Regarding the issue of NRF82805 chip being unable to restart after turning off the switch

[yangyt]

When using the hall or switch button to open the power, the product cannot start. At present, the measured VDD voltage is 3.1V. After pressing the button, the switch control is normal and has dropped to 0.3V,The device cannot turn on the power. Our products are not use  low -frequency crystal oscillators and use internal RC chips. If the power supply is disconnected, it can be restored to OK

[Sigurd]

Hi!

Do you have any schematics that shows how this power button is connected ?

[yangyt]

This switch control signal is P0.12_KEY 

[JONATHAN LL]

How many units show this issue? is it only one or are there multiple that show same behaviour\issue? 

I see no issues with the Schematic for the nRF52, but what is the voltage you measure on the OUT (pin2) on the hall switch. is that the 0.3V ?

Regards,
Jonathan

[hmolesworth]

With a push-pull output (as opposed to an open-drain output) on KTH1701 OUTPUT the circuit will not behave as expected. If the high-side FET is (say) 200 Ohm or less when the output is high, pressing the button will change the voltage on P0.12_KEY from VDD to (220/(220+200))xVDD = 0.5xVDD. The P0.12 input pin requires below 0.3xVDD to detect a low signal indicating a button press, so the button press will not be detected. If OUTPUT is always low, again the button press will not be detected.

In short the button press does nothing detectable. Fix this by inserting a series schottky diode from KTH1701 OUTPUT pin such that the sensor can pull P0.12_KEY low but not hold P0.12_KEY high so now the button press can generate a low signal on P0.12.