Forward baised photodiode
in [Design]
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From: George Herold on 9 Jul 2010 13:26 Right, who would do such a stupid thing? This is for a piece of equipment that will be used by students. They get to hook up the photodiode and it's guaranteed that 1/2 of them will do it backwards the first time. (And the other half will do it backwards the second time.) The power supply that biases the PD is current limited at about 250mA. With this much current the forward drop across the PD (PIN-3CD from OSI) is 1.35 Volts at room temp. (0.34 Watts.) Ive been cooking the PD on my bench for several hours. Its a bit warm, forward voltage drop is now 1.29 V. (Its nice that it goes down.) From which I guesstimate the temperature rise to be about 30 C. (60 mV) Is this going to damage the photodiode in any way? Seems like it should be fine. Thanks George H.
From: Joerg on 9 Jul 2010 13:40 George Herold wrote: > Right, who would do such a stupid thing? > > This is for a piece of equipment that will be used by students. They > get to hook up the photodiode and it's guaranteed that 1/2 of them > will do it backwards the first time. (And the other half will do it > backwards the second time.) The power supply that biases the PD is > current limited at about 250mA. ... 250mA? Yikes! Why? > ... With this much current the forward > drop across the PD (PIN-3CD from OSI) is 1.35 Volts at room temp. > (0.34 Watts.) > I�ve been cooking the PD on my bench for several hours. It�s a bit > warm, forward voltage drop is now 1.29 V. (It�s nice that it goes > down.) From which I guesstimate the temperature rise to be about 30 > C. (60 mV) > > Is this going to damage the photodiode in any way? Seems like it > should be fine. > It's certainly not a healthy modus operandi. What does the datasheet say under abs max? -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: GregS on 9 Jul 2010 13:47 In article <b10c87fb-0221-44e4-98f5-b7ced8046c28(a)d37g2000yqm.googlegroups.com>, George Herold <gherold(a)teachspin.com> wrote: >Right, who would do such a stupid thing? > >This is for a piece of equipment that will be used by students. They >get to hook up the photodiode and it's guaranteed that 1/2 of them >will do it backwards the first time. (And the other half will do it >backwards the second time.) The power supply that biases the PD is >current limited at about 250mA. With this much current the forward >drop across the PD (PIN-3CD from OSI) is 1.35 Volts at room temp. >(0.34 Watts.) >I=92ve been cooking the PD on my bench for several hours. It=92s a bit >warm, forward voltage drop is now 1.29 V. (It=92s nice that it goes >down.) From which I guesstimate the temperature rise to be about 30 >C. (60 mV) > >Is this going to damage the photodiode in any way? Seems like it >should be fine. > Once, I hooked up the Tripplet 630 to check out a large diode and it blew. I could see the wire that fused. Was expensive too. I just measured that meter to a ma. meter and was about 200 ma at RX1. greg
From: Phil Hobbs on 9 Jul 2010 14:10 George Herold wrote: > Right, who would do such a stupid thing? > > This is for a piece of equipment that will be used by students. They > get to hook up the photodiode and it's guaranteed that 1/2 of them > will do it backwards the first time. (And the other half will do it > backwards the second time.) The power supply that biases the PD is > current limited at about 250mA. With this much current the forward > drop across the PD (PIN-3CD from OSI) is 1.35 Volts at room temp. > (0.34 Watts.) > I�ve been cooking the PD on my bench for several hours. It�s a bit > warm, forward voltage drop is now 1.29 V. (It�s nice that it goes > down.) From which I guesstimate the temperature rise to be about 30 > C. (60 mV) > > Is this going to damage the photodiode in any way? Seems like it > should be fine. > > Thanks > > George H. Depends on the PD. Some have really thin epi for good blue response, which leads to a lot of current crowding near the contact, so that they die with an applied forward bias but easily survive the same size photocurrent. If it doesn't die right away, and the leakage doesn't get degraded by the experience, you should be fine. 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
From: George Herold on 9 Jul 2010 14:35
On Jul 9, 1:40 pm, Joerg <inva...(a)invalid.invalid> wrote: > George Herold wrote: > > Right, who would do such a stupid thing? > > > This is for a piece of equipment that will be used by students. They > > get to hook up the photodiode and it's guaranteed that 1/2 of them > > will do it backwards the first time. (And the other half will do it > > backwards the second time.) The power supply that biases the PD is > > current limited at about 250mA. ... > > 250mA? Yikes! Why? Why 250 mA? Well the power supply can used for other things also. The biggest power hog is running a light bulb. > > > ... With this much current the forward > > drop across the PD (PIN-3CD from OSI) is 1.35 Volts at room temp. > > (0.34 Watts.) > > Ive been cooking the PD on my bench for several hours. Its a bit > > warm, forward voltage drop is now 1.29 V. (Its nice that it goes > > down.) From which I guesstimate the temperature rise to be about 30 > > C. (60 mV) > > > Is this going to damage the photodiode in any way? Seems like it > > should be fine. > > It's certainly not a healthy modus operandi. What does the datasheet say > under abs max? Data sheet says nothing... Some list a maxiumum short circuit photo current but that's sure to be much less than 250 mA. At full light I can only get about 10mA from the diode. George H. (Hmm I guess I could ask the manufacturer) > > -- > Regards, Joerg > > http://www.analogconsultants.com/ > > "gmail" domain blocked because of excessive spam. > Use another domain or send PM. |