29.5.3 Clocks

The AC bus clock (CLK_AC_APB) can be enabled and disabled in the Main Clock module, MCLK (see MCLK - Main Clock, and the default state of CLK_AC_APB can be found in Peripheral Clock Masking.

Two generic clocks (GCLK_AC_DIG and GCLK_AC_ANA) are used by the AC. The digital clock (GCLK_AC_DIG) is required to provide the sampling rate for the comparators, while the analog clock (GCLK_AC_ANA) is required for low voltage operation (VDDANA < 2.5V) to ensure that the resistance of the analog input multiplexors remains low. These clocks must be configured and enabled in the Generic Clock Controller before using the peripheral.

This generic clock is asynchronous to the bus clock (CLK_AC_APB). Due to this asynchronicity, writes to certain registers will require synchronization between the clock domains. Refer to Synchronization for further details.