that has good audio connectivity. Still got lots of time, maybe it'll be
the M4F series from TI. I was eyeing an AD Sharc but after a sobering
awakening with their seemingly outsourced "support" I decided not to.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.

There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.
Use Automotive parts. They're committed to making them for at least a
decade. Of course that assumes you don't pick one that's already been
around two. ;-)

Or was specifically made for a car series that then gets discontinued in
two years. That is a problem with parts for consumer electronics sucha s
TV sets. I never use them anymore.

Name one (an ASSP, not an ASIC). Even if it's only in one car series,
it'll have at least a 10yr life, though if you only want one don't
count on any part being available in a decade.

I don't remember, too long ago. Mostly TAA, TBA and TCA series chips. I
haven't used them but clients have and then got burned.

... Does LTI give any assurance of a 20 year product life?
LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.
Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.
ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.

Oh yeah, some clients have been stung, big time. OTOH that has brought
me several "design-out" assignments that then turned into longterm
client relationships. One lasted all the way until the company owner died.

The company died with him? ...

Kind of. His widow ran it for another year or two. It is good not to
make any drastic asset changes right after a spouse passed away but
eventually she sold the company. It was a smart move on her part.

... Of course the federal government wants
that to happen but it is still pretty poor planning.

You can't always avoid it. Sam's Town was a local Western style
entertainment city right in our village (Cameron Park). Mostly for kids
and many Bay Area folks fondly remember that from trips to Lake Tahoe,
when dad pointed his Studebaker towards the off ramp. Death taxes killed
it, along with over 150 well paying jobs. Those jobs never came back and
the place was bulldozed. Dems do not understand this stuff.

--
Regards, Joerg

http://www.analogconsultants.com/

 

On Sat, 31 May 2014 13:24:16 -0700, Joerg <invalid@invalid.invalid>
wrote:

krw@attt.bizz wrote:
On Sat, 31 May 2014 12:36:07 -0700, Joerg <invalid@invalid.invalid
wrote:

krw@attt.bizz wrote:
On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:
I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.

We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.
Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.

It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.
If you think that money (and time) invested has nothing to do with
"risk", perhaps. That's a rather Democratic view of economics,
though.

Huh? Going ASIC took a lot of risk out of this process. Instead of
depending on an FPGA manufacturer who is depending on a foundry we were
then only depending on a foundry.

You don't think significant NRE *ADDED* risk? You have a real funny
CFO.


Pouring it into an ASIC was not very onerous in terms of NRE. Plus we
could easily amortize it. It paid for itself in a jiffy anyhow because
the ASICs were much less expensive.

It had to have been a trivial part. ASICs are unaffordable for all
but a few applications. Really, they're only interesting when there
is no other choice (rather the same for FPGAs but on a whole different
level).

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.
Crap! That must have been 1960. ;-)

Yeah, I was surprised myself. But all the places we are using for the
various fab steps consider that standard fare.

Seriously, I thought everyone had gone to at least 6" wafers decades
back. It's been over a decade since the digital guys went to 12"
(300mm). Of course, 8" are still common for jelly beans.


That's what I thought as well. Until the end of last year. To me that
was like going to a car dealer and finding brand new 1956 Bel Airs.

OK, now it's clear that you're been working in Cuba. ;-)

If you need a 20 year production life, what parts *can* you use? ...
Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.
Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol
And I might. Plus opamps/comparators.


... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.

I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.
The 8051s of today aren't your grandfather's 8051s, either. I'm
trying to push the ARM-Mn as the microcontroller for the future. We
just switched to AVRs but there are a lot more choices in ARMs. If
the code is written properly, porting to a new processor isn't a big
deal.

Yes, but it's a re-layout and in many regulated environments you must go
through the whole big validation process again.

Not just layout but does anyone make a 12-clock, 12MHz 8051 anymore?


You can but there is no law against using a 25MHz or whatever version
with a 12MHz clock.

Well, then it's not a 12MHz clock. ;-) The greater issue is the
12-cycle (serial ALU). If you're insisting on a drop in, either will
screw all of your "agency approvals".

ARM *is* the way forward.


I might use my first one this year. Pondering which one to pick, one
that has good audio connectivity. Still got lots of time, maybe it'll be
the M4F series from TI. I was eyeing an AD Sharc but after a sobering
awakening with their seemingly outsourced "support" I decided not to.

