EDAboard.com | EDAboard.eu | EDAboard.de | EDAboard.co.uk | RTV forum PL | NewsGroups PL

silly power supply

Ask a question - edaboard.com

elektroda.net NewsGroups Forum Index - Electronics Design - silly power supply

Goto page 1, 2, 3, 4, 5  Next

John Larkin
Guest

Wed Jan 11, 2017 8:30 am   



I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Various boost regs look like overkill to do this, to boost the
supplies a half volt or so. This dumb open-loop thing might work. I
can get the 5v p-p square wave off the +5 supply, chop it up with a
couple of mosfets.

This is another use for those cute Coilcraft dual-winding inductors. I
can get the schottky bridge as a single surface-mount part.

The negative side is the same idea, using the same 5v p-p source.


Version 4
SHEET 1 1924 740
WIRE 80 -688 -16 -688
WIRE 256 -688 144 -688
WIRE 384 -688 256 -688
WIRE 544 -688 448 -688
WIRE 256 -656 256 -688
WIRE -16 -560 -16 -688
WIRE 80 -560 -16 -560
WIRE 256 -560 256 -576
WIRE 256 -560 144 -560
WIRE 384 -560 256 -560
WIRE 544 -560 544 -688
WIRE 544 -560 448 -560
WIRE 784 -560 544 -560
WIRE 880 -560 784 -560
WIRE 960 -560 880 -560
WIRE 544 -528 544 -560
WIRE -16 -496 -16 -560
WIRE 784 -496 784 -560
WIRE -16 -368 -16 -416
WIRE 544 -368 544 -464
WIRE 784 -368 784 -416
WIRE 192 -192 -16 -192
WIRE 368 -192 256 -192
WIRE 544 -192 448 -192
WIRE -16 -144 -16 -192
WIRE 544 -128 544 -192
WIRE -16 -16 -16 -64
FLAG 784 -368 0
FLAG 880 -560 POS
FLAG -16 -368 0
FLAG -16 -16 0
FLAG 544 -128 0
FLAG 544 -368 0
SYMBOL ind2 352 -176 R270
WINDOW 0 -47 57 VTop 2
WINDOW 3 -57 56 VBottom 2
SYMATTR InstName L1
SYMATTR Value 33
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.33
SYMBOL schottky 384 -544 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value RSX205L-30
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 528 -528 R0
WINDOW 0 65 34 Left 2
WINDOW 3 61 72 Left 2
SYMATTR InstName C2
SYMATTR Value 56
SYMBOL current 784 -496 R0
WINDOW 0 78 6 Left 2
WINDOW 3 -168 174 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName I1
SYMATTR Value PULSE(64m 800m 5m 0 0 5m)
SYMBOL ind2 240 -560 M180
WINDOW 0 -44 75 Left 2
WINDOW 3 -50 40 Left 2
SYMATTR InstName L2
SYMATTR Value 33
SYMATTR Type ind
SYMATTR SpiceLine Rser=0.33
SYMBOL voltage -16 -512 R0
WINDOW 0 57 77 Left 2
WINDOW 3 56 115 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value 11.5
SYMBOL voltage -16 -160 R0
WINDOW 0 84 74 Left 2
WINDOW 3 50 129 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value PULSE(0 5 0 50n 50n 950n 2u)
SYMBOL schottky 384 -672 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D2
SYMATTR Value RSX205L-30
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 80 -544 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D3
SYMATTR Value RSX205L-30
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 80 -672 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D4
SYMATTR Value RSX205L-30
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 256 -208 R90
WINDOW 0 -14 31 VBottom 2
WINDOW 3 46 29 VTop 2
SYMATTR InstName C1
SYMATTR Value 56
TEXT 824 -64 Left 2 !.tran 15m
TEXT 760 -160 Left 2 ;V377 Pos Rail Booster
TEXT 792 -112 Left 2 ;JL Jan 10, 2017
TEXT 208 -384 Left 2 !K1 L1 L2 0.995
TEXT 48 -224 Left 2 ;5V p-p
TEXT 840 -448 Left 2 ;LOAD
TEXT 240 -344 Left 2 ;DRQ127


I guess I could also buy some standard 12-to-3.3 volt dc/dc converters
and stack the 3.3's on top of the 12's.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

rickman
Guest

Wed Jan 11, 2017 8:30 am   



On 1/11/2017 12:51 AM, John Larkin wrote:
Quote:


I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe.


What's a VME supply?

