Fast, efficient IR LEDs?

On Fri, 05 Feb 2010 11:43:30 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 5 Feb 2010 11:13:02 -0800 (PST), "miso_at_sushi.com"
miso_at_sushi.com> wrote:

[snip]

Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?

Ah, politics!

I wonder why lefties always assume that conservatives are stupid.
That's the "what's wrong with Kansas?" dilemma, the lament that the
working class won't toe the party line and follow the lead of their
betters.

Conservatives generally assume that lefties are both stupid and evil.

John

...lefties are both stupid and evil _and_ pathological liars.

Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (>  20 MHz,<  50 pF) for an optical feedback gizmo.
   I have some Stanley DN310s, but they've been discontinued.  Other
possibilities are:

Vishay    TSFF5410   -- 870 nm, 0.% W/A typ  15 ns rise/fall, 125 pF typ
Vishay    VSLB3940   -- 940 nm, 0.4 W/A typ  15 ns rise/fall,  70 pF typ
Panasonic LNA4905L   -- 880 nm, 0.3 W/A min  30 MHz typ, no other specs
Osram     SFH4550    -- 850 nm, 0.5 W/A typ  12 ns rise/fall,  no C spec

It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).

Any suggestions?

Thanks

Phil Hobbs

Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?

Nice try, Soup.  I enjoy talking electronics too much though.

His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

"Jim Thompson" <To-Email-Use-The-Envelope-Icon_at_My-Web-Site.com> schrieb im
Newsbeitrag news:uk6pm5dent8tsdv0642e3id6pqvor0f8d9_at_4ax.com...
On Fri, 05 Feb 2010 11:43:30 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 5 Feb 2010 11:13:02 -0800 (PST), "miso_at_sushi.com"
miso_at_sushi.com> wrote:

[snip]

Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?

Ah, politics!

I wonder why lefties always assume that conservatives are stupid.
That's the "what's wrong with Kansas?" dilemma, the lament that the
working class won't toe the party line and follow the lead of their
betters.

Conservatives generally assume that lefties are both stupid and evil.

John

...lefties are both stupid and evil _and_ pathological liars.


To me it seems both leftist and rightists are apparently mainly bored and
they appear boring to others as well. Nobody here is interested in political
drivel of any colour and it is a pity this group has turned into 90% crap.
ciao Ban

On Fri, 05 Feb 2010 11:56:15 -0500, Phil Hobbs
pcdhSpamMeSenseless_at_electrooptical.net> wrote:

I need a fast IR LED (> 20 MHz, < 50 pF) for an optical feedback gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:

Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec

It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).

Any suggestions?

Thanks

Phil Hobbs

PS: Amazing how we're actually talking about electronics at the moment!

Maybe use a visible part? They seem to get the most development effort
lately. I'll measure the capacitance on some of the right-angle
surface-mount Osram parts we use. They are blindingly bright, clearly
on at 1 uA in normal office lighting.

The red response of a silicon detector isn't much below the IR peak.

And now, back to politics...

John

Yes!! Bash them Russkies AKA REDs!

On Fri, 05 Feb 2010 09:25:28 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 05 Feb 2010 11:56:15 -0500, Phil Hobbs
pcdhSpamMeSenseless_at_electrooptical.net> wrote:

I need a fast IR LED (> 20 MHz, < 50 pF) for an optical feedback gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:

Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec

It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).

Any suggestions?

Thanks

Phil Hobbs

PS: Amazing how we're actually talking about electronics at the moment!
Maybe use a visible part? They seem to get the most development effort
lately. I'll measure the capacitance on some of the right-angle
surface-mount Osram parts we use. They are blindingly bright, clearly
on at 1 uA in normal office lighting.

The red response of a silicon detector isn't much below the IR peak.

And now, back to politics...

John


http://catalog.osram-os.com/catalogue/catalogue.do;jsessionid=6AC83F9F110FC71BC37646EE19F1BDDE?act=downloadFile&favOid=0200000200003436000100b6

I measured a red one of these at 9 pF, orange at 13.5. I have no idea
what the optical power output may be, or the ctr you can get into a
silicon detector. We consider 5 mA to be "bright" on the red and
green, 10 mA for the orange and blues. "Dim" is 1/10th that.

