M30222 Datasheet, PDF (20/237 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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MITSUBISHI MICROCOMPUTERS
Specifications in this manual are tentative and subject to change
M30222 Group
Rev. G
Clock Generating Circuit
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
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 1.10 shows some examples of the main clock and
subclock generating circuits.
Table 1.10. Main clock and sub-clock generating circuits
Main clock generating circuit
Use of clock
Operating clock source for CPU
Operating clock source for Internal
peripheral
Usable oscillator
Ceramic or crystal oscillator
Pins to connect oscillator
Xin, Xout
Oscillation stop/restart function Available
Oscillator status immediately
after Reset
Oscillating
Other
Externally derived clock can be input (Note)
Sub-clock generating circuit
Operating clock source
Count clock source for Timers A/B
Operating clock source for LCD
Crystal oscillator
Xcin, Xcout
Available
Stopped
Note: Max. voltage is the same as VDC
Figure 1.11 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 1.12 shows some ex-
amples 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 1.11 and 1.12 vary with each oscil-
lator used. Use the values recommended by the manufacturer of your oscillator.
Microcomputer
(Built-in feedback resistor)
Xin
Xout
(Note)
Rd
Cin
Cout
Microcomputer
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. 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.
Fig. 1.11. Examples of main clock
1-21