A New Circuit Approach to Predict Discharge Curents for Air Discharges of ESD Generators

Abstract. To predict discharge current waveforms for air discharges of electrostatic discharge (ESD) generators (ESD-guns) used in an IEC immunity test against human ESD, an equivalent circuit modelling for air discharges of ESD-guns is proposed. To simulate spark discharges, two typical spark resistance formulae (Rompe-Weizel’s and Toepler’s) are applied to the modelling, which consists of a spark voltage source derived from a spark resistance formula, the output impedance of an ESD-gun, and an injecting-point impedance of equipment under test (EUT). For validation, discharge current waveforms for air discharges onto an IEC calibration target in lieu of EUT are calculated to compare with measured waveforms. As a result, it is found that the calculated discharge current waveforms derived from both spark resistance formulae approximately agree with the measured ones, and that Rompe-Weuzel’s and Toepler’s formulae can better predict their rising slopes and tails, respectively.