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CLOCK GENERATING CIRCUIT
14.1 Oscillation circuit example
This chapter describes a clock generating circuit which supplies the operating clock of the central processing
unit (CPU), bus interface unit (BIU), or internal peripheral devices.
The clock generating circuit contains the oscillation circuit.
14.1 Oscillation circuit example
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. The example of the oscillation circuit is described below.
14.1.1 Connection example using resonator/oscillator
Figure 14.1.1 shows an example when connecting
a ceramic resonator/quartz-crystal oscillator between
pins X
and X
.
IN
OUT
The circuit constants such as R
(shown in Figure 14.1.1) depend on the resonator/
oscillator. These values shall be set to the resonator/
oscillator manufacturer's recommended values.
14.1.2 Input example of externally generated clock
Figure 14.1.2 shows an input example of the clock
which is externally generated. The external clock
must be input from the X
must be left open.
14–2
, R
, C
, and C
f
d
IN
OUT
pin, and the X
pin
IN
OUT
7751 Group User's Manual
X
IN
C
Fig. 14.1.1 Connection example using resonator/oscillator
X
IN
Externally generated clock
V
CC
V
SS
Fig. 14.1.2 Externally generated clock input example
M37751
X
OUT
R
f
R
d
C
IN
OUT
M37751
X
OUT
Open
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