I am using an external tamper and I set a pull-up resistor connected to VBAT. The tamper circuit is normally tied to ground, and if it is opened, the pull-up issues the tamper signal to VBAT voltage. The VBAT voltage is around 3V.
I mounted a 10k pull-up resistor, the tamper event is issued. However, when I mount a 100k pull-up resistor, the tamper event does not work. I would like to optimise the maximum resistor that makes the tamper work.
My question is which resistor fits the best to get a tamper trigger.