HD6473887 Datasheet, PDF (105/523 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer

Section 4 Clock Pulse Generators
4.1 Overview
Clock oscillator circuitry (CPG: clock pulse generator) is provided on-chip, including both a
system clock pulse generator and a subclock pulse generator. The system clock pulse generator
consists of a system clock oscillator and system clock dividers. The subclock pulse generator
consists of a subclock oscillator circuit and a subclock divider.
4.1.1 Block Diagram
Figure 4-1 shows a block diagram of the clock pulse generators.
OSC₁
OSC₂
X₁
X₂
System clock ^øOSC System clock
oscillator
divider (1/2)
(f _OSC)
System clock pulse generator
Subclock
oscillator
ø_W
Subclock
divider
(f_W) _{(1/2, 1/4, 1/8)}
ø_OSC/2
System
clock
divider
ø_W /2
ø_W /4
ø_W /8
ø_OSC/128
ø_OSC/64
ø_OSC/32
ø_OSC/16
ø
Prescaler S
(13 bits)
ø_SUB
Subclock pulse generator
Prescaler W
(5 bits)
Figure 4-1 Block Diagram of Clock Pulse Generators
ø/2
to
ø/8192
ø_W
ø_W /2
ø_W /4
ø_W /8
to
ø_W /128
4.1.2 System Clock and Subclock
The basic clock signals that drive the CPU and on-chip peripheral modules are ø and ø_SUB. Four of
the clock signals have names: ø is the system clock, ø_SUB is the subclock, ø_OSC is the oscillator
clock, and ø_W is the watch clock.
The clock signals available for use by peripheral modules are ø/2, ø/4, ø/8, ø/16, ø/32, ø/64, ø/128,
ø/256, ø/512, ø/1024, ø/2048, ø/4096, ø/8192, ø_W, ø_W/2, ø_W/4, ø_W/8, ø_W/16, ø_W/32, ø_W/64, and
ø_W/128. The clock requirements differ from one module to another.
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