So I've used the standard trans-impedance amplifier to sense the current of a photodiode. The photodiode is unbiased.
I went through the Spice simulations to calculate the stability and the value of the compensating capacitors I need and then I did the analog testing and then I made the pcb and it all works as designed.
However I encountered a possible failure mode that results in blowing the photodiode ( I did blow a test one) and I can't afford for that to happen ( there are 25 embeded photodidoes in a part that I can't replace easily and can't afford to).
I'm using a power supply (+-15V and ground) and if for whatever reason one of the power supply rails fails (simplest example is the +15 gets unplugged by mistake but originally I had a faulty power supply that resulted in this) the photodiode sees across it's terminals either + or - 15 V depending on which rail was unplugged (possibly 30 V ? if the ground cable is the disconnected ones?).
Either one of these ( 15V of forward or reverse bias) kills my photodiodes. As I said I have made my pcb so I don't have much space to implement some sort of current limiting. I considered fuses but I think they might be too slow or if I rate them low and the current peaks when the photodiode is illuminated by a particularly large source and it blows it would create the same failure mode as if I were to unplug one of the rails.
Anyone has any experience with this sort of problem ? The possible ideas I'd found so far are:
use a voltage regulators with a resistor to limit the current ( essentially becoming a current source) www.ti.com/lit/an/sbva011/sbva011.pdf
use some sort of current limiting circuit after the power supply. www.radio-electronics.com/info/circuits/transistor_current_limiter/transistor_current_limiter.php
Obviously I'd need two on both + and - side, but I'm not entirely sure how they would behave.
Any suggestions or advice is more than welcome.
P.s. links are not links since I don't have the rep to post links ...