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OPA857: OPA857 schematic review

Sammi Shang
Expert 4450 points
Part Number: OPA857

Dear team,

Would you kindly help review the schematic of OPA857?

Thanks.

Thanks.

Best regards,

Sammi

  • 0
    TI__Genius 15555 points

    Hello Sammi,

    I have two comments in regards to this schematic:

    1. Test_IN should be connected to VCC during normal operation.
    2. The reference voltage of your comparator should be adjusted... The output swing of the OPA857 is 1.83V (at 0A input) to 0.6V (at around 60uA assuming 20k-ohm gain). However looking at the specs of your photodiode, your short-circuit current is at 6uA which translates to 120mV or your output pin swinging to 1.71V. So in reality you will never reach your reference voltage at the current configuration.

    Best,

    Hasan Babiker