4570 Datasheet, PDF (35/69 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
4570 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
CLOCK CONTROL
The clock control circuit consists of the following circuits.
q Clock generating circuit
q Control circuit to stop the clock oscillation
q System clock selection circuit
q Instruction clock generating circuit
q Control circuit to return from the RAM back-up mode
XIN
XOUT
Oscillation
circuit
System clock
Frequency dividing
circuit
(divided by 4)
MR3
1
0
Internal clock
generating circuit
(devided by 3)
Insturuction clock
Counter
POF instruction
R
Q
S
Wait time control
circuit (Note)
Software
start signal
RESET
Key-on wakeup control register
K00,K01,K02,K03
Falling detected
Multi-
plexer
Port P40
Port P41
Port P42
Port P43
I12
“L” level
Ports P0, P1
0
P21/INT
1
“H” level
Note: The wait time control circuit is automatically used to generate the time required to stabilize the
f(XIN) oscillation.
Fig. 32 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. A feedback resistor is built-in between pins
XIN and XOUT.
ROM ORDERING METHOD
Please submit the information described below when ordering
Mask ROM.
(1) M34570M4-XXXFP Mask ROM Order Confirmation Form,
M34570M8-XXXFP Mask ROM Order Confirmation Form, or
M34570MD-XXXFP 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
CIN
M34570
Note: Externally connect a
damping resistor Rd
XOUT
depending on the
oscillation frequency.
(A feedback resistor is
built-in.)
Rd
Use the resonator
manufacturer’s
COUT
recommended value
because constants such
as capacitance depend
on the resonator.
Fig. 33 Ceramic resonator external circuit
34