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Input offset tempcos for ADCMP600 series comparators?

Hi all,

I'm working on a new design that currently uses an ADCMP607 to convert user-input sine waves to square waves for timing input.  There are lots of signal-conditioning front-end bits ahead of the comparator, ending with the ADCMP607.  Despite having +30dB analog gain in front of the ADCMP607 (including some careful limiting using the AD8037 clamp amp), it seems clear that the comparator is dominating the tempco of the overall circuit.  Spraying cold onto the components one-by-one, starting with the JFET input opamp, showed little effect until I hit the ADCMP.

Some other ADCMP comparators (such as ADCMP551 and ADCMP572) are specified with tempco's, any of which would be good enough for my application.  However, none of those are as good a match otherwise to my application (which needs the programmable hysteresis pin, only needs a single comparator, and ideally keeps the CML outputs).

Is there any data on what to expect for tempco's from the ADCMP607?

Thanks in advance,

--Matt

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  • Matt,

      If I take the +/-5mV Vos over 165 deg C range, I get 60 uV/deg C.  So I would take that as a probable max.

    What is your min/max signal frequency??  If the input slew rate is large enough, and you have xx millivolts

    of hysteresis, it seems that TCVos would not be a problem?  What is the value of Rhyst??

    In addition to Vos, you also have to consider Ibias and Ios.  What are the two source impedances

    for the comparator?  What is the max TC of the resistors?

    Maybe someone from the product line will jump in with a more realistic number for  TCVos.

    Harry

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  • Matt,

      If I take the +/-5mV Vos over 165 deg C range, I get 60 uV/deg C.  So I would take that as a probable max.

    What is your min/max signal frequency??  If the input slew rate is large enough, and you have xx millivolts

    of hysteresis, it seems that TCVos would not be a problem?  What is the value of Rhyst??

    In addition to Vos, you also have to consider Ibias and Ios.  What are the two source impedances

    for the comparator?  What is the max TC of the resistors?

    Maybe someone from the product line will jump in with a more realistic number for  TCVos.

    Harry

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