UPD78F0890GK(A)-GAJ-AX NEC, UPD78F0890GK(A)-GAJ-AX Datasheet - Page 160

• 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

6.6.9 Conditions before clock oscillation is stopped
conditions before the clock oscillation is stopped.
160
Internal high-speed
oscillation clock
X1 clock
External main system clock
XT1 clock
External subsystem clock
Remarks 1. The number of clocks listed in Table 6-7 is the number of main system clocks before switchover.
Caution When switching the internal high-speed oscillation clock to the high-speed system clock, bit 2
The following lists the register flag settings for stopping the clock oscillation (disabling external clock input) and
Clock
(XSEL) of MCM must be set to 1 in advance. The value of XSEL can be changed only once after a
reset release.
2. Calculate the number of clocks in Table 6-7 by removing the decimal portion.
Set Value Before Switchover
Table 6-8. Conditions Before the Clock Oscillation Is Stopped and Flag Settings
Example When switching the main system clock from the internal high-speed oscillation clock to the
Table 6-7. Maximum Time Required for Main System Clock Switchover
MCM0
0
1
high-speed system clock (@ oscillation with f
MCS = 1 or CLS = 1
(The CPU is operating on a clock other than the internal high-speed
oscillation clock)
MCS = 0 or CLS = 1
(The CPU is operating on a clock other than the high-speed system clock)
CLS = 0
(The CPU is operating on a clock other than the subsystem clock)
1 + 2f
RH
/f
XH
Conditions Before Clock Oscillation Is Stopped
= 1 + 2 × 8/10 = 1 + 2 × 0.8 = 1 + 1.6 = 2.6 → 2 clocks
CHAPTER 6 CLOCK GENERATOR
1 + 2f
User’s Manual U17554EJ4V0UD
(External Clock Input Disabled)
XH
/f
RH
clock
0
Set Value After Switchover
MCM0
RH
= 8 MHz, f
1 + 2f
RH
/f
XH
XH
clock
= 10 MHz)
1
RSTOP = 1
MSTOP = 1
OSCSELS = 0
Flag Settings of SFR
Register