upd78f9211grt2-jjg-a ETC-unknow, upd78f9211grt2-jjg-a Datasheet - Page 73

• Manufacturer Part Number: upd78f9211grt2-jjg-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: ETC-unknow

5.5
oscillators.
OPTION BYTE.
(1) High-speed internal oscillator
A clock (f
• High-speed internal oscillator:
• Crystal/ceramic oscillator:
• External clock input circuit:
The system clock oscillator is selected by the option byte. For details of the option byte, refer to CHAPTER 15
Note Operation stop time is 277
When the high-speed internal oscillation is selected by the option byte, the following is possible.
• Shortening of start time
• Improvement of expandability
Figures 5-8 and 5-9 show the timing chart and status transition diagram of the default start by the high-speed
internal oscillation.
Remark When the high-speed internal oscillation is used, the clock accuracy is ±5%.
Operation of CPU Clock Generator
If the high-speed internal oscillator is selected as the oscillator, the CPU can be started without having to wait
for the oscillation stabilization time of the system clock. Therefore, the start time can be shortened.
If the high-speed internal oscillator is selected as the oscillator, the X1 and X2 pins can be used as I/O port
pins. For details, refer to CHAPTER 4 PORT FUNCTIONS.
System clock
Internal reset
CPU
CPU clock
) is supplied to the CPU from the system clock (f
RESET
Figure 5-8. Timing Chart of Default Start by High-Speed Internal Oscillation
V
DD
H
(a)
µ
s (MIN.), 544
System clock is selected.
Internally oscillates a clock of 8 MHz (TYP.).
Oscillates a clock of 1 MHz to 10 MHz.
Supplies a clock of 1 MHz to 10 MHz to X1 pin.
(Operation stops
CHAPTER 5 CLOCK GENERATORS
Option byte is read.
User’s Manual U16994EJ3V0UD
µ
Note
s (TYP.), and 1.075 ms (MAX.).
)
(b)
X
) oscillated by one of the following three types of
High-speed internal oscillation clock
PCC = 02H, PPCC = 02H
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