Impedance Dependencies of TVS Diode’s Response Against ESD Stress

The protection performance of an electrostatic-discharge (ESD) protection device may differ from one device to another, even if the specifications are equivalent. Additionally, the performance of an ESD-protection device changes when implemented in different circuit impedances or external connection device. Therefore, this study aims to clear the influence of circuit impedances on the performance of ESD-protection devices. First, we measured the response voltage waveform under five different resistances using three types of TVS diode with the same breakdown voltage specification. Second, we analyzed the clamping duration and the time constant of the voltage drop after the clamping operation. We compared these characteristics among the three types of TVS diode. The results showed that the clamping duration and the time constant would be longer under a higher circuit impedance. The difference among TVS diodes will be more distinct as the impedance increases, even when the breakdown voltage specifications of the TVS diode are equivalent.