ADM488/ADM489

Rev. D | Page 12 of 16

300ms

16ms

V

t

V

0.2/0.4ms

t

5ns

50ns

Figure 25. IEC1000-4-4 Fast Transient Waveform

Table 8 shows the peak voltages for each of the environments.

Table 8. Peak Voltages

Level

VPEAK (kV) PSU

VPEAK (kV) I/O

1

0.5

0.25

2

1

0.5

3

2

1

4

4

2

A simplified circuit diagram of the actual EFT generator is

shown in Figure 26.

These transients are coupled onto the signal lines using an EFT

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

rounds the cable, providing maximum coupling capacitance

(50 pF to 200 pF typical) 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 because high voltages

are coupled onto the signal lines. The repetitive transients often

cause problems, while single pulses do not. Destructive latch-up

can 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 transmitting data. The EFT test applies hun-

dreds of pulses with higher energy than ESD. Worst-case

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

RC

CC

ZS

L

RM CD

HIGH

VOLTAGE

SOURCE

50Ω

OUTPUT

Figure 26. EFT Generator

Test results are classified according to the following:

•

Normal performance within specification limits.

•

Temporary degradation or loss of performance that is self-

recoverable.

•

Temporary degradation or loss of function or performance

that requires operator intervention or system reset.

•

Degradation or loss of function that is not recoverable due

to damage.

The ADM488/ADM489 have been tested under worst-case

conditions using unshielded cables, and meet Classification 2 at

Severity Level 4. Data transmission during the transient

condition is corrupted, but it can be resumed immediately

following the EFT event without user intervention.

RADIATED IMMUNITY (IEC1000-4-3)

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

electromagnetic fields generated by portable radio transceivers

or any other device that generates continuous wave-radiated

electromagnetic energy. Its scope has been broadened to include

spurious EM energy, which can be radiated from fluorescent

lights, thyristor drives, inductive loads, and so on.

Testing for immunity involves irradiating the device with an

EM field. Test methods include the use of anechoic chamber,

stripline cell, TEM cell, and GTEM cell. These consist of two

parallel plates with an electric field developed between them.

The device under test is placed between the plates and exposed

to the electric field. The three severity levels have field strengths

ranging from 1 V/m to 10 V/m. Results are classified as follows:

•

Normal operation.

•

Temporary degradation or loss of function that is self-

recoverable when the interfering signal is removed.

•

Temporary degradation or loss of function that requires

operator intervention or system reset when the interfering

signal is removed.

•

Degradation or loss of function that is not recoverable due

to damage.