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
transient current glitch between V
CC
and GND which results in
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
321
442
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.
R
C
R
M
C
C
HIGH
VOLTAGE
SOURCE
L
Z
S
C
D
50V
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.
