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DDC11XEVM-PDK: 10M resistor on the input.

Salavat Magazov
Prodigy 20 points
Part Number: DDC11XEVM-PDK


The manual for the ADC does not specify any resistor to be placed between photodiode and input of the IC. But the PDK has such a resistor mounted. Presumably, I can bypass it with a jumper, however, before I do that I was wondering if you care to give a reason for the resistor presence in the PDK.

  • 0
    TI__Mastermind 19815 points

    Hi,

     Sorry for the delay.

     I am new to DDC family and was in a business travel/trip this week.

     I will try to get back to you within 48 hours.

    Thanks

  • 0
    TI__Expert 4680 points

    Hi Salavat,

    Will jump in... Yes, you are right. No resistor is needed in the final application. Connection of photodiode is done directly to the input of the DDC, as you expect.

    The reason for the resistor on the EVM is because customers may want to evaluate the linearity of the DDC. That is traditionally done by applying a known voltage at one extreme of the resistor which would then force a known current into the device. This assumes the input of the DDC is ground and the value of the resistor is known, but errors on those would translate on gain errors, not errors on the linearity measurement.

    The resistor is supplied so customer doesn't have to go looking for one but again, please bypass to connect to your photodiode.

    Best regards,
    Edu