Human Body Model

Figure 6 shows the Human Body Model and Figure 7

shows the current waveform it generates when dis-

charged into a low impedance. This model consists of

a 100pF capacitor charged to the ESD voltage of inter-

est, which is then discharged into the device through a

1.5k

Ω resistor.

IEC 1000-4-2

Since January 1996, all equipment manufactured

and/or sold in the European Union has been required to

meet the stringent IEC 1000-4-2 specification. The IEC

1000-4-2 standard covers ESD testing and perfor-

mance of finished equipment; it does not specifically

refer to integrated circuits. The MAX4843–MAX4846

help users design equipment that meets Level 3 of IEC

1000-4-2, without additional ESD-protection compo-

nents.

The main difference between tests done using the

Human Body Model and IEC 1000-4-2 is higher peak

current in IEC 1000-4-2. Because series resistance is

lower in the IEC 1000-4-2 ESD test model (Figure 8),

the ESD withstand voltage measured to this standard is

generally lower than that measured using the Human

Body Model. Figure 9 shows the current waveform for

the ±8kV IEC 1000-4-2 Level 4 ESD Contact Discharge

test. The Air-Gap test involves approaching the device

with a charger probe. The Contact Discharge method

connects the probe to the device before the probe is

energized.

Overvoltage Protection Controllers with

Low Standby Current

8

_______________________________________________________________________________________

CHARGE-CURRENT-

LIMIT RESISTOR

DISCHARGE

RESISTANCE

STORAGE

CAPACITOR

Cs

100pF

1M

Ω

1.5

Ω

HIGH-

VOLTAGE

DC

SOURCE

DEVICE

UNDER

TEST

Figure 6. Human Body ESD Test Model

90%

36.8%

TIME

CURRENT WAVEFORM

PEAK-TO-PEAK RINGING

(NOT DRAWN TO SCALE)

Ir

10%

0

0

AMPERES

Figure 7. Human Body Model Current Waveform

CHARGE-CURRENT-

LIMIT RESISTOR

DISCHARGE

RESISTANCE

STORAGE

CAPACITOR

Cs

150pF

50

Ω to 100Ω

330

Ω

HIGH-

VOLTAGE

DC

SOURCE

DEVICE

UNDER

TEST

Figure 8. IEC 1000-4-2 ESD Test Model

100%

90%

60ns

10%

tr = 0.7ns to 1ns

I

30ns

t

Figure 9. IEC 1000-4-2 ESD Generator Current Waveform