We are following the power-up sequence as described in 4.2.1.1 of RT1050 Data Sheet rev 2 3/2021. The question is about the NOTE stating "Need to ensure that there is no backvoltage (leakage) from any supply on the board towards V supply ( for example, from external components that use both the 1.8V and 3.3V supplies)" In our design we are using 3.3V, except for the 1.8V only on the NVCC_SD1 power that is hooked up to only a SPI NOR_FLASH. The 1.8V comes from an LDO that is supplied from the same 3.3V as the RT1052, hence ramping up together with the 3.3V at power-up. Our schematics:
1) Is ramping 1.8V together with 3.3V (or slightly after) OK?
2) Or does the note imply that 1.8V must ramp before 3.3V? And care must be taken that 1.8V does not leak into 3.3V to either disrupt the order or making the ramp discontionous?
Thanx.
