4250 Datasheet, PDF (30/59 Pages) Energizer – Industrial Rubber Light

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
MITSUBISHI MICROCOMPUTERS
4250 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
XIN
XOUT
Oscillation
circuit
Internal clock
generating circuit
(divided by 4)
Instruction clock
Counter
POF instruction
R
Q
S
Wait time control
circuit (Note)
Software
start signal
RESET
Key-on wakeup control register
K00, K01
Multiplexer
Ports G1–G3
Ports S0–S3
Rising detected
K02 _Rising
0
1
Falling
G0/INT pin
Note: The wait time control circuit is used to start the microcomputer operation after 3584 to 3585 machine cycles
for the time required to stabilize the f(XIN) oscillation.
Fig. 27 Clock control circuit structure
Clock signal f(XIN) is obtained by connecting XIN pin and XOUT
pin directly, and externally connecting a resistor to XIN and a
capacitor to XOUT. Connect this external circuit to pins XIN and
XOUT at the shortest distance.
When an external clock signal is input, note the input waveform
(refer to the list of precaution).
ROM ORDERING METHOD
Please submit the information described below when ordering
Mask ROM.
(1) M34250M2-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
XOUT
The system clock frequency
is affected by a capacitor, a
resistor and an LSI, So, set
the constants within the
range of the frequency limits.
Fig. 28 Resistor and capacitor external circuit
29