Fast, efficient IR LEDs?
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From: miso on 6 Feb 2010 01:58 On Feb 5, 9:55 pm, Robert Baer <robertb...(a)localnet.com> wrote: > m...(a)sushi.com wrote: > > On Feb 5, 2:20 pm, Joerg <inva...(a)invalid.invalid> wrote: > >> Phil Hobbs wrote: > >>> On 2/5/2010 2:13 PM, m...(a)sushi.com wrote: > >>>> On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...(a)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#... Windows? Yuck. I use gcc.
From: Joerg on 6 Feb 2010 12:41 miso(a)sushi.com wrote: > On Feb 5, 2:20 pm, Joerg <inva...(a)invalid.invalid> wrote: >> Phil Hobbs wrote: >>> On 2/5/2010 2:13 PM, m...(a)sushi.com wrote: >>>> On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...(a)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. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Phil Hobbs on 6 Feb 2010 13:44 On 2/6/2010 12:41 PM, Joerg wrote: > miso(a)sushi.com wrote: >> On Feb 5, 2:20 pm, Joerg <inva...(a)invalid.invalid> wrote: >>> Phil Hobbs wrote: >>>> On 2/5/2010 2:13 PM, m...(a)sushi.com wrote: >>>>> On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...(a)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. Thanks Phil -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Joerg on 6 Feb 2010 15:13 Phil Hobbs wrote: > On 2/6/2010 12:41 PM, Joerg wrote: >> miso(a)sushi.com wrote: >>> On Feb 5, 2:20 pm, Joerg <inva...(a)invalid.invalid> wrote: >>>> Phil Hobbs wrote: >>>>> On 2/5/2010 2:13 PM, m...(a)sushi.com wrote: >>>>>> On Feb 5, 8:56 am, Phil Hobbs<pcdhSpamMeSensel...(a)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 -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Phil Hobbs on 6 Feb 2010 15:51
On 2/6/2010 3:13 PM, Joerg wrote: > Phil Hobbs wrote: >> On 2/6/2010 12:41 PM, Joerg wrote: >>> miso(a)sushi.com wrote: >>>> On Feb 5, 2:20 pm, Joerg <inva...(a)invalid.invalid> wrote: >>>>> Phil Hobbs wrote: >>>>>> On 2/5/2010 2:13 PM, m...(a)sushi.com wrote: >>>>>>> On Feb 5, 8:56 am, Phil >>>>>>> Hobbs<pcdhSpamMeSensel...(a)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 net http://electrooptical.net |