4501 datasheet(167/212 Pages) RENESAS

167 / 212 page

2.8 Oscillation circuit

2-50

Rev.2.01

Feb 07, 2005

4501 Group

APPLICATION

REJ09B0192-0201

(3)

Ceramic resonator

When the ceramic resonator is used as the

source oscillation (f(XIN)), connect the ceramic

resonator and the external circuit to pins XIN

and XOUT at the shortest distance. Then,

execute the CMCK instruction. A feedback

resistor is built in between pins XIN and XOUT

(Figure 2.8.3).

As for the oscillation frequency, do not exceed

the values shown in the Table 2.8.1.

Fig. 2.8.3 Ceramic resonator external circuit

4501

XIN

XOUT

CIN

COUT

Execute the CMCK instruction in

program.

Note: Externally connect a damping

resistor Rd depending on the

oscillation frequency.

(A feedback resistor is built-in.)

Use the resonator manu-

facturer’s recommended value

because constants such as

capacitance depend on the

resonator.

Supply voltage

2.7 V (Note) to 5.5 V

(System clock)

(f(XIN))

High-speed mode

(f(XIN)/2) Middle-speed mode

(f(XIN)/4) Low-speed mode

(f(XIN)/8) Default mode

Oscillation frequency

4.4 MHz

Note: System is in the reset state when the value is under the detection voltage.

Table 2.8.1 Maximum value of oscillation frequency and supply voltage

(4)

RC oscillation

When the RC oscillation is used as the source

oscillation (f(XIN)), connect the XIN pin to the

external circuit of resistor R and the capacitor

C at the shortest distance and leave XOUT

pin open. Then, execute the CRCK instruction

(Figure 2.8.4).

The frequency is affected by a capacitor, a

resistor and a microcomputer.

So, set the constants within the range of the

frequency limits.

Fig. 2.8.4 External RC oscillation circuit

4501

XIN

XOUT

Execute the CRCK

instruction in program.

4501 Datasheet(PDF) 167 Page - Renesas Technology Corp

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