PXIe-4303 for Reading Photodiodes?

[Gregory]

For my setup, I need to read the current from 32 photodiodes at 50kS/s, so it almost seemed too perfect when I came across the PXIe-4303 card:

"24-Bit, 32-Channel, 51.2 kS/s, ±10 V PXI Analog Input Module - The PXIe‑4303 is a filtered input module for voltage, thermocouple, and current measurements."

I would also plan to purchase the TB-4302C,Current input front mount terminal block for PXIe-4302/3. My typical readings are from 10-400uA, and the photodiodes need to be reverse biased at 5V.

After looking at the manual, I'm still confused about that part, could this card take care of the reverse bias?

Thank you,

Gregory

[t@nim@t0R · Accepted solution]

gregoryj, 

Unfortunately, the 4303 Analog Input module will not be able to provide the reverse-bias to your photodiode. Can you explain to me how you have achieved this reverse bias in the past, if you have done so before?

[Gregory]

Hi t@nim@t0R,

Right now we use a very simple circuit, like the one below. We just measure the voltage over the resistor, and the resistor can be switched between 100k or 1k Ohms.

[t@nim@t0R]

Ah, I see. Yes the 4303 is only an input module, and thus will not be able to source the 5V. I would look at some of our Analog Output modules if you need a 5V supply. 

[Gregory]

Thank you, it may work fine without the reverse bias, but I'll have to do some testing to find out!

[Henrik_Volkers]

With about 2.88V to ~3.3V Bias, you can use the PFI output as a voltage source.... (with 5mA max). Alternatin that pin and with the help of some diodes and caps you can get a 5V bias...  but with ripple and most probably additional noise on your inputs.

So an external  (clean, battery?)  supply would be needed.

Looking at the spec and manual of the 4303 I wonder about the connector: The PFI is referenced against the DGND , but which pin in the manual table 2-1 is DGND???

[t@nim@t0R]

Henrik_Volkers,

DGND is row 2 column B (as indicated per pg. 2-7 of the following manual http://www.ni.com/pdf/manuals/377003a.pdf)

[Henrik_Volkers]

found it 🙂