Data Sheet

3.7 RTC and Low-Power Management 3 FUNCTIONAL DESCRIPTION
3.7 RTC and Low-Power Management
With the advanced power management technologies, ESP32 can switch between different power modes (see
Table 4).
• Power mode
– Active mode: The chip radio is powered on. The chip can receive, transmit, or listen.
– Modem-sleep mode: The CPU is operational and the clock is configurable. The Wi-Fi/Bluetooth base-
band and radio are disabled.
– Light-sleep mode: The CPU is paused. The RTC and ULP-coprocessor are running. Any wake-up
events (MAC, host, RTC timer, or external interrupts) will wake up the chip.
– Deep-sleep mode: Only RTC is powered on. Wi-Fi and Bluetooth connection data are stored in RTC
memory. The ULP-coprocessor can work.
– Hibernation mode: The internal 8MHz oscillator and ULP-coprocessor are disabled. The RTC recovery
memory are power-down. Only one RTC timer on the slow clock and some RTC GPIOs are active. The
RTC timer or the RTC GPIOs can wake up the chip from the Hibernation mode.
• Sleep Pattern
– Association sleep pattern: The power mode switches between the active mode and Modem-sleep/Light-
sleep mode during this sleep pattern. The CPU, Wi-Fi, Bluetooth, and radio are woken up at predeter-
mined intervals to keep Wi-Fi/BT connections alive.
– ULP sensor-monitored pattern: The main CPU is in the Deep-sleep mode. The ULP co-processor does
sensor measurements and wakes up the main system, based on the measured data from sensors.
Table 4: Functionalities Depending on the Power Modes
Power mode Active Modem-sleep Light-sleep Deep-sleep Hibernation
Sleep pattern
Association sleep pattern
ULP sensor-
monitored pattern
-
CPU ON PAUSE ON OFF OFF
Wi-Fi/BT base-
band and radio
ON OFF OFF OFF OFF
RTC ON ON ON ON OFF
ULP co-processor ON ON ON ON/OFF OFF
The power consumption varies with different power modes/sleep patterns and work status of functional modules
(see Table 5).
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