We're in pretty deep with Atmel on their M0 and M4(ish) products.
Sharc is a DSP and isn't really much good as a controller. Very
expensive. We use a lot of them, in fact I'm using a 41279 and 41269
on a board I'm doing right now. For a cheaper DSP, the Sigma is
pretty good series (using one of them on another board that I've just
sorta wrapped up the schematic). Each board also has one of the Atmel
ARM Mn processors for the mundane stuff.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.

There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.
Use Automotive parts. They're committed to making them for at least a
decade. Of course that assumes you don't pick one that's already been
around two. ;-)

Or was specifically made for a car series that then gets discontinued in
two years. That is a problem with parts for consumer electronics sucha s
TV sets. I never use them anymore.

Name one (an ASSP, not an ASIC). Even if it's only in one car series,
it'll have at least a 10yr life, though if you only want one don't
count on any part being available in a decade.


I don't remember, too long ago. Mostly TAA, TBA and TCA series chips. I
haven't used them but clients have and then got burned.

More information?

... Does LTI give any assurance of a 20 year product life?
LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.
Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.
ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.

Oh yeah, some clients have been stung, big time. OTOH that has brought
me several "design-out" assignments that then turned into longterm
client relationships. One lasted all the way until the company owner died.

The company died with him? ...


Kind of. His widow ran it for another year or two. It is good not to
make any drastic asset changes right after a spouse passed away but
eventually she sold the company. It was a smart move on her part.

Probably a good idea but that still shouldn't kill the company.

... Of course the federal government wants
that to happen but it is still pretty poor planning.


You can't always avoid it. Sam's Town was a local Western style
entertainment city right in our village (Cameron Park). Mostly for kids
and many Bay Area folks fondly remember that from trips to Lake Tahoe,
when dad pointed his Studebaker towards the off ramp. Death taxes killed
it, along with over 150 well paying jobs. Those jobs never came back and
the place was bulldozed. Dems do not understand this stuff.

Death taxes have to be covered by insurance. But, that's what the
lefties in government want. They have to kill wealth. "It's only
fair."

 

[John Larkin]

On Sat, 31 May 2014 15:17:06 -0400, krw@attt.bizz wrote:

On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:

I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.


We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.

Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.


It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.

If you think that money (and time) invested has nothing to do with
"risk", perhaps. That's a rather Democratic view of economics,
though.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.

Crap! That must have been 1960. ;-)

If you need a 20 year production life, what parts *can* you use? ...


Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.

Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol


And I might. Plus opamps/comparators.


... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.


I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.

The 8051s of today aren't your grandfather's 8051s, either. I'm
trying to push the ARM-Mn as the microcontroller for the future. We
just switched to AVRs but there are a lot more choices in ARMs. If
the code is written properly, porting to a new processor isn't a big
deal.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.


There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.

Use Automotive parts. They're committed to making them for at least a
decade. Of course that assumes you don't pick one that's already been
around two. ;-)



... Does LTI give any assurance of a 20 year product life?


LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.

Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?


I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.

ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.

...

ADI just killed ADG465. It wasn't an especially old part... they just didn't
make enough money off it. Damned nuisance.


--

John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com

Precision electronic instrumentation

 

[Lasse Langwadt Christense]

Den søndag den 1. juni 2014 02.16.57 UTC+2 skrev Joerg:

Lasse Langwadt Christensen wrote:

Den l�rdag den 31. maj 2014 16.21.47 UTC+2 skrev Joerg:

rickman wrote:



On 5/30/2014 7:59 PM, Joerg wrote:

Stopband is a pretty gradual thing when you can't go past 3rd order on

the output filter. This application is sensitive to noise because the

load is super fast.

I guess I'm not really following all this. You have a control circuit

that is not easy to do with analog chips and yet you don't want to use a

digital control. From the bits and pieces I am seeing I believe a

classic ADC-DSP-DAC would suit this problem very well. ...









Generating a PWM stream with down to 1nsec granularity that way would be



increadibly power intense and expensive.





the dsPIC33 has ~1ns resolution PWM and a 10 bit 2Msps ADC, $1.69 if you buy 1000





How does it do that when the on-chip VCO for system frequency is spec'd

between 100MHz and 200MHz?

never used it so I don't know, look like you have to set it for 120Mhz to get 1.04ns resolution

Silicon delay wouldn't be so nice.

why not?