These are really nice led's. The colors are bright and pure, the
orange being especially nice looking. And they are dual-shot moulded,
so they don't melt when you solder them.

John


Hmmm...try the Rohm SMT LED, 755-SML-P12YTT86 is the Mouser P/N.

On Fri, 5 Feb 2010 11:13:02 -0800 (PST), "miso_at_sushi.com"
miso_at_sushi.com> wrote:

On Feb 5, 8:56 am, Phil Hobbs <pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (> 20 MHz, < 50 pF) for an optical feedback gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:

Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec

It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).

Any suggestions?

Thanks

Phil Hobbs

PS: Amazing how we're actually talking about electronics at the moment!

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot nethttp://electrooptical.net
Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?

Ah, politics!

I wonder why lefties always assume that conservatives are stupid.
That's the "what's wrong with Kansas?" dilemma, the lament that the
working class won't toe the party line and follow the lead of their
betters.

Conservatives generally assume that lefties are both stupid and evil.

John

It is not us poor "working" class no matter what "side", it is the

On Feb 5, 2:20 pm, Joerg <inva...@invalid.invalid> wrote:
Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (> 20 MHz,< 50 pF) for an optical feedback gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:
Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec
It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).
Any suggestions?
Thanks
Phil Hobbs
Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?
Nice try, Soup. I enjoy talking electronics too much though.
His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Sushi doesn't make for an evening meal. Just too light, even when
supplemented with miso soup. It's better for lunch.

Getting back to electronics., this is really an i=c*dv/dt issue. It
seems to me all you can do is reduce C if current is limited.
Unprogram it with C#...

On Sat, 6 Feb 2010 05:18:59 +0100, "Ban" <bansuri_at_web.de> wrote:

"Jim Thompson" <To-Email-Use-The-Envelope-Icon_at_My-Web-Site.com> schrieb im
Newsbeitrag news:uk6pm5dent8tsdv0642e3id6pqvor0f8d9_at_4ax.com...
On Fri, 05 Feb 2010 11:43:30 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 5 Feb 2010 11:13:02 -0800 (PST), "miso_at_sushi.com"
miso_at_sushi.com> wrote:

[snip]
Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?
Ah, politics!

I wonder why lefties always assume that conservatives are stupid.
That's the "what's wrong with Kansas?" dilemma, the lament that the
working class won't toe the party line and follow the lead of their
betters.

Conservatives generally assume that lefties are both stupid and evil.

John
...lefties are both stupid and evil _and_ pathological liars.

To me it seems both leftist and rightists are apparently mainly bored and
they appear boring to others as well. Nobody here is interested in political
drivel of any colour and it is a pity this group has turned into 90% crap.
ciao Ban


Design any cool electronics lately?

John

How about a 40V shunt regulator that varies less than 2V from 25C

m...@sushi.com wrote:
On Feb 5, 2:20 pm, Joerg <inva...@invalid.invalid> wrote:
Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (>  20 MHz,<  50 pF) for an optical feedback gizmo.
   I have some Stanley DN310s, but they've been discontinued.  Other
possibilities are:
Vishay    TSFF5410   -- 870 nm, 0.% W/A typ  15 ns rise/fall, 125 pF typ
Vishay    VSLB3940   -- 940 nm, 0.4 W/A typ  15 ns rise/fall,  70 pF typ
Panasonic LNA4905L   -- 880 nm, 0.3 W/A min  30 MHz typ, no other specs
Osram     SFH4550    -- 850 nm, 0.5 W/A typ  12 ns rise/fall,  no C spec
It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).
Any suggestions?
Thanks
Phil Hobbs
Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?
Nice try, Soup.  I enjoy talking electronics too much though.
His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Sushi doesn't make for an evening meal. Just too light, even when
supplemented with miso soup. It's better for lunch.

