19.3.2.2 Voltage Regulator Configuration
A voltage regulator is used to regulate the core voltage. The regulator can be configured to balance power consumption, wake-up time from sleep, and maximum clock speed.
The Power Mode (PMODE) bit field in the Voltage Regulator Control (SLPCTRL.VREGCTRL) register is, by default, configured to automatically switch the regulator to low-power mode in sleep mode when OSC32K is the only oscillator enabled and UPDI is inactive. In the low-power mode, the regulator consumes less power but is limited in the amount of current it can provide, which, in turn, limits the clock frequency it can support. A maximum-performance power mode can also be selected using the PMODE bit field. The two modes are described in the following table:
| Voltage Regulator Power Mode | Description | Condition | Active/Idle | Standby(1) | Power-Down |
|---|---|---|---|---|---|
| Normal (AUTO) | Maximum performance in Active mode and Idle mode. Power saving in Standby mode and Power-Down mode. | Internal oscillator with fCLK > 32.768 kHz, external clock, or UPDI active | Maximum Performance | Low Power | Low Power |
| fCLK ≤ 32.768 kHz and UPDI inactive | Low Power | ||||
| Performance (FULL) | Maximum performance in all modes (Active mode and any Sleep mode) and fast start-up from all sleep modes | Any clock source | Maximum Performance | Maximum Performance | Maximum Performance |
- If any peripheral requests an External clock/XOSCHF or an internal clock faster than fCLK > 32.768 kHz, or UPDI is active, the power voltage regulator switches to Maximum Performance, also in Normal mode (AUTO).
The VMON in Sleep Mode (VSLP) flag in the Interrupt Flags (INTFLAGS) register will permanently be set when selecting OSC32K as the main clock source with UPDI inactive. Configure the Error Controller so that this does not cause an unwanted response, such as entering a safe state.
The VMON Sleep Mode Enable (VMONSEN) bit in the Voltage Regulator Control (SLPCTRL.VREGCTRL) register can be configured to either monitor the voltage regulator in Standby and Power-Down sleep modes or to be disabled in Standby and Power-Down sleep modes. Enabling VMONSEN in these sleep modes offers protection from Voltage Regulator failure but will increase the power consumption.