upd78f0148m1gka1-9eu Renesas Electronics Corporation., upd78f0148m1gka1-9eu Datasheet - Page 143

• Manufacturer Part Number: upd78f0148m1gka1-9eu
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

6.5
mode.
enabling the following.
(1) Enhancement of security function
(2) Improvement of performance
The clock generator generates the following clocks and controls the operation modes of the CPU, such as standby
• X1 input clock f
• Internal oscillation clock f
• Subsystem 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/KF1, thus
When the X1 input clock is set as the CPU clock by the default setting, the device cannot operate if the X1 input
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 X1 input 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.
Because the CPU can be started without waiting for the X1 input clock oscillation stabilization time, the total
performance can be improved.
A timing diagram of the CPU default start using internal oscillator is shown in Figure 6-12.
Clock Generator Operation
CPU
XP
XT
R
CHAPTER 6 CLOCK GENERATOR
User’s Manual U15947EJ3V1UD
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