Realgiant Crystal Oscillator- -The Heart of Digital Circuit

We usually say that the crystal resonator is actually by cutting equipment will be cultured were obtained by cutting thin crystal, crystal growth with artificial culture environment, currently on the market the better quality of the Russian growth of crystal.The reason that the crystal is a digital circuit in the heart, because all digital circuits require a stable clock signal, the most common is to use the crystal to solve, can be said as long as there is a digital circuit where you can see the crystal.

We often say that the crystal resonator contains two kinds, a need to add the drive circuit to produce the frequency signal, this kind of crystal called crystal resonators, such as the common 49S package, SMD3225 package of 5032 feet, a four SMD package. Without a driving circuit, only need to add the signal voltage to produce frequency this signal, called crystal oscillator, basically is the 4 pin package contains power pins, pin, frequency output pin.

How to Select the main parameters of the crystal?

Here we focus on the crystal resonator. The main parameters of general crystal, core frequency, temperature, precision, equivalent series impedance, capacitance, package and so on.

The core of crystal frequency, selection of core frequency depends on the requirements of frequency requirement components, such as clock chip to 32.768KHz crystal, MCU is generally a range, basically from 4 megabytes to tens of megabytes there.

The work of crystal temperature, the temperature of a separate, mainly due to the crystal is a physical device, the temperature and the price is proportional to the temperature requirements are higher, the higher the price, so the choice of crystal also needs to focus on working temperature.

The crystal precision value, accuracy of common 0.5ppm, 5ppm +, 10ppm +, 20ppm +, 0,5ppm + 50ppm and so on. The current domestic only through digital compensation can do abroad have high precision in 3225 or even 2016. The accuracy of the selection to the reference frequency requirements of precision devices as the clock chip with high precision. In general. Within 5ppm, the ordinary applications are chosen in + 20ppm.

Crystal equivalent series impedance, the main parameters are related to the driving ability, that is to say a relationship with the drive current. The equivalent resistance to small driving current is small. The ability to adapt to the external drive circuit is higher.

Matching capacitor crystal, by changing the matching capacitance parameter values, the core frequency can change the crystal, that is to say, by matching the capacitance adjustment crystal to do fine tune the accuracy. The main way to do this is the current domestic high precision temperature compensated crystal oscillator.

Package form crystal, current encapsulated crystal is diverse, the user needs to choose according to their actual situation, is based mainly on board space, processing methods, and cost considerations.

The common attention of the crystal

In general, the crystal is a key component of a system. The stability of the crystal is directly related to the whole system. The need to pay attention to the following points.

The following two aspects related to the machining process, a reflow temperature, the crystal is a physical device, the high temperature might affect the crystal frequency when crossing the reflow, deviate from the core frequency, when the use level of K crystal needs special attention. An ultrasonic cleaning cleaning process in, this is mainly the ultrasonic frequency if the fall in the working frequency of the crystal resonance may be caused by crystal oscillator, LED chip break, crystal internal adverse.

Need to pay attention to the application of crystal is usually made in a stable state, there are many crystal failure situations are long-term work in the drive or crystal is under actuated state, this can look through the crystal output pin waveform can be analyzed. A driver may lead to crystal is not up to the normal life, underactuated may lead to weaken the crystal system anti-interference ability, often for no reason lost the clock.

The anti-jamming design of the crystal oscillator is a small signal, because the device is vulnerable to external interference, resulting in system clock problems. This mainly from two aspects, one is the layout clock signal processing, is used to package processing. One is on board the other frequency this device, it needs to be isolated between different frequencies.For more crystal information please contact the Realgiant crystal website.

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