what is a problem should be taking care of while choosing a replacement for the crystal oscillator
When choosing a replacement for a crystal oscillator, there are several key factors to consider to ensure that the replacement meets the required specifications and operates reliably:
1.Frequency ： Make sure that the replacement crystal oscillator has the correct frequency . The frequency of the replacement crystal oscillator should match the original crystal oscillator as closely as possible.
2.Frequency stability: The frequency stability of the replacement oscillator should be at least as good as that of the original crystal oscillator. Especially original oscillator has special requirement .Frequency stability refers to the ability of the oscillator to maintain a constant frequency over time and with changes in temperature and other environmental factors.
3.Output waveform: The commonly used output modes of crystal oscillators mainly include: TTL, CMOS, ECL, PECL, LVDS, Sine Wave . The output waveform of the replacement oscillator should be compatible with the circuit that it is driving. Most crystal oscillators produce a sine wave, but some applications may require a different type of waveform.
4.Package size and pinout: The replacement oscillator should have the same package size and pinout as the original crystal oscillator. This is important to ensure that the replacement can be easily installed in the existing circuit. Common crystal oscillator packages are generally divided into two types, plug-in crystal oscillator (DIP) and chip crystal oscillator (SMD).
DIP series :
Cylindrical crystal package size (mm): 2*6/3*8
UM-1 crystal package size (mm): 7.8*3.2*6.9
HC-49S crystal package size (mm): 10.5*3.5*3.8
HC-49U crystal package size (mm): 11.05*4.65.13.46
HC-49SMD crystal package size (mm): 13*4.8*4
SMD series ：
SMD1612 package size (mm): 1.6*1.2
SMD2016 package size (mm): 2.0*1.6
SMD2520 package size (mm): 2.5*2.0
SMD3225 package size (mm): 3.2*2.5
SMD5032 package size (mm): 5.0*3.2
SMD6035 package size (mm): 6.0*3.5
SMD7050 package size (mm): 7.0*5.0
5.Supply voltage and current: The general input voltage value is 1.8V, 2.8V, 3.3V, 5V .Make sure that the replacement oscillator operates within the same supply voltage and current range as the original crystal oscillator.
6.Aging and reliability: The replacement oscillator should have a similar aging and reliability performance as the original crystal oscillator. Industrial aging of gold plating can reach ±1ppm in crystal units . standard aging is ±3ppm .Aging refers to the gradual change in frequency over time, and reliability refers to the ability of the oscillator to operate continuously without failure.
7.Environmental factors: Consider the environmental factors in which the replacement oscillator will be used. For example, if the oscillator will be used in a high-temperature environment, like -40~125℃,make sure that the replacement oscillator is rated for high-temperature operation.
By taking these factors into account, you can choose a replacement crystal oscillator that will provide reliable and accurate timing for your application.