# Low Power Callback¶

group group_sysclk_pm

Entering and exiting low power modes require compatible clock configurations to be set before entering low power and restored upon wake-up and exit.

The SysClk driver provides a Cy_SysClk_DeepSleepCallback() function to support Deep Sleep mode entry.

This function can be called either by itself before initiating low-power mode entry or it can be used in conjunction with the SysPm driver as a registered callback. To do so, register this function as a callback before calling Cy_SysPm_DeepSleep(). Specify CY_SYSPM_DEEPSLEEP as the callback type, and call Cy_SysPm_RegisterCallback().

note

If the FLL or PLL source is the ECO, this function must be called.