7905 datasheet(63/565 Pages) RENESAS

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CLOCK GENERATING CIRCUIT

7905 Group User’s Manual Rev.1.0

4-2

4.1 Oscillation circuit examples

To the oscillation circuit, a ceramic resonator or a quartz-crystal oscillator can be connected, or the clock

which is externally generated can be input. Oscillation circuit examples are shown below.

4.1.1 Connection example with resonator/oscillator

Figure 4.1.1 shows an example where pins XIN and XOUT connect across a ceramic resonator/quartz-crystal

oscillator.

The circuit constants such as Rf, Rd, CIN, and COUT (shown in “Figure 4.1.1”) depend on the resonator/

oscillator. These values shall be set to the values recommended by the resonator/oscillator manufacturer.

Fig. 4.1.1 Connection example of resonator/oscillator

Fig. 4.1.2 Externally generated clock input example

M37905

XIN

XOUT

CIN

COUT

M37905

XIN

XOUT

Vcc

Vss

Externally generated clock

Open

4.1.2 Externally generated clock input example

Figure 4.1.2 shows an input example of a clock which is externally generated. An external clock must be

input from pin XIN, and pin XOUT must be left open.

When an externally generated clock is input, the power source current consumption can be saved by the

stop of internal circuit’s operation between pins XIN and XOUT. (Refer to “CHAPTER 16. POWER SAVING

FUNCTION.”)

7905 Datasheet(PDF) 63 Page - Renesas Technology Corp