ADM3311 AD [Analog Devices], ADM3311 Datasheet - Page 10

• Manufacturer Part Number: ADM3311
• Manufacturer: AD [Analog Devices]

ADM3311E
FAST TRANSIENT BURST TESTING (IEC1000-4-4)
IEC1000-4-4 (previously 801-4) covers electrical fast-transient/
burst (EFT) immunity. Electrical fast transients occur as a
result of arcing contacts in switches and relays. The tests simu-
late the interference generated when, for example, a power relay
disconnects an inductive load. A spark is generated due to the
well known back EMF effect. In fact, the spark consists of a
burst of sparks as the relay contacts separate. The voltage appear-
ing on the line, therefore, consists of a burst of extremely fast
transient impulses. A similar effect occurs when switching on
fluorescent lights.
The fast transient burst test defined in IEC1000-4-4 simulates
this arcing and its waveform is illustrated in Figure 25. It con-
sists of a burst of 2.5 kHz to 5 kHz transients repeating at
300 ms intervals. It is specified for both power and data lines.
Level
1
2
3
4
A simplified circuit diagram of the actual EFT generator is
illustrated in Figure 26.
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 transmitting data. The EFT test applies hun-
dreds of pulses with higher energy than ESD. Worst case tran-
sient current on an I-O line can be as high as 40 A.
V
V
5ns
0.2/0.4ms
300ms
V Peak (kV)
PSU
0.5
1
2
4
Table IV.
50ns
15ms
V Peak (kV)
I-O
0.25
0.5
1
2
t
t
Test results are classified according to the following:
1. Normal performance within specification limits.
2. Temporary degradation or loss of performance, which is self-
3. Temporary degradation or loss of function or performance,
4. Degradation or loss of function that is not recoverable due to
The ADM3311E has 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.
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 that 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.
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-
3. Temporary degradation or loss of function that requires
4. Degradation or loss of function that is not recoverable due to
The ADM3311E easily meets Classification 1 at the most strin-
gent (Level 3) requirement. In fact, field strengths up to 30 V/m
showed no performance degradation and error-free data trans-
mission continued even during irradiation.
recoverable.
which requires operator intervention or system reset.
damage.
recoverable when the interfering signal is removed.
operator intervention or system reset when the interfering
signal is removed.
damage.
VOLTAGE
SOURCE
HIGH
R
C
C
C
L
Z
S
R
M
C
D
50
OUTPUT