I'm coming on-board to a new design using the i.MXRT1051DVL6A where the A0 silicon was specified in the BoM and the board was designed with 3V3 on the DCDC-In rail.
Looking in the datasheet, this rail appears to still have an Absolute Maximum rating that seems like it should withstand > 3V0 volts on DCDC-IN, but two boards that I'm working with draw so much current when 3V3 is put on the NVCC-* rails that the LDOs end-up current limiting and shunt the 3V3 rail to about 0.7V.
I've made a small mod where I put a diode in series to the DCDC-IN rail to try and limit it to ~3V but as soon as NVCC is connected the 3V3 rail tanks.
We can't wait for a board spin and are thinking of replacing the BGA MCU using a turnkey but wanted an opinion if 3V3 on A0 silicon will damage the MCU or if we should ensure that hardware mods are performed before powering-up the MCU after replacement.
I've isolated the SDRAM supply and the flash supply is connected to 3V3 directly; all told, it comes down to connecting the NVCC lines to the MCU where the overcurrent happens.
Scott Thompson, TC Helicon