DocID024130 Rev 2

9/22

AN4231

STANDBY Mode transition

2

STANDBY Mode transition

Once STANDBY is entered, it is only left via a system wakeup. On exiting the STANDBY

mode, all power domains are powered up according to the settings in the PCU_PCONFn

registers, and the DRUN mode is entered. In DRUN mode, at least power domains 0 and 1

are powered.

Figure 3, shows an example for a mode transition from RUN0 to STANDBY to DRUN. All

power domains which have PCU_PCONFn.STBY cleared enter power-down phase. In this

example, only power domain 1 is disabled during STANDBY mode.

When the MC_PCU receives the mode change request to STANDBY mode, it starts the

power down phase for power domain 1. During the power down phase, clocks are disabled

and reset is asserted resulting in a loss of all the information for this power domain. Then

the power domain is disconnected from the power supply (power-down state).

Figure 3. MC_PCU Events During Power Sequences (STANDBY mode)

When the MC_PCU receives a system wakeup request, it starts the power-up phase. The

power domain is re-connected to the power supply and the voltage in power domain 1

increases slowly. Once the voltage is in an operable range, clocks are enabled and the reset

is deasserted (power-up state).

GAPGRI00364