120MHz clock does the coarse duty cycle, a string 8 delays of nominal
1.04ns, servo the delays to make up exactly one cycle and you have 8
phases to do the fine setting duty cycle

I guess if the VCO is done with ring oscillator there is already a
string you can tap to get the extra phases for free

I believe Xilinx does something similar servoing of delays for their
IO delays

-Lasse

 

[Joerg]

krw@attt.bizz wrote:

On Sat, 31 May 2014 13:24:16 -0700, Joerg <invalid@invalid.invalid
wrote:

krw@attt.bizz wrote:
On Sat, 31 May 2014 12:36:07 -0700, Joerg <invalid@invalid.invalid
wrote:

krw@attt.bizz wrote:
On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:
rickman wrote:
I think you have the availability issue backwards. FPGA vendors have
some of the longest lived products in the IC world. It is not at all
uncommon to design in an FPGA when it is new and not get an EOL notice
for well over 10 years. You were dealing with Intel who dabble in
secondary business areas and then close up shop when they lose interest.
I don't know that Intel has ever shipped a production FPGA so I would
hardly call them an FPGA vendor in any sense of the word.

We also had it happen with a big medical system. Forgot which vendor but
all they could offer was to pour it into a new (more expensive) FPGA
series which would have meant a major relayout. So we poured it into our
own ASIC instead and that has no EOL issue.
Don't believe that for a moment! ASICs require a fab to be made. The
only FPGA I have ever had go EOL was because the fab house was closing
that fab line. FPGA makers don't build their own fabs like most chip
makers these days. ASICs are made on the same lines. When the fab
closes all the product either ends or goes to another fab which means
they have to work the process which is more NRE.

I'm curious about your story. Yes, FPGAs go EOL, but like I said not
remotely short lived. I would expect this design was either a long time
in production or they picked an FPGA that was already long in the tooth.

It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.
If you think that money (and time) invested has nothing to do with
"risk", perhaps. That's a rather Democratic view of economics,
though.

Huh? Going ASIC took a lot of risk out of this process. Instead of
depending on an FPGA manufacturer who is depending on a foundry we were
then only depending on a foundry.
You don't think significant NRE *ADDED* risk? You have a real funny
CFO.

Pouring it into an ASIC was not very onerous in terms of NRE. Plus we
could easily amortize it. It paid for itself in a jiffy anyhow because
the ASICs were much less expensive.

It had to have been a trivial part.

Absolutamente no. It does screaming fast image processing. No competitor
ever managed to rival it and they tried hard.

... ASICs are unaffordable for all
but a few applications. Really, they're only interesting when there
is no other choice (rather the same for FPGAs but on a whole different
level).

I have to disagree because I've been involved in a few ASIC projects. If
it's just pouring existing FPGA logic into an ASIC that can be done in
the high five digits. An ASIC from scratch is around half a million
after it's all said and done, depending on design complexity. Peanuts
compared to the savings or other upsides it provides.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.
Crap! That must have been 1960. ;-)

Yeah, I was surprised myself. But all the places we are using for the
various fab steps consider that standard fare.
Seriously, I thought everyone had gone to at least 6" wafers decades
back. It's been over a decade since the digital guys went to 12"
(300mm). Of course, 8" are still common for jelly beans.

That's what I thought as well. Until the end of last year. To me that
was like going to a car dealer and finding brand new 1956 Bel Airs.

OK, now it's clear that you're been working in Cuba. ;-)

Are they still making them?

If you need a 20 year production life, what parts *can* you use? ...
Tons. For example, I used CD4000 logic extensively. In the mid-90's a
Fairchild engineer told me that would be a stupid decision, they'd go
obsolete, I should use their single-package logic. Well, most of this is
still in production. Then staples such as the LM324, those are here to
stay. Also MMBT3904, BFS17, and so on. I just used a BFR92 on a new
design. The first time I used one I was in the mid-80's and even then it
wasn't exactly new.
Your example is CD4000 SSI/MSI logic? So why don't you build your
current design with those parts? lol
And I might. Plus opamps/comparators.


