4583 Datasheet, PDF (70/153 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4583 Group
PRELIMINARY
Notice: This is not a final specification.
Some parametric limits are subject to change.
23 _{Clock control}
Execute the main clock (f(XIN)) selection instruction (CMCK,
CRCK or CYCK instruction) in the initial setting routine of pro-
gram (executing it in address 0 in page 0 is recommended).
The oscillation circuit by the CMCK, CRCK or CYCK instruction
can be selected only at once. The oscillation circuit correspond-
ing to the first executed one of these instructions is valid.
The CMCK, CRCK, and CYCK instructions can be used only to
select main clock (f(XIN)). In this time, the start of oscillation and
the switch of system clock are not performed.
When the CMCK, CRCK, and CYCK instructions are never ex-
ecuted, main clock (f(XIN)) cannot be used and system can be
operated only by on-chip oscillator.
The no operated clock source (f(RING)) or (f(XIN)) cannot be
used for the system clock. Also, the clock source (f(RING) or
f(XIN)) selected for the system clock cannot be stopped.
27 _{Note on Power Source Voltage}
When the power source voltage value of a microcomputer is less
than the value which is indicated as the recommended operating
conditions, the microcomputer does not operate normally and
may perform unstable operation.
In a system where the power source voltage drops slowly when
the power source voltage drops or the power supply is turned off,
reset a microcomputer when the supply voltage is less than the
recommended operating conditions and design a system not to
cause errors to the system by this unstable operation.
24 _{On-chip oscillator}
The clock frequency of the on-chip oscillator depends on the sup-
ply voltage and the operation temperature range.
Be careful that variable frequencies when designing application
products.
When considering the oscillation stabilize wait time at the switch
of clock, be careful that the variable frequency of the on-chip os-
cillator clock.
25 External clock
When the external clock signal for the main clock (f(XIN)) is used,
connect the clock source to XIN pin and XOUT pin open. In pro-
gram, after the CMCK instruction is executed, set main clock
(f(XIN)) oscillation start to be enabled (MR1=0).
For this product, when RAM back-up mode and main clock
(f(XIN)) stop (MR1=1), XIN pin is fixed to “H” in order to avoid the
through current by floating of internal logic. The XIN pin is fixed to
“H” until main clock (f(XIN)) oscillation start to be valid (MR1=0)
by the CMCK instruction from reset state. Accordingly, when an
external clock is used, connect a 1 kΩ or more resistor to XIN pin
in series to limit of current by competitive signal.
26 Electric Characteristic Differences Between Mask ROM and One
Time PROM Version MCU
There are differences in electric characteristics, operation mar-
gin, noise immunity, and noise radiation between Mask ROM and
One Time PROM version MCUs due to the difference in the
manufacturing processes.
When manufacturing an application system with the One time
PROM version and then switching to use of the Mask ROM ver-
sion, please perform sufficient evaluations for the commercial
samples of the Mask ROM version.
Rev.3.00 Aug 06, 2004 page 70 of 151
REJ03B0009-0300Z