Resetting boron from "power connected" state

I have kind of an odd project here where the device has two different modes depending on whether or not it senses voltage. In no-power mode it sleeps most of the time (on battery), and occasionally wakes up for a check-in.

But when power is applied to the sense line the device needs to wake up and start a more active process immediately. My solution was to have a simple RC circuit generate a pulse to pull EN to ground for a moment and cause the device to reboot. Schematic attached…

The thing is, this works perfectly if the device is awake, but not at all once the device is asleep. Physically grounding the EN for a moment does work, but the short pulse through a mosfet doesn’t seem to do the trick…guessing something just stays charged up in the EN pullup that would normally be drained off quickly when the boron is awake?

Really just looking for any ideas/advice here, having a ‘stuck’ week :confused:

Highlighed the important part of the circuit: R10/R19 effectively make a divider to drop 12+ down to 3ish for the sake of the mosfet, RDS-on is 1v. Can/have scoped a lot of stuff if there’s a good test someone has in mind.

Couple scope shots to show generated pulse at pin1 of the mosfet, and the voltage across EN while in sleep mode. Time scale is the same, voltage scale is not. Dip in V on the mosfet pin is dicharge once power is removed:


EN pin

Future explorers: solved by changing R10 to 22k, which ups the voltage going to Q3N to create a slightly longer grounding pulse by extending the time pin1 is above threshold. For whatever reason it needs that in sleep, but not in other modes. :man_shrugging:

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