Materials & Test Equipment

• Oscilloscope (at least 2 GHz Analog Bandwidth)
• Coaxial Current Target Chain
• 20 dB attenuator (for 16kV ESD Simulators)
• 30 dB attenuator (for 30kV ESD Simulators)
• 4' x 4' Vertical Calibration Plane for ESD Target
• Tripod for ESD Simulator Gun
• Optional Faraday Cage for discharge isolation

ESD Waveshape Requirements

Following parameters to be considered when verifying the pulse shape from the ESD generator with an oscilloscope:

• First Peak Current
• Rise Time (0.6 to 1.0 ns)
• Current at 30 ns
• Current at 60 ns

Procedure

An oscilloscope must use 0% and Max thresholds in order to perform the EMC-specific measurement.

Capturing the correct waveform with the scope can only be achieved with the proper settings of the DSO. The settings need to be made to measure pulses with +/-2kV, +/-4kV, +/-6kV and +/-8kV. Four parameters need to be measured at each voltage level:
- Initial peak current
- Rise time between 10% and 90% of the initial peak
- Current value at 30ns
- Current value at 60ns

The time domain for the initial peak and rise time measurement is recommended to be set to 1ns/Div. For the current measurement at 30nS and 60ns a setting of 10ns/Div is recommended as being appropriate.

1. Capture a Single Pulse
2. Measure one pulse, verify rise time for positive pulses, verify fall time for negative pulses 
3. 1 GHz, 2 GHz, or 3GHz+ scope depending on standard specification

Calculating Ratio

Calculated from the impedance and attenuation values the following equation gives the proper ratio:

Ip = 5 x Vm

where
Vm is the voltage signal measured by the DSO in Volt
V1 is the voltage measured accros the CTR 2 target
Ip is the discharge current

Therefore
V1 = 20dB x Vm = 2ohm x Ip
Ip = 20dB x Vm/2ohm

For example:
A discharge current of 7.5A will give a voltage reading of 1.5V on the DSO.

Related Information

• ESD Simulator Gun Calibration Services
• IEC 61000-4-2: Test Standard for Electrostatic Discharge Immunity

Calibration Diagram

Using an oscilloscope and attenuators - verify the waveform coming off your ESD gun:

Note: Attenuator A should be 20 dB, Attenuator B (typically 10 dB) may not be required.