HT46R22 The resistance and capacitance for reset circuit should be designed in such a way as to ensure that the VDD is Application Circuit

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HT46R22 circuit
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Holtek Semiconductor Inc.

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HT46R22 circuit
HT46R22 HT46C22
Application Circuits
V
D D
0 .0 1
m
F *
1 0 0 k
W
0 .1
m
F
1 0 k
W
V D D
R E S
P A 0 ~ P A 2
P A 3 /P F D
V
P A 4 /T M R
P A 5 /IN T
P A 6 /S D A
R
P A 7 /S C L
P B 0 /A N 0
P B 7 /A N 7
~
C 1
D D
4 7 0 p F
O S C
O S C 1
f
S
Y S
R C S y s te m O s c illa to r
3 0 k
W
< R
O S C
< 7 5 0 k
W
0 .1
m
F *
V S S
/4
O S C 2
O S C 1
C ry s ta l S y s te m
F o r th e v a lu e s ,
s e e ta b le b e lo w
O s c illa to r
O S C
C ir c u it
S e e R ig h t S id e
O S C 1
O S C 2
P C 0 ~ P C 1
P D 0 /P W M
C 2
R 1
O S C 2
O S C C ir c u it
H T 4 6 R 2 2 /H T 4 6 C 2 2
The following table shows the C1, C2 and R1 values corresponding to the different crystal values. (For reference only)
Crystal or Resonator
4MHz Crystal
3.58MHz Crystal
3.58MHz Resonator
2MHz Crystal & Resonator
1MHz Crystal
480kHz Resonator
455kHz Resonator
429kHz Resonator
C1, C2
0pF
10pF
0pF
25pF
25pF
35pF
300pF
300pF
300pF
R1
10kW
12kW
10kW
10kW
10kW
27kW
9.1kW
10kW
10kW
The function of the Resistor R1 is to ensure that the Oscillator will switch off should low voltage condi-
tions occur. Such a low voltage, as mentioned here, is one which is less than the lowest value of the
MCU operating voltage. Note however that if the LVR is enabled then R1 can be removed.
Note:
The resistance and capacitance for reset circuit should be designed in such a way as to ensure that the VDD is
stable and remains within a valid operating voltage range before bringing RES to high.
²*²
Make the length of the wiring, which is connected to the RES pin as short as possible, to avoid noise
interference.
Rev. 2.00
27
November 23, 2005