h8s-2172 Renesas Electronics Corporation., h8s-2172 Datasheet - Page 495

• Manufacturer Part Number: h8s-2172
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family H8s-2100 Series
• Manufacturer: Renesas Electronics Corporation.

This LSI has an on-chip clock pulse generator that generates the system clock (φ) and internal
clocks. The clock pulse generator consists of an oscillator circuit and PLL circuit. Figure 15.1
shows a block diagram of the clock pulse generator.
The frequency can be multiplied by two by means of the PLL circuit.
15.1
Clock pulses can be supplied by connecting a crystal resonator, or by input of an external clock.
15.1.1
A crystal resonator can be connected as shown in the example in figure 15.2. Select the damping
resistance R
crystal resonator is used, the range of usable frequencies is from 5 to 16.5 MHz and a crystal
resonator with half frequency of the system clock (φ) should be used.
Figure 15.3 shows the equivalent circuit of the crystal resonator. Use a crystal resonator that has
the characteristics shown in table 15.2.
Oscillator
Connecting Crystal Resonator
d
EXTAL
XTAL
according to table 15.1. An AT-cut parallel-resonance type should be used. When a
Figure 15.1 Block Diagram of Clock Pulse Generator
Section 15 Clock Pulse Generator
Oscillator
PLL circuit
(× 2)
System clock
to φ pin
Rev. 2.00, 03/04, page 463 of 534
Internal clock
to peripheral
modules