Hello,

I draw a circuit for Power switching.
I wonder Pwr_key_det is good?

 

How can we tell if it is good or not? What is it supposed to do?

 

Thank you for reply~

My intended sequence of actions is as follows:
1. Push the button (SW440) for a while
2. The Gate of P-CH FET goes Low, SYS_PWR_EN goes High
3. PS_HOLD goes High by MCU
4. SYS_PWR_EN remains High when the switch(sw440) is released.

after that,
I want the MCU to be able to detect when a switch(sw440) is pressed, through the PWR_KEY_DET

 

Thank you for reply~

My intended sequence of actions is as follows:
1. Push the button (SW440) for a while
2. The Gate of P-CH FET goes Low, SYS_PWR_EN goes High
3. PS_HOLD goes High by MCU
4. SYS_PWR_EN remains High when the switch(sw440) is released.

after that,
I want the MCU to be able to detect when a switch(sw440) is pressed, through the PWR_KEY_DET

What happens if the switch(sw440) bounces for 20-50 milliseconds? Is that going to cause a problem?

 

What is the battery voltage VBATT?
D400 has a clamp voltage of 3.3V, which will conduct if the VBATT voltage is >3.3V and possibly turn on the MOSFET.

 

PWR_KEY_DET is pulled low via D652 when the key is operated (so it is active LOW), but there is no pullup to return it HIGH (inactive) when the key is released, unless the MCU pin has a pullup internally.

 

after that,
I want the MCU to be able to detect when a switch(sw440) is pressed, through the PWR_KEY_DET

If the purpose is to power OFF with a second push of the switch you will need to program a delay on this action when first powered ON.