CHAPTER 5 CLOCK GENERATORS
Preliminary User’s Manual U16898EJ1V0UD
73
(a) The internal reset signal is generated by the power-on clear function on power application, the option byte is
referenced after reset, and the system clock is selected.
(b) The option byte is referenced and the system clock is selected. Then the high-speed Ring-OSC clock
operates as the system clock.
Figure 5-11. Status Transition of Default Start by High-Speed Ring-OSC
HALT
instruction
STOP
instruction
V
DD
> 2.1 V
±
0.1 V
Start with PCC = 02H,
PPCC = 02H
HALT
STOP
Interrupt
Reset signal
Interrupt
Power
application
Reset by
power-on clear
High-speed Ring-OSC
selected by option byte
Clock division ratio
variable during
CPU operation
Remark PCC:
Processor clock control register
PPCC: Preprocessor clock control register
(2) Crystal/ceramic oscillator
If crystal/ceramic oscillation is selected by the option byte, a clock frequency of 500 kHz to 10 MHz can be
selected and the accuracy of processing is improved because the frequency deviation is small, as compared with
high-speed Ring-OSC oscillation (8 MHz (TYP.)).
Figures 5-12 and 5-13 show the timing chart and status transition diagram of default start by the crystal/ceramic
oscillator.
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