PCA9450 PMIC_NINT pin behavior

[mobrien]

I'm working on a design using the PCA9450. The system is up and running, and seems fine, but the PMIC_NINT pin is held low all the time except for about 1 second after power in it is driven to 0.4V for 10 milliseconds. This coincides with an I2C command send to the chip.

We are using the NXP provided driver and have the pin connected to GPIO1_IO03 - same as the reference design. Once difference we have is that the pin is pulled up to 3.3V since we have GPIO1 NVCC pin connected to 3.3. The pullup value is 100K.

Is this pin used by the PMIC driver at all? How can it get driven to 0.4V?

The net has three connections: PCA9450 pin 13 (IRQ_B), i.MX8M Mini Ball AF13 (GPIO1_IO03), and a 100K pullup to 3.3V. Ball W12 (NVCC_GPIO1) is connected to VDD_3V3 -   which is the output of Buck 4.

Thanks

-Mike

[weidong_sun]

Hello Michael,

On i.MX8MM-EVK(the version of PCA9450 + I.MX8MM), 1.8V for the pin is used. And on the page of "i.MX8M Mini IO Interface", you can find warning below if 3.3V is used:

So it means that you will have to re-configure the PAD register to disable PU/PD features in device tree.

Hope the information is helpful to you.

Have a nice day!

B.R,

Weidong