低成本的SMD晶体ECS-160-18-5PXEN-TR是一款低损耗无铅的环保晶振

低成本的SMD晶体ECS-160-18-5PXEN-TR是一款低损耗无铅的环保晶振，负载电容是与晶体本身并联的外部电路电容的数量。在这个例子中，我们看到石英晶振晶体并联谐振模式总是高于串联谐振频率，并且以感抗为特征。在并联谐振振荡模式下，晶体的电感（动感）与振荡器的负载电容并联，从而形成一个 LC 谐振电路。该 LC 确定振荡器频率。

当指定一个串联谐振晶体时，负载电容可以忽略不计，因为晶体的运动电感和运动电容是唯一决定振荡频率的 LC 组件。

如果需要精确的频率控制，则需要精确的负载电容规格。为了演示，假设一个晶体单元被指定以 20MHz 的频率工作，容量为 20pF。假设随后将晶振单元放置在评估为 30pF 的电路中。

然后晶体单元的频率将低于指定值。相反，如果相关电路的评估值为 10pF，则频率将高于指定值。频率与负载电容之间的关系如图 6 所示。

ECS晶振发布ECS-160-18-5PXEN-TR，CSM-7X是低成本SMD晶振的绝佳选择。CSM-7X (5 px)最大外壳高度为4.3毫米。在电阻焊接金属包装中。较低的(5PLX)封装的型材封装高度为3.2 mm。
成本效益
低姿态
行业标准足迹
无铅/符合RoHS标准
Load capacitance is the amount of external circuit capacitance in parallel with the crystal itself. In this example we see that the crystals parallel resonance mode is always above the series resonance frequency and is characterized by inductive reactance. In parallel resonance oscillation mode, the crystal's inductance (motional inductance) is in parallel with the oscillator's load capacitance, thereby forming an LC tank circuit. This LC determines the oscillator frequency.

When specifying a series resonant crystal, load capacitance can be ignored since the crystal's motional inductance and motional capacitance are the only LC components that determines oscillation frequency.

For example, where CL1 and CL2 are the load capacitors and CSis the circuit stray capacitance, usually3pF ~ 5pF. It must be noted that changes in the value of the load capacitance will result in changes in the output frequency of the oscillator.

If exact frequency control is needed, then a precise specification of load capacitance is required. To demonstrate, presume that a crystal unit is specified to operate at a frequency of 20MHz with a capacity of 20pF. Assume that the crystal unit is then placed in a circuit which presents an assessment of 30pF.

The frequency of the crystal unit will then be lower than the specified value. Contrarily, should the circuit in question present an assessment of 10pF, the frequency will be higher than the specified value. The association between frequency and load capacitance is shown in Figure 6.