... I mean a part that is a bit more
complex. What MCUs have you used for 20 years other than the 8051? Many
MCU parts go obsolete in 10 years if not shorter. I've seen DSP chips
that lasted less than 5 years.

I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.
The 8051s of today aren't your grandfather's 8051s, either. I'm
trying to push the ARM-Mn as the microcontroller for the future. We
just switched to AVRs but there are a lot more choices in ARMs. If
the code is written properly, porting to a new processor isn't a big
deal.

Yes, but it's a re-layout and in many regulated environments you must go
through the whole big validation process again.
Not just layout but does anyone make a 12-clock, 12MHz 8051 anymore?

You can but there is no law against using a 25MHz or whatever version
with a 12MHz clock.

Well, then it's not a 12MHz clock. ;-) The greater issue is the
12-cycle (serial ALU). If you're insisting on a drop in, either will
screw all of your "agency approvals".

Not all of them. Software regression testing, yes. EMC approvals usually
not. But if you are plopping in a Testarossa-series modern MCU then you
get to do the whole enchilada, again.

ARM *is* the way forward.

I might use my first one this year. Pondering which one to pick, one
that has good audio connectivity. Still got lots of time, maybe it'll be
the M4F series from TI. I was eyeing an AD Sharc but after a sobering
awakening with their seemingly outsourced "support" I decided not to.

We're in pretty deep with Atmel on their M0 and M4(ish) products.
Sharc is a DSP and isn't really much good as a controller. Very
expensive. We use a lot of them, in fact I'm using a 41279 and 41269
on a board I'm doing right now. For a cheaper DSP, the Sigma is
pretty good series (using one of them on another board that I've just
sorta wrapped up the schematic). Each board also has one of the Atmel
ARM Mn processors for the mundane stuff.

I read a thread the other day that mentioned a vendor who had a list of
long life products they would commit to making for 10 years or so. I
can't remember where it was. The vendor may have been Motorola.

There is one other method but it requires you to be an important enough
customer: Negotiate a deal where, in case the product is ever obsoleted
in the first half of this century, you retain the right to have it made
at a foundry of your choice. For that, all the GDSII data goes into
escrow at some law office. It'll never come out of there if they stick
to their promise. But if they don't or if they go belly-up, it does.
Use Automotive parts. They're committed to making them for at least a
decade. Of course that assumes you don't pick one that's already been
around two. ;-)

Or was specifically made for a car series that then gets discontinued in
two years. That is a problem with parts for consumer electronics sucha s
TV sets. I never use them anymore.
Name one (an ASSP, not an ASIC). Even if it's only in one car series,
it'll have at least a 10yr life, though if you only want one don't
count on any part being available in a decade.

I don't remember, too long ago. Mostly TAA, TBA and TCA series chips. I
haven't used them but clients have and then got burned.

More information?

Those were projects back in Europe, last century. Most of that is gone.
One of the TCA-sumpthins was for electric drill speed control and I
believe then the drill series was discontinued. But really, it's too
long ago to say for sure. Lots of audio and RF/IF chips as well. They
suddenly became unobtanium.

... Does LTI give any assurance of a 20 year product life?
LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.
Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.
ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.

Oh yeah, some clients have been stung, big time. OTOH that has brought
me several "design-out" assignments that then turned into longterm
client relationships. One lasted all the way until the company owner died.
The company died with him? ...

Kind of. His widow ran it for another year or two. It is good not to
make any drastic asset changes right after a spouse passed away but
eventually she sold the company. It was a smart move on her part.

Probably a good idea but that still shouldn't kill the company.

Oh, it hasn't. But the new owners haven't used me (yet). AFAICT they
still produce my designs.

... Of course the federal government wants
that to happen but it is still pretty poor planning.

You can't always avoid it. Sam's Town was a local Western style
entertainment city right in our village (Cameron Park). Mostly for kids
and many Bay Area folks fondly remember that from trips to Lake Tahoe,
when dad pointed his Studebaker towards the off ramp. Death taxes killed
it, along with over 150 well paying jobs. Those jobs never came back and
the place was bulldozed. Dems do not understand this stuff.

Death taxes have to be covered by insurance.

What?

... But, that's what the
lefties in government want. They have to kill wealth. "It's only
fair."