Getting back to electronics., this is really an i=c*dv/dt issue. It
seems to me all you can do is reduce C if current is limited.

   Unprogram it with C#...

John Larkin wrote:
On Sat, 6 Feb 2010 05:18:59 +0100, "Ban" <bansuri_at_web.de> wrote:

"Jim Thompson" <To-Email-Use-The-Envelope-Icon_at_My-Web-Site.com> schrieb im
Newsbeitrag news:uk6pm5dent8tsdv0642e3id6pqvor0f8d9_at_4ax.com...
On Fri, 05 Feb 2010 11:43:30 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:

On Fri, 5 Feb 2010 11:13:02 -0800 (PST), "miso_at_sushi.com"
miso_at_sushi.com> wrote:

[snip]
Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?
Ah, politics!

I wonder why lefties always assume that conservatives are stupid.
That's the "what's wrong with Kansas?" dilemma, the lament that the
working class won't toe the party line and follow the lead of their
betters.

Conservatives generally assume that lefties are both stupid and evil.

John
...lefties are both stupid and evil _and_ pathological liars.

To me it seems both leftist and rightists are apparently mainly bored and
they appear boring to others as well. Nobody here is interested in political
drivel of any colour and it is a pity this group has turned into 90% crap.
ciao Ban


Design any cool electronics lately?

John

How about a 40V shunt regulator that varies less than 2V from 25C
down to -70C (or less)?
Is that COOL or what?

On Feb 5, 2:20 pm, Joerg <inva...@invalid.invalid> wrote:
Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (> 20 MHz,< 50 pF) for an optical feedback gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:
Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec
It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).
Any suggestions?
Thanks
Phil Hobbs
Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?
Nice try, Soup. I enjoy talking electronics too much though.
His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Sushi doesn't make for an evening meal. Just too light, even when
supplemented with miso soup. It's better for lunch.

Getting back to electronics., this is really an i=c*dv/dt issue. It
seems to me all you can do is reduce C if current is limited.

miso_at_sushi.com wrote:
On Feb 5, 2:20 pm, Joerg <inva...@invalid.invalid> wrote:
Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (> 20 MHz,< 50 pF) for an optical feedback
gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:
Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec
It would be really nice to find something with a flat front facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).
Any suggestions?
Thanks
Phil Hobbs
Isn't low current and high speed mutually exclusive, like intelligence
and Republicans?
Nice try, Soup. I enjoy talking electronics too much though.
His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Sushi doesn't make for an evening meal. Just too light, even when
supplemented with miso soup. It's better for lunch.


4-5 rolls (servings) with 4 people and I am really stuffed afterwards.
But it's delicious.


Getting back to electronics., this is really an i=c*dv/dt issue. It
seems to me all you can do is reduce C if current is limited.


If Phil has to switch constantly, yes. Otherwise there could be a
"spiking circuit" that swings the C with gusto.

On 2/6/2010 12:41 PM, Joerg wrote:
miso_at_sushi.com wrote:
On Feb 5, 2:20 pm, Joerg <inva...@invalid.invalid> wrote:
Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (> 20 MHz,< 50 pF) for an optical feedback
gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:
Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec
It would be really nice to find something with a flat front facet
and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).
Any suggestions?
Thanks
Phil Hobbs
Isn't low current and high speed mutually exclusive, like
intelligence
and Republicans?
Nice try, Soup. I enjoy talking electronics too much though.
His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good
that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Sushi doesn't make for an evening meal. Just too light, even when
supplemented with miso soup. It's better for lunch.


4-5 rolls (servings) with 4 people and I am really stuffed afterwards.
But it's delicious.


Getting back to electronics., this is really an i=c*dv/dt issue. It
seems to me all you can do is reduce C if current is limited.


If Phil has to switch constantly, yes. Otherwise there could be a
"spiking circuit" that swings the C with gusto.


It's inside a feedback loop that needs to have >1 MHz bandwidth, so it's
more a loop stability vs bandwidth issue. There are alternatives, but
they're all more complicated than what we've got. I'd probably prefer
to trade off efficiency rather than speed and capacitance.

