UPD78F0890GK(A)-GAJ-AX NEC, UPD78F0890GK(A)-GAJ-AX Datasheet - Page 141

• Manufacturer Part Number: UPD78F0890GK(A)-GAJ-AX
• Description: 8BIT MCU, 128K FLASH, 7K RAM, LQFP
• Manufacturer: NEC

Specifications of UPD78F0890GK(A)-GAJ-AX

• Controller Family/series: UPD78F
• No. Of I/o's: 55
• Ram Memory Size: 7KB
• Cpu Speed: 20MHz
• No. Of Timers: 10
• No. Of Pwm: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 128KB
• Oscillator Type: External, Internal

6.5 Clock Generator Operation
mode.
the 78K0/FE2, thus 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
• Main system clock f
• Subsystem clock f
• Internal low-speed oscillation clock f
• CPU clock f
• Peripheral hardware clock f
The CPU starts operation when the on-chip internal high-speed oscillator starts outputting after a reset release in
When the X1 clock is set as the CPU clock by the default setting, the device cannot operate if the X1 clock is
damaged or badly connected and therefore does not operate after reset is released. However, the start clock of
the CPU is the on-chip internal high-speed oscillation clock, so the device can be started by the internal high-
speed oscillation clock after a reset release. 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 clock oscillation stabilization time, the total
performance can be improved.
A timing diagram of the CPU default start using the internal high-speed oscillation clock is shown in Figure 6-12
and 6-13.
• High-speed system clock f
• Internal high-speed oscillation clock f
• XT1 clock f
• External subsystem clock f
X1 clock f
External main system clock f
CPU
X
XT
SUB
XP
PRS
XH
EXCLKS
EXCLK
CHAPTER 6 CLOCK GENERATOR
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