S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X CLOCK CIRCUIT
7-1
7 CLOCK CIRCUIT
OVERVIEW
The S3C8275X/C8278X/C8274X microcontroller has two oscillator circuits: a main clock and a sub clock circuit.
The CPU and peripheral hardware operate on the system clock frequency supplied through these circuits. The
maximum CPU clock frequency of S3C8275X/C8278X/C8274X is determined by CLKCON register settings.
SYSTEM CLOCK CIRCUIT
The system clock circuit has the following components:
• External crystal, ceramic resonator, RC oscillation source, or an external clock source
• Oscillator stop and wake-up functions
• Programmable frequency divider for the CPU clock (fxx divided by 1, 2, 8, or 16)
• System clock control register, CLKCON
• Oscillator control register, OSCCON and STOP control register, STPCON
• Clock output control register, CLOCON
CPU Clock Notation
In this document, the following notation is used for descriptions of the CPU clock;
fx: main clock
fxt: sub clock
fxx: selected system clock
