To check an ESD simulator’s output, you must measure the waveform of the resulting current across a low-impedance, high-frequency resistive shunt connected to ground. The target mounts in the center of a 1.2-m2 ground plane and must have VSWR of less than 1.22 and an insertion loss of less than 0.3 dB up to 4 GHz.

IEC 61000-4-2 also specifies that you place the measurement oscilloscope inside a Faraday cage to shield it from the radiated ESD pulse. You will also need good-quality low-loss cables between the target, attenuators, and the oscilloscope. To comply with the IEC standards you should keep the total cable length less than 1 m, and a double-shielded cable that prevents signal leakage from affecting your measurement is strongly recommended.

EUT Test Setup

The direct discharge test simulates the human body model of electrostatic discharge and must be set up to recreate similar conditions. It is important to make sure that you have the proper grounding system in place before you begin testing. When using a table top for testing, you want to have a horizontal coupling plane on top of the table but below an insulation sheet. This should be connected to a ground reference plane on the floor using a 2 x 470kΩ bleed resistor cable as shown:

If the EUT is too large for a table top, place the EUT on an insulation pallet that is at least 0.1m in height. For the indirect contact discharge part of the test, a vertical coupling plane should be set up 10cm from the EUT, and also connected to the ground reference plane using the bleed resistors. Once set up, a power supply should be connected to the EUT and ESD gun. It is important to make sure that the room where the test is conducted is at a temperature of 15°C to 35°C and relative humidity is between 30% and 60%.

The test procedure is rather simple. For direct discharge, place the ESD gun to the point of test on the EUT, and discharge at 1 second intervals. This should be performed at least 10 times at both positive and negative polarities, and results recorded. For an indirect discharge test, the same process is repeated except that the discharge goes to the vertical or horizontal coupling plane, rather than directly to the EUT. Multiple discharge points may be required for testing, depending on the EUT.

The results are classified in 4 ways: