LMC6772-Q1: Power on issue

Hello Songzhen,

Without seeing all the inputs, it is hard to tell what is causing the output to trigger, especially when the outputs are tied together. It looks like the comparator is starting to awaken about 2V, which is below the minimum supply of 2.7V.

They may wish to take a look at the LM393LV-Q1, which has a POR circuit that keeps the output high-z (High) until it crosses the minimum supply plus a 50us delay.

Hi Songzhen,

another remedy is to add a discrete transistor stage which needs a minimum supply voltage of 3.5V to be able to skip, as discussed here:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1074090/lm2903b-output-status-under-vcc-2v-during-power-up

This can mean that you need to reverse the polarity of inputs of comparator.

Kai

Hello Songzhen,

I think that both Paul and Kai made some great points and gave some good suggestions. 

Please take a look at their inputs and provide us with any further questions.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

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