
Rev.2.00
Jul 27, 2004
page 72 of 159
REJ03B0091-0200Z
4524 Group
CLOCK CONTROL
The clock control circuit consists of the following circuits.
On-chip oscillator (internal oscillator)
Ceramic resonator
RC oscillation circuit
Quartz-crystal oscillation circuit
Multi-plexer (clock selection circuit)
Frequency divider
Internal clock generating circuit
Fig. 58 Clock control circuit structure
The system clock and the instruction clock are generated as the
source clock for operation by these circuits.
Figure 58 shows the structure of the clock control circuit.
The 4524 Group operates by the on-chip oscillator clock (f(RING))
which is the internal oscillator after system is released from reset.
Also, the ceramic resonator or the RC oscillation can be used for
the main clock (f(XIN)) of the 4524 Group. The CMCK instruction or
CRCK instruction is executed to select the ceramic resonator or
RC oscillator, respectively.
The quartz-crystal oscillator can be used for sub-clock (f(XCIN)).
MR3, MR2
00
01
10
11
QS
QR
QS
R
CRCK instruction
QS
R
CMCK instruction
QS
R
Internal reset signal
XOUT
XIN
Wait time
control circuit
(Note 2)
Program start
signal
Key-on wakeup signal
Notes 1: System operates by the on-chip oscillator clock (f(RING)) until the CMCK or CRCK instruction is executed
after system is released from reset.
2: The wait time control circuit is used to generate the time required to stabilize the f(XIN) or f(XCIN) oscillation.
After the certain oscillation stabilizing wait time elapses, the program start signal is output.
This circuit operates when system is released from reset or returned from power down.
EPOF instruction
POF2 instruction
+
XCOUT
XCIN
QS
R
EPOF instruction
POF instruction
+
T5F flag
MR1
1
MR0
0
System clock (STCK)
Instruction clock
(INSTCK)
Multi-plexer
Quartz-crystal
oscillation circuit
On-chip oscillator
(internal oscillator)
(Note 1)
Ceramic
oscillation circuit
RC oscillation
circuit
Internal clock
generating circuit
(divided by 3)
Divided by 2
Divided by 4
Divided by 8
Division circuit