S3C80A5B
CLOCK CIRCUITS
7-1
7
CLOCK CIRCUITS
OVERVIEW
The clock frequency generated for the S3C80A5B by an external crystal, or supplied by an external clock source,
can range from 1MHz to 8 MHz. The maximum CPU clock frequency, as determined by CLKCON register settings,
is 8 MHz. The X
IN
and X
OUT
pins connect the external oscillator or clock source to the on-chip
clock circuit.
SYSTEM CLOCK CIRCUIT
The system clock circuit has the following components:
— External crystal or ceramic resonator oscillation source (or an external clock)
— Oscillator stop and wake-up functions
— Programmable frequency divider for the CPU clock (f
OSC
divided by 1, 2, 8, or 16)
— Clock circuit control register, CLKCON
X
IN
X
OUT
C1
C2
Figure 7-1. Main Oscillator Circuit
(External Crystal or Ceramic Resonator)
X
IN
X
OUT
External
Clock
Open Pin
Figure 7-2. External Clock Circuit