HT48R50A-1/HT48C50-1
Application Circuits
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Note: The resistance and capacitance for reset circuit should be designed to ensure that the VDD is stable and re-
mains in a valid range of the operating voltage before bringing RES high.
²*² Make the length of the wiring, which is connected to the RES pin as short as possible, to avoid noise
interference.
The following table shows the C1, C2 and R1 values corresponding to the different crystal values. (For refer-
ence only)
Crystal or Resonator
4MHz Crystal
C1, C2
0pF
R1
10kW
12kW
10kW
10kW
10kW
27kW
9.1kW
10kW
10kW
4MHz Resonator
10pF
0pF
3.58MHz Crystal
3.58MHz Resonator
2MHz Crystal & Resonator
1MHz Crystal
25pF
25pF
35pF
300pF
300pF
300pF
480kHz Resonator
455kHz Resonator
429kHz Resonator
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.
Rev. 2.00
19
March 8, 2006
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
