4280 Datasheet, PDF (21/48 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTERS

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
XIN
XOUT
OSC
POF instruction
R
Q
S
CCK instruction
Frequency
divider
(divided by 8)
Multi-
plexer
Internal clock
generating circuit
(divided by 4)
INSTCK
STCK
Internal power-on reset circuit
Pull-down control
register PU0
Port D7
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.
A feedback resistor is built-in between XIN pin and XOUT pin.
ROM ORDERING METHOD
Please submit the information described below when ordering
Mask ROM.
(1) Mask ROM Order Confirmation Form................................. 1
(2) Data to be written into mask ROM .......................... EPROM
(three sets containing the identical data)
(3) Mark Specification Form .................................................... 1
XIN
4
CIN
4280
XOUT
5
Use the resonator
manufacturer’s
recommended value
because constants
such as capacitance
depend on the
resonator.
COUT
Fig. 25 Ceramic resonator external circuit
20