Clock Generating Circuit
Unde
deeopmen
Mitsubishi microcomputers
M30201 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
18
Figure 1.16. Examples of sub-clock
Table 1.3. Main clock and sub-clock generating circuits
Clock Generating Circuit
The clock generating circuit contains two oscillator circuits that supply the operating clock sources to the
CPU and internal peripheral units.
Example of oscillator circuit
Figure 1.15 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 1.16 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 15 and 16 vary with each oscillator used. Use the values
recommended by the manufacturer of your oscillator.
Figure 1.15. Examples of main clock
Main clock generating circuit
CPU’s operating clock source
Internal peripheral units’
operating clock source
Ceramic or crystal oscillator
X
IN
, X
OUT
Available
Oscillating
Externally derived clock can be input
Sub clock generating circuit
CPU’s operating clock source
Timer A/B/X’s count clock
source
Crystal oscillator
X
CIN
, X
COUT
Available
Stopped
Use of clock
Usable oscillator
Pins to connect oscillator
Oscillation stop/restart function
Oscillator status immediately after reset
Other
M30201
(Built-in feedback resistor)
X
IN
X
OUT
Open
Externally derived clock
Vcc
Vss
M30201
(Built-in feedback resistor)
X
IN
X
OUT
R
d
C
IN
C
OUT
(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 X
IN
and X
OUT
following the
instruction.
M30201
(Built-in feedback resistor)
X
CIN
X
COUT
Open
Externally derived clock
Vcc
Vss
M30201
(Built-in feedback resistor)
X
CIN
X
COUT
(Note)
R
Cd
C
CIN
C
COUT
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
X
CIN
and X
COUT
following the
instruction.