22.6.4.6 Wake-Up Time

The total wake-up time depends on the following:

• Latency due to Power Domain Gating:

  Usually, wake-up time is measured with the assumption that the power domain is already in active state. When using Power Domain Gating, changing a power domain from retention to active state will take a certain time, refer to Electrical Characteristics. If power domain was already in active state in standby sleep mode, this latency is zero. If wake-up time is critical for the application, power domain can be forced to active state in Standby Sleep mode, refer to 22.6.4.1 Power Domain Configuration for details.

• Latency due to Performance Level and Regulator effect:

  Performance Level has to be taken into account for the global wake-up time. As example, if PL2 is selected and the device is in Standby Sleep mode, the voltage level supplied by the ULP voltage regulator is lower than the one used in Active mode. When the device wakes up, it takes a certain amount of time for the main regulator to transition to the voltage level corresponding to PL2, causing additional wake-up time.

• Latency due to the CPU clock source wake-up time.
• Latency due to the NVM memory access.
• Latency due to Switchable Power Domain back-bias wake-up time:

  If back-bias is enabled, and the device wakes up from retention, it takes a certain amount of time for the regulator to settle.