The K26 SOM provides a mechanism to power down all SOM power rails from software via the Zynq UltraScale+ MPSoC power management unit (PMU). The MIO34 pin on the Zynq UltraScale+ MPSoC is connected to the power shutdown request of the SOM power sequencer on the board. The power sequencer device sequences down all supplies when it observes a transition from a logic-High to a logic-Low state. On power up, the power sequencer ignores the shutdown request signal until after the POR_B is released. For additional PMU firmware guidance, see the Kria SOM Wiki.