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Mitsubishi microcomputers
M16C / 6N0 / 6N1 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
36
Clock Generating Circuit
The clock generating circuit contains three oscillator circuits that supply the operating clock sources to the
CPU and internal peripheral units.
Figure 1.10.1. Examples of main clock
Figure 1.10.2. Examples of sub clock
Example of Oscillator Circuit
Figure 1.10.1 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 1.10.2 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 Figures 1.10.1 and 1.10.2 vary with each oscillator used. Use
the values recommended by the manufacturer of your oscillator.
Table 1.10.1. Main clock and sub clock generating circuits
Clock Generating Circuit
Main clock generating circuit
Sub clock generating circuit
Use of clock
Oscillator status immediately after reset
Stopped
Pins to connect oscillator
Usable oscillator
Ceramic or quartz crystal oscillator
XIN, XOUT
Available
Oscillating
Quartz crystal oscillator
XCIN, XCOUT
Oscillation stop/restart function
Available
Other
Externally derived clock can be input
CPU’s operating clock source
Internal peripheral unit’s operating clock source
CPU’s operating clock source
Timer A/B’s count clock source
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
Externally derived clock
Open
Vcc
Vss
Microcomputer
(Built-in feedback resistor)
XIN
XOUT
Rd
CIN
COUT
(Note)
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. Also if the oscillator manufacturer’s
data sheet specifies that a feedback resistor be added external to the chip, insert a feedback resistor between XIN
and XOUT following the instruction.
Microcomputer
(Built-in feedback resistor)
XCIN
XCOUT
Externally derived clock
Open
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. Also if the oscillator manufacturer’s
data sheet specifies that a feedback resistor be added external to the chip, insert a feedback resistor between XIN
and XOUT following the instruction.
Microcomputer
(Built-in feedback resistor)
XCIN
XCOUT
(Note)
CCIN
CCOUT
RCd