ASM202E/ASM±±8±A
Table 4. IEC1000-4-2 Compliance Levels
A simplified circuit diagram of the actual EFT generator is
illustrated in Figure 22.
Level
Contact Discharge
Air Discharge
2 kV
4 kV
8 kV
15 kV
1
2
3
4
2 kV
4 kV
6 kV
8 kV
The transients are coupled onto the signal lines using an EFT
coupling clamp. The clamp, which is 1 m long, completely
surrounds the cable, providing maximum coupling capacitance
(50 pF to 200 pF typ) between the clamp and the cable. High
energy transients are capacitively coupled to the signal lines.
Fast rise times (5 ns), as specified by the standard, result in very
effective coupling. This test is very strenuous because high voltages
are coupled onto the signal lines. The repetitive transients often
cause problems where 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
hundreds of pulses with higher energy than ESD. Worst-case
transient current on an I/O line can be as high as 40 A.
Table 5. ADM202E/ADM1181A ESD Test Results
ESD Test Method
MIL-STD-883B
IEC1000-4-2
Contact
I/O Pins
±15 kV
±8 kV
Air
±15 kV
FAST TRANSIENT/BURST TESTING (IEC1000-4-4)
IEC1000-4-4 (previously 801-4) covers electrical fast transient
(EFT)/burst immunity. Electrical fast transients occur as a result
of arcing contacts in switches and relays. The tests simulate 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
appearing on the line, therefore, consists of a burst of extremely
fast transient impulses. A similar effect occurs when switching
on fluorescent lights.
C
D
R
R
M
HIGH
VOLTAGE
SOURCE
L
C
50Ω
OUTPUT
Z
C
S
C
Figure 22. IEC1000-4-4 Fast Transient Generator
Test results are classified according to the following:
•
•
•
Classification 1: Normal performance within specifi-
cation limits
The fast transient/burst test defined in IEC1000-4-4 simulates
this arcing, and its waveform is illustrated in Figure 17. It
consists 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.
Classification 2: Temporary degradation or loss of
performance that is self-recoverable
Classification 3: Temporary degradation or loss of function
or performance that requires operator intervention or
system reset
V
•
Classification 4: Degradation or loss of function that is not
recoverable due to damage
t
300ms
15ms
The ADM202E/ADM1181A meet Classification 2 and have
been tested under worst-case conditions using unshielded
cables. Data transmission during the transient condition is
corrupted, but can resume immediately following the EFT event
without user intervention.
5ns
V
50ns
t
0.2/0.4ms
Figure 21. IEC1000-4-4 Fast Transient Waveform
Rev. C | Page 11 of 16
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