LM2901 with PCA8575

Hi, I have designed a Non inverting comparator circuit with LM2901. The inverting input has 0.5V as Vref through a potential divider. The non inverting input is the signal input, which has 10K input resistor and a 390K feedback resistor to get 100mV hysteresis. The output has a 10K pull up and it is connected to a IO expander PCA8575 through a 0 ohm resistor. I am seeing a strange behavior of the comparator output. During power up, if the +input is 0V then the output is stuck at low. after power up, the change in the +input higher than Vref is not changing the state. However if the input is higher than Vref at the power up then the output is toggling high and low as expected. Can anyone help to explain what is happening here, and how to solve this issue?

by Sacra
December 11, 2021

Hope this would help you, you can find the LM2901 datasheet here: https://www.easybom.com/p/lm2901d-texas-instruments-3420391

by poppocat
December 21, 2021

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