Phil Hobbs wrote:
On 2/6/2010 12:41 PM, Joerg wrote:
miso_at_sushi.com wrote:
On Feb 5, 2:20 pm, Joerg <inva...@invalid.invalid> wrote:
Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil
Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (> 20 MHz,< 50 pF) for an optical feedback
gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:
Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other
specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec
It would be really nice to find something with a flat front
facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).
Any suggestions?
Thanks
Phil Hobbs
Isn't low current and high speed mutually exclusive, like
intelligence
and Republicans?
Nice try, Soup. I enjoy talking electronics too much though.
His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good
that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Sushi doesn't make for an evening meal. Just too light, even when
supplemented with miso soup. It's better for lunch.


4-5 rolls (servings) with 4 people and I am really stuffed afterwards.
But it's delicious.


Getting back to electronics., this is really an i=c*dv/dt issue. It
seems to me all you can do is reduce C if current is limited.


If Phil has to switch constantly, yes. Otherwise there could be a
"spiking circuit" that swings the C with gusto.


It's inside a feedback loop that needs to have >1 MHz bandwidth, so
it's more a loop stability vs bandwidth issue. There are alternatives,
but they're all more complicated than what we've got. I'd probably
prefer to trade off efficiency rather than speed and capacitance.


Then you'll probably be in the market for the good stuff. This is an
example of one I've used in an optical feedback situation. I only needed
a little under 100MHz BW but it could have given me a lot more:

http://www.excelight.com/pdf/device/PD/SPT2400-x(revC).pdf

On 2/6/2010 3:13 PM, Joerg wrote:



Phil Hobbs wrote:
On 2/6/2010 12:41 PM, Joerg wrote:
m...@sushi.com wrote:
On Feb 5, 2:20 pm, Joerg <inva...@invalid.invalid> wrote:
Phil Hobbs wrote:
On 2/5/2010 2:13 PM, m...@sushi.com wrote:
On Feb 5, 8:56 am, Phil
Hobbs<pcdhSpamMeSensel...@electrooptical.net
wrote:
I need a fast IR LED (> 20 MHz,< 50 pF) for an optical feedback
gizmo.
I have some Stanley DN310s, but they've been discontinued. Other
possibilities are:
Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typ
Vishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typ
Panasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other
specs
Osram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C spec
It would be really nice to find something with a flat front
facet and
(especially) lower capacitance, because it has to work at quite low
currents (5-10 uA).
Any suggestions?
Thanks
Phil Hobbs
Isn't low current and high speed mutually exclusive, like
intelligence
and Republicans?
Nice try, Soup. I enjoy talking electronics too much though.
His "email address" always makes me crave miso soup and sushi. So, we
just went to the Japanese restaurant in town ...

But this time I had pork teriyaki after the miso soup. We usually have
sushi in the evenings, I can't really work after that, it's so good
that
I tend to eat too much of it.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Sushi doesn't make for an evening meal. Just too light, even when
supplemented with miso soup. It's better for lunch.

4-5 rolls (servings) with 4 people and I am really stuffed afterwards..
But it's delicious.

Getting back to electronics., this is really an i=c*dv/dt issue. It
seems to me all you can do is reduce C if current is limited.

If Phil has to switch constantly, yes. Otherwise there could be a
"spiking circuit" that swings the C with gusto.

It's inside a feedback loop that needs to have >1 MHz bandwidth, so
it's more a loop stability vs bandwidth issue. There are alternatives,
but they're all more complicated than what we've got. I'd probably
prefer to trade off efficiency rather than speed and capacitance.

Then you'll probably be in the market for the good stuff. This is an
example of one I've used in an optical feedback situation. I only needed
a little under 100MHz BW but it could have given me a lot more:

http://www.excelight.com/pdf/device/PD/SPT2400-x(revC).pdf

Hopefully not--that's megahertz, not gigahertz.  But I do want to be
able to work down at 500 nA or 1 uA.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot nethttp://electrooptical.net