M16C6K9 Datasheet, PDF (30/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
Clock Generating Circuit
Clock Generating Circuit
The clock generating circuit contains two oscillator circuits that supply the operating clock sources to the
CPU and internal peripheral units.
Table.WA-1 Main clock and sub clock generating circuits
Use of clock
Usable oscillator
Pins to connect oscillator
Oscillation stop/restart function
Oscillator status immediately after reset
Other
Main clock generating circuit
Sub clock generating circuit
• CPU’s operating clock source • CPU’s operating clock source
• Internal peripheral units’
• Timer A/B’s count clock
operating clock source
source
Ceramic or crystal oscillator
Crystal oscillator
XIN, XOUT
XCIN, XCOUT
Available
Available
Oscillating
Stopped
Externally derived clock can be input
Example of oscillator circuit
Fig.WA-1 shows some examples of the main clock circuit, one using an oscillator connected to the circuit,
and the other one using an externally derived clock for input. Figure WA-2 shows some examples of sub
clock circuits, one using an oscillator connected to the circuit, and the other one using an externally derived
clock for input. Circuit constants in Fig.WA-1 and WA-2 vary with each oscillator used. Use the values
recommended by the manufacturer of your oscillator.
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
(Note)
Rd
CIN
COUT
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
Open
Externally derived clock
Vcc
Vss
Note: Insert a damping resistor if required. The resistance will vary depending on the oscillator and the oscillation drive
capacity setting. Use the value recommended by the maker of the oscillator.
When the oscillation drive capacity is set to low, check that oscillation is stable.
Apply the feedback register between XIN and XOUT if required by oscillator maker.
Fig.WA-1 Examples of main clock
Microcomputer
(Built-in feedback resistor)
XCIN
XCOUT
(Note)
RCd
CCIN
CCOUT
Microcomputer
(Built-in feedback resistor)
XCIN
XCOUT
Open
Externally derived clock
Vcc
Vss
Note: Insert a damping resistor if required. The resistance will vary depending on the oscillator and the oscillation drive
capacity setting. Use the value recommended by the maker of the oscillator.
When the oscillation drive capacity is set to low, check that oscillation is stable.
Apply the feedback register between XCIN and XCOUT if required by oscillator maker.
Fig.WA-2 Examples of sub clock
Rev.1.00 Jun 06, 2003 page 30 of 290