Yep, and then they kill scores of jobs like here in California. Seems
they don't even do exit interviews which could reveal so much. Well,
maybe they want to hide how much damage they are doing.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

John Larkin wrote:

On Sat, 31 May 2014 15:17:06 -0400, krw@attt.bizz wrote:

On Sat, 31 May 2014 07:16:11 -0700, Joerg <invalid@invalid.invalid
wrote:

rickman wrote:
On 5/30/2014 8:10 PM, Joerg wrote:

[...]

LTC? Yes, pretty much. Before they call off anything they try to contact
anyone who has ever bought it to see if it's ok.
Yes, well everyone does that... although it is not a question really. So
if you tell LTI you are still using the part they will continue to make
it for you without quadrupling the price?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.
ADI hasn't stung us either. On the other end of the spectrum, I
wouldn't touch Maxim with Barak Obama's pole. Others do, and like
them. they do have some interesting parts but I *have* been bitten.

...


ADI just killed ADG465. It wasn't an especially old part... they just didn't
make enough money off it. Damned nuisance.

Arrow and Newark still have some. Farnell has stock in Europe and Asia
but often Newark stock seems to be physically the same as Farnell
Europe. Mouser has a few thousand as well. So at least there's
opportunity to stockpile.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

Lasse Langwadt Christensen wrote:

Den lřrdag den 31. maj 2014 16.21.47 UTC+2 skrev Joerg:
rickman wrote:

On 5/30/2014 7:59 PM, Joerg wrote:
Stopband is a pretty gradual thing when you can't go past 3rd order on
the output filter. This application is sensitive to noise because the
load is super fast.
I guess I'm not really following all this. You have a control circuit
that is not easy to do with analog chips and yet you don't want to use a
digital control. From the bits and pieces I am seeing I believe a
classic ADC-DSP-DAC would suit this problem very well. ...




Generating a PWM stream with down to 1nsec granularity that way would be

increadibly power intense and expensive.


the dsPIC33 has ~1ns resolution PWM and a 10 bit 2Msps ADC, $1.69 if you buy 1000

How does it do that when the on-chip VCO for system frequency is spec'd
between 100MHz and 200MHz?

Silicon delay wouldn't be so nice.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Chris Jones]

On 30/05/2014 07:20, Joerg wrote:

Folks,

Does anyone know an IC that can turn a control voltage into PWM and can
handle PWM frequencies in the 50-1000kHz range? Similar to a class D
driver but has to go down to DC. The changes in control would be
restricted to the audio spectrum below 15kHz.

The LTC6992 does this nicely but isn't precise enough. Same with
555-style timers or switcher chips. I am looking for better 1% and
ideally a lot better, including nonlinearity, drift, warts and all. A uC
is not suitable either because it should be simple and I need very fine
control granularity, down to around 0.1%.

Can't use short-lived consumer chips for radios and TV sets and such.

Maybe you don't strictly need PWM, but would be able to use sigma-delta
a modulated bitstream instead. In that case you could perhaps use this
one, though it comes with galvanic isolation that you might not need:
http://www.analog.com/static/imported-files/data_sheets/AD7401A.pdf
Perhaps there is something similar and cheaper without the isolation.

Otherwise if you really need PWM, what if you wrap feedback around the
LTC6992, i.e. invert and square up its output by putting the PWM through
a CMOS inverter running from a very stable power supply, and then use
resistors to add the inverted PWM waveform to the incoming input
voltage, and call the sum the "error voltage". Theoretically the average
of this "error voltage" will be exactly mid-rail. Use an op-amp to
integrate any deviations from mid-rail and feed that into the LTC6992,
to correct it. Perhaps two op-amps would be needed as integrating
circuits tend to invert, which you might not want here.

Chris

 

[josephkk]

On Sat, 31 May 2014 07:23:14 -0700, Joerg <invalid@invalid.invalid> wrote:

I am going to do something like that (but probably not with a 555) if
nothing single-chip comes up. That's the reason for this thread, to see
if there isn't anything out there. I mean, every class-D amp must have a
super-linear PWM generator. It's just that most have the power stages
built in (would be ok, can be left idle) and have lousy or no DC
performance (would not be ok).


Ok a weird question: Does the response need to be 0.1% for any step size
at 15 kHz? ...


Nope :-(


... Can it be "slew rate limited" a bit to get to 0.1% for a large
step; to like 900 Hz?


