Low power comparator

[PMichael]

Dear Sirs!

I need that low power comparator on input AN7 reset controller when device is in OFF mode when voltage on pin drop below threshold.

Controller powered +1.8V. 

There is +1.8V on AN7. It shall wake up when voltage drop below +1.4V.

Can you please advise or provide an example how to configure low power comparator and event to reach this goal?

Can I assume that input impedance of low power comparator more than 500 KOhm?

Thank you

[Priyanka]

Hi,

Make sure that the comparator you select can operate at low voltages close to its supply voltage (in this case, +1.8V). Also, you need a stable reference voltage of +1.4V to compare against the input voltage on AN7. 

You can set up the  LPCOMP to monitor the AIN7 by configuring the LPCOMP.PSEL register. Set the reference voltage to the desired threshold (in your case, you want the LPCOMP to trigger when the voltage drops below 1.4V). You can do this by using the 15-level internal reference ladder (VDD/16). You would need to select the appropriate level that corresponds to 1.4V. Enable the LPCOMP to be used as a wakeup source from System OFF mode by configuring the LPCOMP to generate events on falling edges of a signal. 
You can check the LPCOMP documentation for further details.

Regards,

Priyanka