HT49RV7 Datasheet, PDF (31/48 Pages) Holtek Semiconductor Inc – A/D With VFD Type 8-Bit MCU

HT49RV7/HT49CV7
The following table shows the C1, C2 and R1 values corresponding to the different crystal values. (For refer-
ence only)
Crystal or Resonator
C1, C2
R1
4MHz Crystal
0pF
10kW
4MHz Resonator
10pF
12kW
3.58MHz Crystal
0pF
10kW
3.58MHz Resonator
25pF
10kW
2MHz Crystal & Resonator
25pF
10kW
1MHz Crystal
35pF
27kW
480kHz Resonator
300pF
9.1kW
455kHz Resonator
300pF
10kW
429kHz Resonator
300pF
10kW
The function of the resistor R1 is to ensure that the oscillator will switch off should low voltage conditions
occur. Such a low voltage, as mentioned here, is one which is less than the lowest value of the MCU oper-
ating voltage. Note however that if the LVR is enabled then R1 can be removed.
Rev. 1.00
31
April 20, 2006