MITSUBISHI MICROCOMPUTERS
4280 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS
CLOCK CONTROL
The clock control circuit consists of the following circuits.
• System clock generating circuit
• Control circuit to stop the clock oscillation
• Control circuit to return from the RAM back-up state
CCK instruction
Frequency
divider
(divided by 8)
XIN
XOUT
OSC
Internal clock
generating circuit
(divided by 4)
Multi-
plexer
INSTCK
STCK
Internal power-on reset circuit
POF instruction
R
S
Q
Port D7
Pull-down control
register PU0
Ports E0, E1
Ports E2, G0–G3
Fig. 24 Clock control circuit structure
Clock signal f(XIN) is obtained by externally connecting a ceramic
resonator. Connect this external circuit to pins XIN and XOUT at
the shortest distance as shown Figure 26.
4280
Use the resonator
manufacturer’s
recommended value
because constants
such as capacitance
depend on the
A feedback resistor is built-in between XIN pin and XOUT pin.
X
IN
X
OUT
4
5
ROM ORDERING METHOD
Please submit the information described below when ordering
resonator.
Mask ROM.
(1) Mask ROM Order Confirmation Form.................................1
(2) Data to be written into mask ROM.......................... EPROM
(three sets containing the identical data)
C
IN
COUT
(3) Mark Specification Form .................................................... 1
Fig. 25 Ceramic resonator external circuit
MITSUBISHI
ELECTRIC
20
MITSUBISHI [ Mitsubishi Group ]
