ADM3311E

–9–

REV. A

D1

D2

Tx

TRANSMITTER

OUTPUT

Figure 21b. Transmitter Output Protection Scheme

ESD TESTING (IEC1000-4-2)

IEC1000-4-2 (previously 801-2) specifies compliance testing

using two coupling methods, contact discharge and air-gap

discharge. Contact discharge calls for a direct connection to the

unit being tested. Air-gap discharge uses a higher test voltage

but does not make direct contact with the unit under test. With

air discharge, the discharge gun is moved toward the unit under

test, developing an arc across the air gap, hence the term air

discharge. This method is influenced by humidity, temperature,

barometric pressure, distance and rate of closure of the discharge

gun. The contact-discharge method, while less realistic, is more

repeatable and is gaining acceptance in preference to the air-gap

method.

Although very little energy is contained within an ESD pulse,

the extremely fast rise time coupled with high voltages can cause

failures in unprotected semiconductors. Catastrophic destruc-

tion can occur immediately as a result of arcing or heating. Even

if catastrophic failure does not occur immediately, the device

may suffer from parametric degradation, which may result in

degraded performance. The cumulative effects of continuous

exposure can eventually lead to complete failure.

I-O lines are particularly vulnerable to ESD damage. Simply

touching or plugging in an I-O cable can result in a static dis-

charge that can damage or completely destroy the interface

product connected to the I-O port. Traditional ESD test meth-

ods such as the MIL-STD-883B method 3015.7 do not fully

test a product’s susceptibility to this type of discharge. This test

was intended to test a product’s susceptibility to ESD damage

during handling. Each pin is tested with respect to all other

pins. There are some important differences between the tradi-

tional test and the IEC test:

(a) The IEC test is much more stringent in terms of discharge

energy. The peak current injected is over four times greater.

(b) The current rise time is significantly faster in the IEC test.

(c) The IEC test is carried out while power is applied to the device.

It is possible that the ESD discharge could induce latch-up in the

device under test. This test is therefore more representative of a

real-world I-O discharge where the equipment is operating nor-

mally with power applied. For maximum peace of mind however,

both tests should be performed, thus ensuring maximum protec-

tion both during handling and later, during field service.

R1

R2

C1

DEVICE

UNDER TEST

HIGH

VOLTAGE

GENERATOR

ESD TEST METHOD

R2

C1

H. BODY MIL-STD883B

1.5k

100pF

IEC1000-4-2

330

150pF

Figure 22. ESD Test Standards

100

90

36.8

10.0

TIME t

Figure 23. Human Body Model ESD Current Waveform

100

90

10

TIME t

30ns

60ns

0.1 TO 1ns

Figure 24. IEC1000-4-2 ESD Current Waveform

The ADM3311E is tested using both of the above-mentioned

test methods. All pins are tested with respect to all other pins as

per the MIL-STD-883B specification. In addition, all I-O pins

are tested as per the IEC test specification. The products were

tested under the following conditions:

(a) Power-On—Normal Operation

(b) Power-Off

Four levels of compliance are defined by IEC1000-4-2. The

ADM3311E meets the most stringent compliance level for con-

tact discharge. This means that the products are able to with-

stand contact discharges in excess of 8 kV.

Table II. IEC1000-4-2 Compliance Levels

Contact Discharge

Air Discharge

Level

(kV)

(kV)

12

2

24

4

36

8

48

15

Table III. ADM3311E ESD Test Results

ESD Test Method

I-O Pins (kV)

Other Pins (kV)

MIL-STD-883B

±15

±3

IEC1000-4-2

Contact

±8