upd78f0103hmca1-5a4-a Renesas Electronics Corporation., upd78f0103hmca1-5a4-a Datasheet - Page 94

• Manufacturer Part Number: upd78f0103hmca1-5a4-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

5.4.2 Internal oscillator
always oscillates the internal oscillation clock after RESET release (240 kHz (TYP.)).
5.4.3 Prescaler
speed system clock is selected as the clock to be supplied to the CPU.
5.5 Clock Generator Operation
mode.
enabling the following.
(1) Enhancement of security function
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An internal oscillator is incorporated in the 78K0/KB1+.
“Can be stopped by software” or “Cannot be stopped” can be selected by the option byte. The internal oscillator
The prescaler generates various clocks by dividing the high-speed system clock oscillator output when the high-
Caution When the internal oscillation clock is selected as the clock supplied to the CPU, the prescaler
The clock generator generates the following clocks and controls the operation modes of the CPU, such as standby
• High-speed system clock f
• Internal oscillation clock f
• CPU clock f
• Clock to peripheral hardware
The CPU starts operation when the internal oscillator starts outputting after reset release in the 78K0/KB1+, thus
When the high-speed system clock is set as the CPU clock by the default setting, the device cannot operate if the
high-speed system clock is damaged or badly connected and therefore does not operate after reset is released.
However, the start clock of the CPU is the internal oscillation clock, so the device can be started by the internal
oscillation clock after reset release by the clock monitor (detection of high-speed system clock stop).
Consequently, the system can be safely shut down by performing a minimum operation, such as acknowledging a
reset source by software or performing safety processing when there is a malfunction.
generates various clocks by dividing the internal oscillator output (f
CPU
R
XP
CHAPTER 5 CLOCK GENERATOR
User’s Manual U16846EJ3V0UD
X
= 240 kHz (TYP.)).