1. Introduction of crystal oscillator.
The function of crystal oscillator is to produce the original clock frequency. The crystal oscillator frequency is doubled by the frequency generator and becomes a variety of clock frequencies in the computer. It is sent to each device on the main board to make the equipment work normally.
2. Crystal oscillator code.
The crystal oscillator is represented by the letter X or Y. For example, X 2 represents the second crystal oscillator on the motherboard.
3. Crystal oscillator circuit symbol.
The symbols used in circuit diagrams are shown in figure 1.
4. Crystal oscillator common model.
32.768kHz crystal oscillator is used to provide reference frequency for RTC (Real Time Clock) circuit in Nanqiao chip. If the 32.768kHz crystal vibration damage will result in no boot, no reset, no running code and so on, the failure will not be the same in different motherboards. The 14.318MHz crystal oscillator is used to generate the reference frequency of the clock chip, which causes the whole board to have no clock signal when damaged. The 25MHz crystal oscillator is used to provide the reference frequency for the network card and some South Bridge chips. The three common crystal oscillations on the motherboard are shown in figure 2.
5. The quality of crystal oscillation is judged.
The results are as follows:
(1) using oscilloscope to measure the waveform and frequency of crystal oscillator, the frequency is the same and the difference is bad. (2) the method of substitution is used to judge the quality of crystal oscillator. 6. Crystal oscillator application circuit.
For example, the principle of crystal oscillator is shown in figure 3. Intel-NH82801GB Nanqiao chip is supplied with VCCRTC real time clock power supply and RTCRST# real time clock reset, and 32.768kHz crystal oscillator is supplied with 32.768kHz frequency from crystal oscillator to real time clock circuit of south bridge chip. Let the real-time clock circuit work to save CMOS settings (e.g. time, date, startup item, etc.).