Do you really understand the characteristics and key parameters of TVS diodes? Ha ha, today Xiaobian to tage electronic technology characteristics and key parameters for you on the next TVS diode. Because most of the engineers don‘t know it. Read the text:
1.1 TVS diode characteristics
Under the condition of the reverse application, the TVS diode is in a high impedance state to the protected circuit. When the voltage exceeds the breakdown voltage, the TVS diode will provide a low impedance path, and shunt diode TVS through high current to flow is the instantaneous current protection components, while the voltage protection components at both ends of the clamping voltage limit in TVS diode. When the overvoltage condition disappears, the TVS diode returns to the high impedance state. Key parameters of 1.2 TVS diodes
(1) the minimum breakdown voltage VBR: the device in the breakdown of the region, in the specified test current IBR (general case IBR = 1mA), the measured voltage at both ends of the device is called the minimum breakdown voltage.
(2) DC reverse off state voltage VRWM:TVS diode maximum continuous or pulsed voltage, the voltage applied to TVS diode between the poles, it is reverse off state, the current flowing through it should be less than or equal to the maximum reverse leakage current IR.
(3) pulse peak current IPP: when the reverse operation, in the specified pulse waveform (such as: 10/1000 s double exponential waveform), the device allows the maximum surge current.
(4) the maximum clamping voltage VC: when the pulse peak current flowing through the IPP TVS diode, the maximum voltage appears across the value called clamp voltage VC. VC and IPP reflect the surge suppression capability of TVS diodes. Usually the VC and VBR is called the clamping factor (coefficient), its value is generally at 1.2 ~ 1.4.
(5): PPP pulse peak power pulse peak power PPP is a product of pulse peak current IPP and maximum clamp voltage VC, PPP = IPP * VC. It is the maximum peak power of TVS diode. In a given maximum clamp voltage, pulse peak power of PPP is higher, the surge current capacity is greater.
(6) junction capacitance CJ:TVS diode junction capacitance CJ is determined by the avalanche junction cross section and the bias voltage of the silicon wafer. The size of the CJ is directly proportional to the current carrying capacity of the TVS diode, and the CJ is too large to attenuate the signal. Therefore, the capacitance CJ is an important parameter of the data interface circuit using TVS diode. In the protection of high frequency signal lines, the main purpose is to use the low junction capacitance of the TVS tube, the general low junction capacitance of the TVS tube of the junction capacitance can be zero to a few P F order of magnitude.