HD6433045 HITACHI [Hitachi Semiconductor], HD6433045 Datasheet - Page 642

• Manufacturer Part Number: HD6433045
• Description: Hitachi Single-Chip Microcomputer
• Manufacturer: HITACHI [Hitachi Semiconductor]

19.1 Overview
The H8/3048 Series has a built-in clock pulse generator (CPG) that generates the system clock (ø)
and other internal clock signals (ø/2 to ø/4096). After duty adjustment, a frequency divider divides
the clock frequency to generate the system clock (ø). The system clock is output at the ø pin
furnished as a master clock to prescalers that supply clock signals to the on-chip supporting
modules. Frequency division ratios of 1/1, 1/2, 1/4, and 1/8 can be selected for the frequency
divider by settings in a division control register (DIVCR). Power consumption in the chip is
reduced in almost direct proportion to the frequency division ratio
Notes: 1. Usage of the ø pin differs depending on the chip operating mode and the PSTOP bit
19.1.1 Block Diagram
Figure 19-1 shows a block diagram of the clock pulse generator.
XTAL
EXTAL
2. The division ratio of the frequency divider can be changed dynamically during
setting in the module standby control register (MSTCR). For details, see section 20.7,
System Clock Output Disabling Function.
operation. The clock output at the ø pin also changes when the division ratio is
changed. The frequency output at the ø pin is shown below.
where,
ø = EXTAL n
Oscillator
Figure 19-1 Block Diagram of Clock Pulse Generator
Section 19 Clock Pulse Generator
EXTAL: Frequency of crystal resonator or external clock signal
n:
Frequency division ratio (n = 1/1, 1/2, 1/4, or 1/8)
adjustment
circuit
Duty
633
Frequency
Data bus
Division
register
divider
control
ø pin ø/2 to ø/4096
ø
*2
.
Prescalers
CPG
*1
and