HT48CU80 Holtek Semiconductor, HT48CU80 Datasheet - Page 34

• Manufacturer Part Number: HT48CU80
• Description: (HT48RU80 / HT48CU80) I/O Type 8-Bit MCU
• Manufacturer: Holtek Semiconductor

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Application Circuits
Note: The resistance and capacitance for reset circuit should be designed to ensure that the VDD is stable and re-
Rev. 1.00
mains in a valid range of the operating voltage before bringing RES high.
interference.
The following table shows the C1, C2 and R1 values corresponding to the different crystal values. (For refer-
ence only)
* Make the length of the wiring, which is connected to the RES pin as short as possible, to avoid noise
4MHz Crystal
4MHz Resonator
3.58MHz Crystal
3.58MHz Resonator
2MHz Crystal & Resonator
1MHz Crystal
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.
Crystal or Resonator
34
C1, C2
300pF
300pF
300pF
10pF
25pF
25pF
35pF
0pF
0pF
HT48RU80/HT48CU80
9.1k
10k
12k
10k
10k
10k
27k
10k
10k
R1
April 12, 2006