8-bit AVR Microcontrollers

Clock Systems and Their Distribution

The following figure illustrates the principal clock systems in the device and their distribution. All the clocks need not be active at a given time. In order to reduce power consumption, the clocks to modules not being used can be halted by using different sleep modes. The clock systems are described in the following sections.

The system clock frequency refers to the frequency generated from the system clock prescaler. All clock outputs from the AVR clock control unit runs in the same frequency.

Figure 1. Clock Distribution