--

Rick C

tom
Guest

Wed Jan 11, 2017 8:30 am   



"John Larkin" <jjlarkin_at_highlandtechnology.com> wrote in message
news:eqgb7ctpiljn6k48ej99ghmdbfo6hlc3m6_at_4ax.com...
Quote:


I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Various boost regs look like overkill to do this, to boost the
supplies a half volt or so. This dumb open-loop thing might work. I
can get the 5v p-p square wave off the +5 supply, chop it up with a
couple of mosfets.

This is another use for those cute Coilcraft dual-winding inductors. I
can get the schottky bridge as a single surface-mount part.

The negative side is the same idea, using the same 5v p-p source.



There are a ton of really cheap boost converters out of the far east on
ebay. Cheaper than the parts shipping cost if you try to build it in house.


http://www.ebay.com/itm/DC-DC-Boost-adjustable-step-up-Converter-XL6009-Module-Voltage-New-US-ship-/132057534060?hash=item1ebf3e0e6c:g:uKMAAOSw2GlXDZUs

If they fail to work, you get your money back.

Have fun.

Adrian Caspersz
Guest

Wed Jan 11, 2017 5:52 pm   



On 11/01/17 07:17, rickman wrote:
Quote:
On 1/11/2017 12:51 AM, John Larkin wrote:


I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe.

What's a VME supply?


For https://en.wikipedia.org/wiki/VMEbus ?

--
Adrian C

rickman
Guest

Wed Jan 11, 2017 6:05 pm   



On 1/11/2017 5:52 AM, Adrian Caspersz wrote:
Quote:
On 11/01/17 07:17, rickman wrote:
On 1/11/2017 12:51 AM, John Larkin wrote:


I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe.

What's a VME supply?


For https://en.wikipedia.org/wiki/VMEbus ?


A freaking 30 year old bus??? My first thought was why didn't he just
get a supply that would provide the current needed without the half volt
of droop? I suppose he is retrofitting some antique gear.

--

Rick C

Winfield Hill
Guest

Wed Jan 11, 2017 7:17 pm   



John Larkin wrote...
Quote:

I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Various boost regs look like overkill to do this, to boost the
supplies a half volt or so. This dumb open-loop thing might work. I
can get the 5v p-p square wave off the +5 supply, chop it up with a
couple of mosfets.

This is another use for those cute Coilcraft dual-winding inductors. I
can get the schottky bridge as a single surface-mount part.

The negative side is the same idea, using the same 5v p-p source.


Here's my solution to this common problem. It relies on
coupled inductors with their normal very tight coupling.
I originallly needed to convert common 12V silicon MOSFET
driver levels to +16 and -4V, to drive SiC MOSFETs. I
had very little space available and wanted a simple fix.
I used an LT3467 in a sot-23 package and a small srf0703
coupled inductor (it's running at 1.3MHz). Use a larger
low-value inductor if you need more power. A simple re-
arrangement makes this work for +/- 15V supplies from 12V.

https://www.dropbox.com/s/wxazk2hu7ph3k1x/supplies_SiC_%C2%B115V.pdf?dl=0


--
Thanks,
- Win

George Herold
Guest

Wed Jan 11, 2017 7:22 pm   



On Wednesday, January 11, 2017 at 12:51:20 AM UTC-5, John Larkin wrote:
Quote:
I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Various boost regs look like overkill to do this, to boost the
supplies a half volt or so. This dumb open-loop thing might work. I
can get the 5v p-p square wave off the +5 supply, chop it up with a
couple of mosfets.

This is another use for those cute Coilcraft dual-winding inductors. I
can get the schottky bridge as a single surface-mount part.

The negative side is the same idea, using the same 5v p-p source.



I guess I could also buy some standard 12-to-3.3 volt dc/dc converters
and stack the 3.3's on top of the 12's.

How does that help if you are running out of power on the 12V rail...
(or is it only the drooping to 11.5 that is hurting you?)
Maybe DC-DC converter from the 5V rail? (So far I'm liking the
CUI three terminal 500mA DC-DC converters. they make 1.8 V ones
$5 no muss, no fuss)

George H.

Or tweak the specs 9Vp-p into 100 ohm, or 10 Vp-p into 150 ohms.
Quote:


--

John Larkin Highland Technology, Inc

lunatic fringe electronics


George Herold
Guest

Wed Jan 11, 2017 8:22 pm   



On Wednesday, January 11, 2017 at 12:58:34 PM UTC-5, John Larkin wrote:
Quote:
On Wed, 11 Jan 2017 09:22:53 -0800 (PST), George Herold
gherold_at_teachspin.com> wrote:

On Wednesday, January 11, 2017 at 12:51:20 AM UTC-5, John Larkin wrote:
I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Various boost regs look like overkill to do this, to boost the
supplies a half volt or so. This dumb open-loop thing might work. I
can get the 5v p-p square wave off the +5 supply, chop it up with a
couple of mosfets.

