HD6417034B RENESAS [Renesas Technology Corp], HD6417034B Datasheet - Page 123

• Manufacturer Part Number: HD6417034B
• Description: 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

7.1
The SuperH microcomputer has a built-in clock pulse generator (CPG) that supplies the chip and
external devices with a clock pulse. The CPG makes the chip run at the oscillation frequency of
the crystal resonator. The CPG consists of an oscillator and a duty cycle correction circuit (figure
7.1). The CPG can be made to generate a clock signal by connecting it to a crystal resonator or by
inputting an external clock. (The CPG is halted in standby mode.)
7.2
Clock pulses can be supplied from a connected crystal resonator or an external clock.
7.2.1
Circuit Configuration: A crystal resonator can be connected as shown in figure 7.2. Use the
damping resistance Rd shown in table 7.1. Use an AT-cut parallel resonating crystal with a
frequency equal to the system clock (CK) frequency. Connect load capacitors (C
shown in the figure. The clock pulse produced by the crystal resonator and internal pulse generator
is sent to the duty cycle correction circuit where its duty cycle is corrected. It is then supplied to
the chip and to external devices.
System clock
Overview
Clock Source
Connecting a Crystal Resonator
EXTAL
XTAL
Section 7 Clock Pulse Generator (CPG)
CK
Figure 7.1 Block Diagram of Clock Pulse Generator
Oscillator
correction circuit
Duty cycle
Section 7 Clock Pulse Generator (CPG)
Rev. 7.00 Jan 31, 2006 page 97 of 658
CPG
REJ09B0272-0700
L1
Internal
clock ( )
and C
L2
) as