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Npm1100 SHPHLD button shared with GPIO

mccleanp

I am currently developing a board with the npm1100 and nrf52832. I want to make use of the npm1100 ship mode to achieve a very lower power off mode.

I want to use a button connected to SHPHLD to power on again but I also want to connect the same button to a GPIO pin on the MCU.

If the button is connected to both SHPHLD and a GPIO pin I am concerned this will connect VBAT to the MCU and will slowly drain the battery. Also VBAT is 3.7 where as VDD is only 3.0.

I also considered using a simple MOSFET level shifter but I'm concerned this will also drain the battery.

What is the recommended way to share the button input with SHPHLD and a GPIO pin while minimizing power consumption?

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    Hi,

    I know this is an old thread, but I have the same design constraints, so I figured this answer might also be useful to others 

    If you want to have the SHPHLD pin attached to a button that is also attached to the I/O of an MCU you could simply configure the button as active low and use a diode to prevent current from flowing from the SHPHLD pin towards the MCU. 

    Here you can see how that would look like with the button pressed. The MCU voltage is still pulled to a logic low level.

    And here you can see what that would look like with the button unpressed/floating. As you can see there is no current flow

    Kind regards,

    Bram 

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  • 0

    Hi,

    I know this is an old thread, but I have the same design constraints, so I figured this answer might also be useful to others 

    If you want to have the SHPHLD pin attached to a button that is also attached to the I/O of an MCU you could simply configure the button as active low and use a diode to prevent current from flowing from the SHPHLD pin towards the MCU. 

    Here you can see how that would look like with the button pressed. The MCU voltage is still pulled to a logic low level.

    And here you can see what that would look like with the button unpressed/floating. As you can see there is no current flow

    Kind regards,

    Bram 

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