14.4.3.1 Regulator Automatic Low-Power Mode

In Standby sleep mode, the PM selects either the Low Voltage Regulator (LDO) or the Ultra-Low Power (ULP) voltage regulator to supply the VDDCORE. By default, the ULP voltage regulator is used.

If a sleepwalking peripheral requests a clock source other than a slow clock (e.g., 32 kHz), the LDO regulator is automatically enabled during the sleepwalking operation. This behavior can be changed by writing the SUPC.VREG.RUNSTDBY bit. Refer to the following table for details.

Table 14-1. Regulator State in Sleep Mode
Sleep ModeSUPC.VREG.RUNSTDBYSleepWalkingRegulator Used for VDDCORE
Active--ULP/LDO(1)
Idle--ULP/LDO(1)
Standby0x0: AutoNoULP
YesULP/LDO(2)
0x1: Performance-LDO
Note:
  1. If the CPU or a peripheral requests a “fast” clock, the LDO is automatically enabled. In Active mode, the LDO is also used if SUPC.VREG.RUNSTDBY is set to Performance. Otherwise, the ULP is used.
  2. During sleepwalk, if a peripheral requests a “fast” clock, the LDO is automatically enabled for the duration of the sleepwalk. Otherwise, the ULP is used.