On Dev kit SCH P3737_A04 page 6 regarding power-on MCU, there are two output signals - one is VIN_PWR_ON to enable SYS_VIN_HV/MV and another one is MODULE_POWER_ON to enable module to power up. I believe MODULE_POWER_ON must be asserted after VIN_PWR_ON is asserted.
What input signals of MCU shall be asserted to trigger MCU asserting VIN_PWR_ON?
What input signals of MCU shall be asserted to trigger MCU asserting MODULE_POWER_ON?
Does MCU just wait for a fixed certain time to assert MODULE_POWER_ON after VIN_PWR_ON is asserted? Or after VIN_PWR_ON is asserted, MCU still needs to check some signals level as required before assert MODULE_POWER_ON? what are those signals?
I agree that if vddin_pwr_bad_n goes low it will turn down module_power_on. However, on Dev kit SCH P3737_A04, during power up, vddin_pwr_bad_n is pulled up to high as soon as VCC_SRC_FET (U69) is ready which happens much earlier than vin_pwr_on is set “on” by power button. That means after vddin_pwr_bad_n is high, module_power_on will NOT be set high right away but still waiting for Button MCU to set it high. So I assume U79 (Button MCU) particularly set a time delay between vin_pwr_on event and module_power_on event, which is about 80ms from DG. Button MCU will set module_power_on high 80ms afer vin_pwr_on is high.
Would you confirm that is correct?
Another question, Why is this delay T_MPO set as 80ms?
VDDIN_PWR_BAD_N should go up at the same time as MV. Because it’s pulled up thru 10k by MV on module. The carrier board P3737 doesn’t drive it high. P3737 can only drive it low or leave it as is.
It’s defined in button MCU FW. Not sure about why set 80ms. The purpose is to get HV/MV ready before enable MODULE_POWER_ON. The button MCU FW applies to many jetson projects. For other projects, VIN_PWR_ON will control the buck/boost converter for HV/MV. It will need more time to get ready compared to Concord.