This is another use for those cute Coilcraft dual-winding inductors. I
can get the schottky bridge as a single surface-mount part.

The negative side is the same idea, using the same 5v p-p source.



I guess I could also buy some standard 12-to-3.3 volt dc/dc converters
and stack the 3.3's on top of the 12's.
How does that help if you are running out of power on the 12V rail...
(or is it only the drooping to 11.5 that is hurting you?)

There are plenty of amps available, but not quite enough voltage for
the power opamps to reliably swing +-10 into the loads.


Maybe DC-DC converter from the 5V rail? (So far I'm liking the
CUI three terminal 500mA DC-DC converters. they make 1.8 V ones
$5 no muss, no fuss)


One idea is to get a couple of isolated dc/dc converters, 5 or 12 or
24 volts input, a couple of volts out, and stack their outputs in
series with the existing +12 and -12 rails. But I need about 1 amp,
and the only converter choices are expensive and sole-sourced.

Hmm I see more than one on DK.
Some by Recom power. And then these
http://www.xppower.com/Portals/0/pdfs/SF_SR.pdf
(but not a lot of stock at DK, which always worries me.)
Oh Cui has some too...
http://www.cui.com/product/resource/p78a-1000.pdf

That should do it!

George H.

Quote:

What I need is a 1-volt output, 1 or 2 watt isolated dc/dc.

CUI does make good stuff.



George H.

Or tweak the specs 9Vp-p into 100 ohm, or 10 Vp-p into 150 ohms.

Too late! I need to be compatible with the old product, +-10 behind 50
ohms. It used four paralleled RRO opamps per channel, but they were
slow, and some customers want higher speed outputs. THS6022 is ideal,
screaming fast and tons of current, and we have them, but they are not
RRO.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics


John Larkin
Guest

Wed Jan 11, 2017 11:47 pm   



On 11 Jan 2017 04:17:05 -0800, Winfield Hill
<hill_at_rowland.harvard.edu> wrote:

Quote:
John Larkin wrote...

I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Various boost regs look like overkill to do this, to boost the
supplies a half volt or so. This dumb open-loop thing might work. I
can get the 5v p-p square wave off the +5 supply, chop it up with a
couple of mosfets.

This is another use for those cute Coilcraft dual-winding inductors. I
can get the schottky bridge as a single surface-mount part.

The negative side is the same idea, using the same 5v p-p source.

Here's my solution to this common problem. It relies on
coupled inductors with their normal very tight coupling.
I originallly needed to convert common 12V silicon MOSFET
driver levels to +16 and -4V, to drive SiC MOSFETs. I
had very little space available and wanted a simple fix.
I used an LT3467 in a sot-23 package and a small srf0703
coupled inductor (it's running at 1.3MHz). Use a larger
low-value inductor if you need more power. A simple re-
arrangement makes this work for +/- 15V supplies from 12V.

https://www.dropbox.com/s/wxazk2hu7ph3k1x/supplies_SiC_%C2%B115V.pdf?dl=0


I tried a few similar circuits,

https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Dual_Boost_1.jpg

using parts that we have in stock, but they are relatively complex and
the transient response of the non-regulated side is sloppy. My load
can jump from around 60 mA (opamp idle current) to close to 1 amp.
That argues for the + and - supplies to be independent.

The open-loop thing is sure simple, but I'm still open to suggestions.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics

John Larkin
Guest

Thu Jan 12, 2017 12:09 am   



On Wed, 11 Jan 2017 10:52:13 +0000, Adrian Caspersz
<email_at_here.invalid> wrote:

Quote:
On 11/01/17 07:17, rickman wrote:
On 1/11/2017 12:51 AM, John Larkin wrote:


I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe.

What's a VME supply?


For https://en.wikipedia.org/wiki/VMEbus ?


Yes, I'm redesigning an old (originally 1993) VME module. My old
design had 7 FPGAs and a 68K CPU, and a mountain of analog stuff. The
new one will use one big FPGA and a ARM chip and do most of the
processing (DDS, summing, filtering, modulations) digitally.

This is the old one:

http://www.highlandtechnology.com/DSS/V375DS.shtml

The new board will be practically empty. The FPGA, CPU, four DACs,
output amps, a bit of power supply. I'd use a ZYNQ SOC, but they don't
have much on-chip SRAM for some reason. The power supply is a little
interesting; the rest is mainly grunt work.

The history of VME is interesting; some other time.



