SPRADO2 November 2024 AM62A3 , AM62A3-Q1 , AM62A7 , AM62A7-Q1
The recommendation is to provision for a software-enabled (controlled) power switch (load switch) that sources the SD card power supply (VDD). A fixed 3.3V supply (IO supply connected to the processor) is connected as an input to the power switch.
Use of power switch allows power cycling of the SD card (since resetting SD card power is the only way to reset the SD card) and resetting the SD card back to the reset state.
Recommendation is to implement the SD card power switch enable reset logic using a three input ANDing logic. One of the AND gate input is connected to the processor general purpose input/output (GPIO). One of the AND gate input has provision for pullup (to support boot) near to the input and 0Ω to isolate the GPIO for testing or debug. The other two AND gate inputs are connected to the main domain POR (cold reset) status output (PORz_OUT) and main domain warm reset status output (RESETSTATz) signals.
If the SD card is configured as a boot device, the external power switch sourcing the SD card power supply must default to ON (powered state).
For the implementation details, see the device-specific SK.