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Dears
I want to choose a 24bit, I/V conversion pre-op amplifier for the silicon photovoltaic cell, the photocurrent is 40pA~500nA, and the low input offset current LMP7721MAX/NOPB. I want to ask if it is appropriate?
Is ADS1246 suitable for optical signal acquisition?
Thanks
Elsa Duan
Elsa,
If you use 5V supply, LMP7721 is the right part with the lowest IB but because of its 17MHz GBW uses 1.3mA quiescent current. If your supply is above 5.5V but below 16V, you may use LMC6482. Also, if you don't need the speed and operate close to room temperature, you should also consider using LMP2231 with IQ of just 10uA - see below.
As far as your question about ADS1246 suitability is concerned, it seems to me appropriate choice considering it is meant for precision sensor measurement. But to be sure, it would be good to confirm this selection with delta-sigma product line.
The bandwidth required most likely is not high considering it measure photovoltaic current and may be adjusted based on Cj to stabilize the circuit - see below.
