Crystal oscillator, also known as crystal oscillator, is an electronic component used to generate stable frequency signals.

  The connection methods of crystal oscillators are mainly divided into two types: internal crystal oscillators and external crystal oscillators. The main difference between these two connection methods lies in the connection method between the crystal oscillator and other components of the circuit board.

  1. Internal crystal oscillator:

  *Internal crystal oscillators are usually directly integrated into integrated circuits or modules.

  *As the crystal oscillator is already built-in, users do not need to make additional external connections.

  *This design approach simplifies the wiring and assembly process of circuit boards.

  *But if the user needs to replace the crystal oscillator or adjust its parameters, it may be more difficult because the entire integrated circuit or module may need to be replaced.

  2. External crystal oscillator:

  *External crystal oscillators require users to connect them to other components on the circuit board.

  1. Passive crystal oscillator:

  *Number of pins: Usually consisting of two pins, it is a type of non-polar device (some passive crystal oscillators have fixed pins without polarity).

  *Working principle: It is necessary to use an external clock circuit (usually connected to the oscillation circuit inside the main IC) to generate an oscillation signal (sine wave signal).

  *External components: Two external capacitors can fine tune the clock frequency generated by the crystal oscillator.

  2. Active crystal oscillator:

  *Number of pins: Generally, there are four pins.

  *Working principle: No internal oscillator of the CPU is required, as long as power is supplied, a clock signal can be generated and output as a square wave signal.

  *Features: Stable signal, good quality, simple connection method, smaller accuracy error than passive crystal oscillator, but more expensive.

  Regarding the connection method of crystal oscillators, it is generally necessary to pay attention to the following points:

  *Parallel resistance: can reduce the Q value of the crystal, making it easier for the crystal to vibrate. But the parallel resistance cannot be too small, otherwise it is not easy to vibrate at low temperatures.

  *Series resistor: can reduce the excitation power of the crystal, prevent damage, and limit the oscillation amplitude.

  *Load capacitance: Different crystal oscillators produced by different manufacturers with the same nominal frequency may require different load capacitance. Therefore, special attention should be paid when selecting and using.

  The equivalent circuit of a crystal oscillator can be seen as a series connected RLC circuit, where R is the ESR equivalent series resistance, L and C are the equivalent inductance and capacitance, respectively, and Cp is the parasitic capacitance. These components together determine the working performance and stability of the crystal oscillator.

  The connection and classification of crystal oscillators depend on their specific type and application scenario. In practical applications, it is necessary to choose the appropriate crystal oscillator type and connection method based on specific circuit design and working requirements. For more technical questions about crystal oscillators, please consult TROQ's original factory and we will provide you with free answers!

  *Usually, external crystal oscillators are connected to the circuit board through pins or soldering.

  *This connection method provides more flexibility as different types of crystal oscillators can be selected or replaced as needed.

  *But this also increases the complexity of circuit boards and the difficulty of assembly.

  In practical applications, the choice between an internal or external crystal oscillator mainly depends on specific application requirements and circuit design. For example, in some applications that require strict space requirements or high integration, internal crystal oscillators may be more preferred. In applications that require more flexibility and customization, external crystal oscillators may be more suitable.

  According to its working mode and structure, crystal oscillators can be mainly divided into two categories: passive crystal oscillators and active crystal oscillators.