4524 datasheet(85/310 Pages) RENESAS

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4524 Group

HARDWARE

Rev.2.00

Aug, 06 2004

REJ09B0107-0200Z

1-72

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

CRCK instruction

CMCK instruction

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

EPOF instruction

POF instruction

T5F flag

MR1

MR0

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

FUNCTION BLOCK OPERATIONS

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