Unfortunately that would put a serious crimp into the versatility of the
product.

OK. Instead of a strict linearity perspective can we look at it from a
settling time perspective for various portions of step size from minimal
to full scale?

?-)

 

[josephkk]

On Sat, 31 May 2014 07:25:08 -0700, Joerg <invalid@invalid.invalid> wrote:

josephkk wrote:
On Thu, 29 May 2014 14:20:26 -0700, Joerg <invalid@invalid.invalid> wrote:

Folks,

Does anyone know an IC that can turn a control voltage into PWM and can
handle PWM frequencies in the 50-1000kHz range? Similar to a class D
driver but has to go down to DC. The changes in control would be
restricted to the audio spectrum below 15kHz.

The LTC6992 does this nicely but isn't precise enough. Same with
555-style timers or switcher chips. I am looking for better 1% and
ideally a lot better, including nonlinearity, drift, warts and all. A uC
is not suitable either because it should be simple and I need very fine
control granularity, down to around 0.1%.

Can't use short-lived consumer chips for radios and TV sets and such.

The only things that i have seen that are even close were V to F
converters. And they did DC to a few hundred Hz on the input spectrum.


Yup, I've used them but they aren't precise enough. Also, they don't
work well for PWM, just for V/F anf F/V.

Does it HAVE to be PWM? Can't PFM do the job?

Maybe some audiophool Class D amplifier IC.


T'is exactly what I am looking for and why I posted here

I had noticed.

 

[rickman]

On 5/31/2014 10:16 AM, Joerg wrote:

It was a cutting-edge FPGA in the mid 90's. With ASICs you can get much
more design security. The trick is to pick a foundry you trust and a
run-of-the-mills process that is used for tons of other products. By
going directly to the foundry you are cutting out one middleman (the
FPGA vendor) and thus reduce the overall risk.

I don't know what a "cutting edge" FPGA is other than a startup company.
Is that risky... yes of course.

You are speculating about the foundry vs. FPGA. All foundries are used
for "tons" of other products or they wouldn't stay in business. In
fact, the FPGA companies are the customers that define the foundry
business being the first real customers of the state of the art new fab
lines.

FPGAs are among the longest lived complex semiconductor devices out
there. You may find transitors, op amps and 8051s that live a lot
longer, but you won't find much LSI that lives longer than FPGAs.

An example for the longevity of semiconductor processes: We just started
something on a 4" wafer. Those date back almost to the days of
Methusaleh yet it's no problem. If a process is also used to make mil
stuff, chances are it'll survive both of us.

So? You can't find anything that competes with FPGAs in that technology.


> And I might. Plus opamps/comparators.

Ok, but you are here because you are finding this approach to be a PITA
because of all the accuracy issues.

I pretty much only used the 8051 when I was allowed to decide. Clients
have used Atmels and also PICs that have lasted a long time but I don't
have production data for those products.

Yes, some MCUs live for a while, but not 20 years. I have never seen an
MCU other (than the 8051 and a few Mil/aerospace processors) that long.
Why? Because no one wants them. They are old, slow and not cost
effective. If you seriously need a 20+ year production life without
redesign of any sort, then you will need to stick with 8051s and 4000
series CMOS. Is redesign really that big a problem that it can't be
done every 10 years or so?

I am pretty sure they will supply. They told me so and they've never
lied to me. Their prices are on the high side anyhow and I don't think
they would jack up the price on customers.

I have no idea what you base that on. If you ask them to make a part
they have discontinued it will cost an arm and a leg. Just give it a
thought for a bit. Running a fab is not cheap and making a run of parts
is not done for less than how many thousands of chips?

They _are_ making 100MHz 8051. No kidding. If it ain't got enough horses
use a 2nd one

And is that multiple sourced and long lived.. I doubt it. Even so, 100
MHz 8051 won't do this job without some analog support which takes you
back to your accuracy problems.

This is one reason why I try to keep things simple. Many jobs that are
done with a DSP can be done without. But not all of them, of course. Of
course, for me that's easier to say than probably for you because I do
mostly analog stuff. Sometimes it's the whole architecture though and
then one of my fuirst questions to the client is about parts sourcuiing
and longevity.

Who was it that said things should be done as simply as possible, but no
further. You are here because the analog approach is not so simple due
to the... well, analog effects.

--

Rick