Setting Voltage reference for a Comparator

[MouradR]

Hi There,


I have a Voltage comparator ADCMP600 and I am trying to set the threshold (reference) voltage to 20mV and this can be achieved by connecting 20mV to pin 4 (Inverting analog input).

My question is how to get 20mV from 3V voltage supply. I know the obvious solution is voltage divider but I feel because the ratio between resistors is too high (e.g 1k,6.8 ohm) it won't

be stable or work properly. Is there any guarantee way to generate this low threshold voltage.

NOTE: I don't have micro controller on the board

Cheers,
-MR

 

[FvM]

Can you imagine a reason why the 150:1 ratio should be a problem for a voltage divider? I can't. A voltage divider is just the usual way to do it.

 

[dick_freebird]

A close-in voltage divider, referred tightly to the input-signal-
of-interest reference ground, is the best option I've ever seen.
At 20mV you will be challenged to test in any but the most ideal
lab bench conditions, or have to play teicks like putting the
assembly inside an integrator loop looking for Vdd/2 output
and filtering out the chatter.

The only thing you have to fear in setting up a large ratio
divider, is any unanticipated shunt conductances about the
high valued resistors. That's basically board fab & handling
hygeine, conformal coating and moisture purge (for low temp)
etc. along with keeping the shunt value of the divider well
below Zin(comparator).