--

John Larkin Highland Technology, Inc

lunatic fringe electronics

John Larkin
Guest

Thu Jan 12, 2017 12:58 am   



On Wed, 11 Jan 2017 09:22:53 -0800 (PST), George Herold
<gherold_at_teachspin.com> wrote:

Quote:
On Wednesday, January 11, 2017 at 12:51:20 AM UTC-5, John Larkin wrote:
I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Various boost regs look like overkill to do this, to boost the
supplies a half volt or so. This dumb open-loop thing might work. I
can get the 5v p-p square wave off the +5 supply, chop it up with a
couple of mosfets.

This is another use for those cute Coilcraft dual-winding inductors. I
can get the schottky bridge as a single surface-mount part.

The negative side is the same idea, using the same 5v p-p source.



I guess I could also buy some standard 12-to-3.3 volt dc/dc converters
and stack the 3.3's on top of the 12's.
How does that help if you are running out of power on the 12V rail...
(or is it only the drooping to 11.5 that is hurting you?)


There are plenty of amps available, but not quite enough voltage for
the power opamps to reliably swing +-10 into the loads.


Quote:
Maybe DC-DC converter from the 5V rail? (So far I'm liking the
CUI three terminal 500mA DC-DC converters. they make 1.8 V ones
$5 no muss, no fuss)


One idea is to get a couple of isolated dc/dc converters, 5 or 12 or
24 volts input, a couple of volts out, and stack their outputs in
series with the existing +12 and -12 rails. But I need about 1 amp,
and the only converter choices are expensive and sole-sourced.

What I need is a 1-volt output, 1 or 2 watt isolated dc/dc.

CUI does make good stuff.


Quote:

George H.

Or tweak the specs 9Vp-p into 100 ohm, or 10 Vp-p into 150 ohms.


Too late! I need to be compatible with the old product, +-10 behind 50
ohms. It used four paralleled RRO opamps per channel, but they were
slow, and some customers want higher speed outputs. THS6022 is ideal,
screaming fast and tons of current, and we have them, but they are not
RRO.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

Winfield Hill
Guest

Thu Jan 12, 2017 1:21 am   



John Larkin wrote...
Quote:

the transient response of the non-regulated side is sloppy. My load
can jump from around 60 mA (opamp idle current) to close to 1 amp.
That argues for the + and - supplies to be independent.

The open-loop thing is sure simple, but I'm still open to suggestions.


I have taken measurements on real circuits that show
amazing regulation of the non-regulated side. It's
a matter of the quality of your coupled inductors.
Also, assuming you have +/-12V, keep in mind you're
only making a pair of 2-volt supplies.


--
Thanks,
- Win

Winfield Hill
Guest

Thu Jan 12, 2017 1:55 am   



John Larkin wrote...
Quote:


Your output capacitors are too small.


--
Thanks,
- Win

John Larkin
Guest

Thu Jan 12, 2017 2:43 am   



On 11 Jan 2017 10:55:42 -0800, Winfield Hill
<hill_at_rowland.harvard.edu> wrote:

Quote:
John Larkin wrote...

https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/Dual_Boost_1.jpg

Your output capacitors are too small.


The -12 supply can actually be -11.6, maybe even a bit lower with
connector and trace losses, so margin is even worse than it looks. I
already have 330uF.


--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Jon Elson
Guest

Thu Jan 12, 2017 3:14 am   



John Larkin wrote:

Quote:


I'm doing an arbitrary waveform generator that uses a bunch of THS6022
monster opamps for the outputs. I have +-12 volt VME supples that
could droop as low as 11.5 maybe. I need +-10 volts of output swing
into 100 ohms, and the supplies are literally a couple of tenths of a
volt away from working. How annoying.

Why not just change a resistor in the power supply to get a half volt more
out of it? They might even have an adjuting pot with that much range.

Jon

Goto page 1, 2, 3, 4, 5  Next

elektroda.net NewsGroups Forum Index - Electronics Design - silly power supply

Ask a question - edaboard.com

Arabic versionBulgarian versionCatalan versionCzech versionDanish versionGerman versionGreek versionEnglish versionSpanish versionFinnish versionFrench versionHindi versionCroatian versionIndonesian versionItalian versionHebrew versionJapanese versionKorean versionLithuanian versionLatvian versionDutch versionNorwegian versionPolish versionPortuguese versionRomanian versionRussian versionSlovak versionSlovenian versionSerbian versionSwedish versionTagalog versionUkrainian versionVietnamese versionChinese version
RTV map EDAboard.com map News map EDAboard.eu map EDAboard.de map EDAboard.co.uk map