(ESR FOR SMD3225 CRYSTAL)

ESR (Equivalent Series Resistance) is the sum of in-phase AC resistance. It includes resistance of the dielectric, plate material, electrolytic solution, and terminal leads at a particular frequency. ESR acts like a resistor in series with a capacitor.

ESR（等效串联电阻） 是同相交流电阻的总和。它包括电介质、板材料、电解液和端子引线在特定频率下的电阻。ESR的作用类似于与电容器串联的电阻器。

The first thing to state is that this is not a measured parameter, it is a figure derived from the equivalent crystal circuit. However, the actual measured parameter of resonant resistance equates fairly well to it. The ESR of a crystal is the resistance exhibited at series resonance, it is proportional to the power dissipated within the crystal.

首先要声明的是，这不是一个测量参数，它是从等效晶体电路得出的数字。然而，谐振电阻的实际测量参数相当等同于ESR。晶体的ESR是串联谐振时表现出的电阻，它与晶体内耗散的功率成正比。

To put it simply it indicates the amount of power required by the crystal to resonate at it’s given frequency. The simple rule of thumb is, the bigger the piece of quartz the lower the ESR, which can be clearly seen if you compare the three sizes of crystal shown below.

简单地说，它表示晶体在其给定频率下共振所需的功率量。简单的经验法则是，石英晶片越大，ESR越低，如果您比较下面显示的三种尺寸的晶体，可以清楚地看到这一点。

以8MHz晶体为例：

SMD3225   ESR≤200Ω

SMD5032   ESR≤100Ω

SMD7050   ESR≤60Ω

Some of the more popular simple oscillator circuits can refuse to start oscillation if a crystal with a too high an ESR is employed or may not operate consistently in application, as the circuit has insufficient gain to drive the higher ESR crystals.

在一些振荡电路中，如果采用的晶体ESR过高，振荡电路可能会发生不稳定现象或根本无法起振,因为电路没有足够的增益来驱动更高ESR的晶体。