ADM206E/ADM207E/ADM208E/ADM211E/ADM213E

REV. B

–12–

Testing for immunity involves irradiating the device with an EM

field. There are various methods of achieving this including use

of anechoic chamber, stripline cell, TEM cell, GTEM cell. A

stripline cell consists of two parallel plates with an electric field

developed between them. The device under test is placed within

the cell and exposed to the electric field. There are three severity

levels having field strengths ranging from 1 V to 10 V/m. Results

are classified in a similar fashion to those for IEC1000-4-4.

1. Normal operation.

2. Temporary degradation or loss of function which is self-

recoverable when the interfering signal is removed.

3. Temporary degradation or loss of function which requires

operator intervention or system reset when the interfering

signal is removed.

4. Degradation or loss of function which is not recoverable due

to damage.

The ADM2xxE family of products easily meets Classification 1

at the most stringent (Level 3) requirement. In fact field strengths

up to 30 V/m showed no performance degradation and error-free

data transmission continued even during irradiation.

Table VII. Test Severity Levels (IEC1000-4-3)

Field Strength

Level

V/m

11

23

310

EMISSIONS/INTERFERENCE

EN55 022, CISPR22 defines the permitted limits of radiated

and conducted interference from Information Technology (IT)

equipment. The objective of the standard is to minimize the

level of emissions both conducted and radiated.

For ease of measurement and analysis, conducted emissions are

assumed to predominate below 30 MHz and radiated emissions

are assumed to predominate above 30 MHz.

CONDUCTED EMISSIONS

This is a measure of noise which gets conducted onto the line

power supply. Switching transients from the charge pump which

are 20 V in magnitude and containing significant energy can

lead to conducted emissions. Other sources of conducted emis-

sions can be due to overlap in switch on-times in the charge

pump voltage converter. In the voltage doubler shown below, if

S2 has not fully turned off before S4 turns on, this results in a

conducted emissions. It is therefore important that the switches

in the charge pump guarantee break-before-make switching

under all conditions so that instantaneous short circuit condi-

tions do not occur.

The ADM2xxE has been designed to minimize the switching

transients and ensure break-before-make switching thereby

minimizing conducted emissions. This has resulted in the level

of emissions being well below the limits required by the specifi-

cation. No additional filtering/decoupling other than the recom-

mended 0.1

µF capacitor is required.

Table VI.

V Peak (kV)

V Peak (kV)

Level

PSU

I-O

1

0.5

0.25

2

1

0.5

32

1

44

2

A simplified circuit diagram of the actual EFT generator is

illustrated in Figure 29.

The transients are coupled onto the signal lines using an EFT

coupling clamp. The clamp is 1 m long and it completely sur-

rounds the cable providing maximum coupling capacitance

(50 pF to 200 pF typ) between the clamp and the cable. High

energy transients are capacitively coupled onto the signal lines.

Fast rise times (5 ns) as specified by the standard result in very

effective coupling. This test is very severe since high voltages are

coupled onto the signal lines. The repetitive transients can often

cause problems where single pulses don’t. Destructive latch-up

may be induced due to the high energy content of the transients.

Note that this stress is applied while the interface products are

powered up and are transmitting data. The EFT test applies

hundreds of pulses with higher energy than ESD. Worst case

transient current on an I-O line can be as high as 40A.

Test results are classified according to the following:

1. Normal performance within specification limits.

2. Temporary degradation or loss of performance which is self-

recoverable.

3. Temporary degradation or loss of function or performance

which requires operator intervention or system reset.

4. Degradation or loss of function which is not recoverable due

to damage.

The ADM2xxE have been tested under worst case conditions

using unshielded cables and meet Classification 2. Data trans-

mission during the transient condition is corrupted but it may

be resumed immediately following the EFT event without user

intervention.

HIGH

VOLTAGE

SOURCE

L

50

OUTPUT

Figure 29. IEC1000-4-4 Fast Transient Generator

IEC1000-4-3 RADIATED IMMUNITY

IEC1000-4-3 (previously IEC801-3) describes the measurement

method and defines the levels of immunity to radiated electro-

magnetic fields. It was originally intended to simulate the elec-

tromagnetic fields generated by portable radio transceivers or

any other device which generates continuous wave radiated

electromagnetic energy. Its scope has since been broadened to

include spurious EM energy which can be radiated from fluores-

cent lights, thyristor drives, inductive loads, etc.