HT66F25D View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
MFG CO.
'HT66F25D' PDF : 177 Pages View PDF
A/D Flash Type 8-bit MCU with EEPROM
HT66F24D/HT66F25D
C1
3 2 .7 6 8
kH z
C2
XT1
Rp
XT2
In te r n a l
O s c illa to r
C ir c u it
In te rn a l R C
O s c illa to r
T o in te r n a l
c ir c u its
N o te : 1 . R p , C 1 a n d C 2 a r e r e q u ir e d .
2 . A lth o u g h n o t s h o w n p in s h a v e a
p a r a s itic c a p a c ita n c e o f a r o u n d 7 p F .
External LXT Oscillator
LXT Oscillator C1 and C2 Values
Crystal Frequency
C1
C2
32.768kHz
10pF
10pF
Note:1. C1 and C2 values are for guidance only.
2. RP=5M~10MΩ is recommended.
32.768kHz Crystal Recommended Capacitor Values
LXT Oscillator Low Power Function
The LXT oscillator can function in one of two modes, the Quick Start Mode and the Low Power
Mode. The mode selection is executed using the LXTLP bit in the TBC register.
LXTLP Bit
0
1
LXT Mode
Quick Start
Low-power
After power on, the LXTLP bit will be automatically cleared to zero ensuring that the LXT oscillator
is in the Quick Start operating mode. In the Quick Start Mode the LXT oscillator will power up
and stabilise quickly. However, after the LXT oscillator has fully powered up it can be placed
into the Low-power mode by setting the LXTLP bit high. The oscillator will continue to run but
with reduced current consumption, as the higher current consumption is only required during the
LXT oscillator start-up. In power sensitive applications, such as battery applications, where power
consumption must be kept to a minimum, it is therefore recommended that the application program
sets the LXTLP bit high about 2 seconds after power-on.
It should be noted that no matter what condition the LXTLP bit is set to, the LXT oscillator will
always function normally, the only difference is that it will take more time to start up if in the Low-
power mode.
Supplementary Oscillator
The low speed oscillator, in addition to providing a system clock source, is also used to provide a
clock source to the Time Base Interrupts function.
Rev. 1.10
39
March 25, 2013
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