HT48R066G View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
MFG CO.
'HT48R066G' PDF : 126 Pages View PDF
HT48R064G/065G/066G/0662G
Enhanced I/O Type 8-Bit OTP MCU with OPA
External Crystal/Resonator Oscillator - HXT
The simple connection of a crystal across OSC1 and OSC2 will create the necessary phase shift and
feedback for oscillation. However, for some crystals and most resonator types, to ensure oscillation
and accurate frequency generation, it is necessary to add two small value external capacitors, C1 and
C2. The exact values of C1 and C2 should be selected in consultation with the crystal or resonator
manufacturer¢s specification.
C1
O SC1
In te r n a l
O s c illa to r
C ir c u it
Rp
Rf
T o in te r n a l
C2
O SC2
c ir c u its
N o te : 1 . R p is n o r m a lly n o t r e q u ir e d . 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 O S C 1 /O S C 2 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 .
Crystal/Resonator Oscillator - HXT
Crystal Oscillator C1 and C2 Values
Crystal Frequency
C1
C2
12MHz
¾
¾
8MHz
¾
¾
4MHz
1MHz
¾
100pF
¾
100pF
Note: C1 and C2 values are for guidance only.
Crystal Recommended Capacitor Values
External RC Oscillator - ERC
Using the ERC oscillator only requires that a resistor, with a value between 24kW and 1.5MW, is
connected between OSC1 and VDD, and a capacitor is connected between OSC and ground,
providing a low cost oscillator configuration. It is only the external resistor that determines the
oscillation frequency; the external capacitor has no influence over the frequency and is connected for
stability purposes only. Device trimming during the manufacturing process and the inclusion of
internal frequency compensation circuits are used to ensure that the influence of the power supply
voltage, temperature and process variations on the oscillation frequency are minimised. Here only the
OSC1 pin is used, which is shared with I/O pin PA6, leaving pin PA5 free for use as a normal I/O pin.
V DD
R O SC
470pF
P A 6 /O S C 1
P A 5 /O S C 2
External RC Oscillator - ERC
Rev. 1.10
38
October 23, 2012
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