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Crystal oscillators are a type of frequency components that are widely used in electronic products, such as monitoring equipment, mobile phones, vacuum cleaners, smart wearables, and other products. The crystal oscillators we often see are plug-in crystal oscillators and chip crystal oscillators.
Crystal oscillators are usually divided into two types: passive crystal oscillators and active crystal oscillators. Passive crystal oscillators have two pins, and active crystal oscillators have four pins. However, passive crystal oscillators also have four pins. What is the difference between a four-pin passive crystal oscillator and a four-pin active crystal oscillator? Do you know?
· Distinguish between passive and active crystal oscillators by pins
1. Two-pin crystal oscillators must be passive crystal oscillators, regardless of whether they are plug-in crystal oscillators or chip crystal oscillators
2. Passive crystal oscillators are thinner than active crystal oscillators;
3. Four-pin chip crystal oscillators need to be carefully distinguished. Active crystal oscillators can be distinguished by the printing on the lower left pin (PIN1 pin) with a dot. On the contrary, if there is no dot on the lower left pin, it is a passive crystal oscillator;
4. Chip crystal oscillators with more than four pins must be active crystal oscillators;
5. Check the ground terminal of the multimeter to see if there are two pins connected on the opposite side.
Taking Yangxing passive crystal oscillator, YSX321SL series as an example, the following is the size and pin diagram:
The chip passive crystal oscillator has no direction in the case of four pins. Pins 1 and 3 are functional pins, responsible for frequency input and frequency output. The other pins 2 and 4 are grounded or suspended. Grounding enhances the welding and fixing of the crystal oscillator on the circuit board, assists in heat dissipation, and meets circuit design specifications.
The connection principle of the four-pin passive chip crystal oscillator circuit: the current flows in from the crystal oscillator pin 1 and flows out from pin 3, or the current can also flow in from pin 3 and flow out from pin 1. Because pins 1 and 3 are non-polar pins and have no directionality, there is no need to worry about sticking it upside down.
Taking Yangxing active crystal oscillator, YSO110TR series as an example, the following is the size and pin diagram:
The active crystal oscillator pin identification has a marked point at the end of the 1st pin, and then counterclockwise 1, 2, 3, 4 are distributed in this way.
The common usage of four-pin active crystal oscillator:
1st pin is suspended, 2nd pin is grounded, 3rd pin is connected to output, 4th pin is connected to voltage, and there is a dot at the 1st pin position as a mark.
