Risks of ESD

AN3960

6/21

Doc ID 022082 Rev 1

2.1

Simulation and testing of electronic devices using models

Several models describe how to simulate an ESD stress. The schematic circuit of Figure 1,

shows how to generate an ESD event to a device under test (DUT). It is the basis of these

models.

Figure 1.

Electrostatic discharge test (ESD generator and DUT)

1.

2.

The charge and discharge switches are not closed simultaneously.

2.1.1

Human body model (HBM)

For testing the susceptibility of electronic devices to ESD stress from human contact, an

ESD simulator with a special output circuit called the human body model (HBM) is often

used.

This model simulates the discharge which might occur when a human touches an electronic

device (either a system or a component).

The HBM consists of a capacitor in series with a resistor (see Figure 1). The capacitor is

charged to a specified voltage from an external source, and then suddenly discharged

through the resistor into an electronic terminal of the DUT.

2.1.2

Machine model (MM)

This model simulates what happens when a machine becomes electrostatically charged

and subsequently discharges into an electronic device when it comes in contact with it.

The MM test circuit consists of charging up a 200 pF capacitor to a certain voltage and then

discharging this capacitor directly into the DUT.