Holtek HT66F20-1 Manual page 49

HT66F20-1/HT66F30-1/HT68F20-1/HT68F30-1
Flash MCU with EEPROM
H i g h S p e e d
O s c i l l a t i o n
H X T
E R C
H I R C
H i g h S p e e d O s c i l l a t i o n
C o n f i g u r a t i o n O p t i o n
L o w S p e e d
O s c i l l a t i o n
L I R C
f
L X T
L o w S p e e d O s c i l l a t i o n
C o n f i g u r a t i o n O p t i o n
Note: When the system clock source f
stop to conserve the power. Thus there is no f
Together with f
SYS
is used as a source for the Time Base interrupt functions and for the TMs.
Rev. 1.40
f
H
6 - s t a g e P r e s c a l e r
f / 2
H
f / 4
H
f / 8
H
f / 1 6
H
f / 3 2
H
f / 6 4
H
L
System Clock Configurations
is switched to f
SYS
/4 it is also used as one of the clock sources for the Watchdog timer. The f
49
H L C L K ,
C K S 2 ~ C K S 0 b i t s
f
S U B
F a s t W a k e - u p f r o m S L E E P M o d e o r
I D L E M o d e C o n t r o l ( f o r H X T o n l y )
f
T B C
f
T B
f / 4
S Y S
T B C K
f
S U B
f
S
f / 4
S Y S
C o n f i g u r a t i o n O p t i o n
from f , the high speed oscillation will
L H
~f /64 for peripheral circuit to use.
H H
f
S Y S
T i m e B a s e
W D T
clock
TBC
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