7220 Datasheet, PDF (127/303 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCOMPUTER

FUNCTIONAL DESCRIPTION
2.16 Clock generating circuit
2.16 Clock generating circuit
Oscillation circuit consists of an “oscillation gate” which operates as an amplifier to provide the gain required
for oscillation and an “oscillating control flip-flop” to control this. Because of that, it is possible to start and
stop oscillating as required. For details concerning start and stop of oscillation, refer to “2.14 Low-power
dissipation mode.” Figure 2.16.1 shows the clock generating circuit block diagram.
Interrupt request
Interrupt disable
flag I
Reset
STP instruction
SQ
R
SQ
WIT
R
instruction
QS
Reset
R STP
instruction
.
Selection gate :
Connected to black
side at reset.
1/2
1/8
XIN
T34M : Timer 34 mode register
XOUT
T34M0
T34M2
Timer 3
Internal clock φ
Timer 4
Fig. 2.16.1 Clock generating circuit block diagram
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7220 Group User’s Manual