Crystal vibration types, specifications, parameters and so on, may you have a look at some crystals related introduction and information, but at the time of distinguish is easy to confuse or choose the wrong, so, today to tell you is that you don't understand the crystals it doesn't matter, but the purchase crystals have 4 must keep firmly in mind.
1, in view of the crystals MHZ, we need to know models (or volume) of crystals. If it is in the case of only clear volume, foot of crystals is also need to be aware of (commonly used patch crystals have two feet and four feet). At the same time also need to know crystal vibration load (PF) and accuracy (PPM).
2, 32.768 K for purchasing crystals, we need to control the precision of the crystals, model (or volume). If the model is patch crystals, don't need to ask a foot, only need to load and precision of the master crystals. Because the volume of the crystals can be seen from the model, the crystals are what surface encapsulation. In addition, the plug-in crystals in don't know what type of cases, specific to describe the shapes of the plugin crystals, common plug-in crystals have cylindrical shape, oval plug-in iron clad feet, have U.
3, in view of the active crystals, from the model need to determine whether for removing crystals or voltage controlled crystal oscillators. The abbreviation for removing oscillator TCXO, the abbreviation for vco VCXO, voltage-controlled removing the abbreviation of oscillator for VC - TCXO. The other is to know how to from the model to judge its volume, without having to look at the front of the letters, only need to study at the back of the figure. So you can know from the model crystal vibration parameters of everything, only need to provide crystal vibration load capacitance, another accuracy PPM. Voltage size.
4, on the market commonly used SMT packaging: 2520322 5503 2603 5705. Above, encapsulated in know the frequency of cases, if the crystals are two foot patch crystals, we need to know is the ceramic surface encapsulation or metal surface encapsulation. Two foot patch crystals ceramic surface encapsulation of the specifications of the commonly used 5032 patch crystals, SMD crystals, 6035 if crystals are four foot patch crystals, will pay special attention to, because the four foot patch crystals is likely to be passive crystals may be active crystals. Other active crystals is divided into removing oscillator, voltage-controlled oscillator, voltage-controlled removing oscillator.
