4559 datasheet(61/148 Pages) RENESAS

61 / 148 page

Rev.1.04

Aug 23, 2007

Page 61 of 146

REJ03B0188-0104

4559 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

The system clock and the instruction clock are generated as the

source clock for operation by these circuits.

Figure 59 shows the structure of the clock control circuit.

The 4559 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 4559 Group.

The quartz-crystal oscillator can be used for sub-clock (f(XCIN)).

Fig 59. Clock control circuit structure

MR3, MR2

Q S

Timer 3 underflow signal

EPOF instruction +

XCOUT

XCIN

EPOF instruction +

MR1,MR0

System clock (STCK)

Instruction clock

(INSTCK)

Multi-

plexer

Quartz-crystal

oscillation

On-chip oscillator

(internal oscillator)

XOUT

XIN

Ceramic

resonance

RC oscillation

Internal clock

generating circuit

(divided by 3)

RG1

RG0

RG2

Divided by 2

Divided by 4

Divided by 8

Division circuit

CRCK instruction

Internal reset signal

Key-on wakeup signal

POF instruction

POF2 instruction

4559 Datasheet(PDF) 61 Page - Renesas Technology Corp

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