I am designing a simple circuit for weight controller and I am not sure where I should connect the drain of N-channel mosfet. My goal is to design a circuit that when powered off (both when button BN1 and pin B6 are low) should be inactive and drain nearly zero amperes (few microampers is fine). One of my attempts look in a following way:
+12V and FGND is where a 12V acid battery will be connected to, and VCC (3.3V) and +5V are outputs of voltage regulators. The R25 and C23 duo form low pass filter to prevent double clicks when clicking the buttons. R22 is there just to provide a way to discharge capacitors C28/C30/C27/C25, but I am not sure if it is helping much.
I am not confident about this design choice. Especially what happens when both MOSFETs are turned off and ground slowly reaches 12V - what exactly will happen to the outputs of the voltages regulators? Will The PD across VCC/GND go negative? Can this negative PD cause damage to the unipolar capacitors C27 and C28? How can I improve this design?
My second design, which looks a little better to me:
12V battery is connected to +12V/GND, RelativeGND is connected to the voltage regulators.
I don't like how the voltage regulators work with two different grounds. For input, the relative ground is used, and for output the real GND should be used, but I feel like this is not how the voltage regulators work, and that this may give me slightly increased PD across VCC/GND and 5V/GND pairs than the datasheet describes. Any feedback?