Hello,
I have a question regarding to the behaviour of the PMIC_ON_REQ signal pin in the IMX93 family MPU. The issue is as follows:
I am testing different scenarios where an error may occur and the system must restart. I cannot tolerate the system to poweroff without rebooting again neither shut down the NVCC_BBSM_1V8 voltage, because I need to keep the tamper and RTC functions to keep working.
The iMX93 is MIMX9302CVVxDAB.
The PMIC is PCA9451AHNY.
When a poweroff command from bash is executed, and I must assume that any similar signal that an application or the kernel may generate that resembles to a poweroff, the PMIC_ON_REQ sign is pulled low so that a cold reset is performed and every power rail except from LDO1 are shut down.
I would like to reboot the system without having to disconnect and connect the power supply, it must be something handled by the HW. I have a backup circuit that keeps the NVCC_BBSM_1V8 power rail on when main supply is gone and PMIC falls below UVLO voltage. The thing is that iMX93 does not turn on PMIC_ON_REQ again until NVCC_BBSM_1V8 is shut down and powered again, but as I have already said this is not possible.
I will manage to generate the needed signal to execute the power up sequence in the PMIC with another "PMIC_ON_REQ" signal (use another source that is not the one from iMX93). And my idea is to use the PMIC_ON_REQ from iMX93 to generate a pulse that will assert low PMIC_RST_B pin of PMIC so that a poweroff from bash is interpreted as a reset by the PMIC instead of a poweroff.
My question is as follows, will the iMX93 boot after POR_B is deasserted once the power up cycle is done even if NVCC_BBSM_1V8 hasn't been reclycled and PMIC_ON_REQ hasn't been pulled high bit itself? Remember that I will generate the needed PMIC_ON_REQ needed by the PMIC with other circuit.
I mean, the datasheet says:
I understand that after NVCC_BBSM_1V8 is turned on the PMIC_ON_REQ signal is asserted high and after the power up is completed and POR_B deasserted everything works fine.
But if I don't execute the first two steps will the system boot correctly?
All this stuff is just to avoid unpowering the NVCC_BBSM_1V8 a brief period of time, if another solution is easier, please let me know.
Best regards,
Gorka.
