Q1: Do I have to chance to update data to registers via I2C before power-on sequence? For example, connect all VIN pins and AVIN pin with 5v power, but keep PWRON low. Is this a state that I2C works, but the system has not yet generate power output on those output PINs?
Q2: The data sheet mentions that OUTRTC LDO is always on as long as both VIN2 and AVIN are connected with power. Is this true when PWRON is low?
Q3: What is the max voltage for I2C PINs?
I am considering a use case: use a small MCU to manage MPQ7920. MCU is powered by MPQ7920’s OUTRTC (put PWRON low, supply 5v power to all VIN/AVIN PINs.). Once MCU is booted, it connects to MPQ7920 via I2C interface, and modify registers to adjust Buck/LDO’s output voltages and power-on sequences. and then MCU will set MPQ7920’s PWRON pin to high to power-on other Bucks/LDOs. This will give host SoC required power. MCU will then change itself from I2C master to I2C slave. And then both MCU and MPQ7920 will be managed by host SoC.
