SPRADN4B October 2024 – September 2025 AM62P , AM62P-Q1
The recommendation is to provide provision for a software-enabled (controlled) power switch (load switch) that sources the power supply (VDD) to the SD card. A fixed 3.3V supply (processor IO supply) is connected as the input to the power switch.
Use of power switch allows power cycling of the SD card supply (since resetting the power switch is the only way to reset the SD card) and resetting the SD card to the default state when UHS-I SD card is used.
The recommendation is to implement the SD card power switch enable and reset logic using a 3-input ANDing logic. Processor GPIO is connected as one of the input to the AND gate with provision for pullup (10kΩ or 47kΩ) (to support SD card boot) near to the ANDing logic AND gate and provision for 0Ω to isolate the GPIO output for testing or debug. The other two inputs to the AND gate are the MAIN domain POR (cold reset) status output (PORz_OUT) and MAIN domain warm reset status output (RESETSTATz).
The external power switch sourcing the SD card power supply is recommended to default to ON (powered state) to support SD card boot.
For implementation, see the processor-specific SK.