adm489ar-reel7 Analog Devices, Inc., adm489ar-reel7 Datasheet - Page 12

• Manufacturer Part Number: adm489ar-reel7
• Description: Full-duplex, Low Power, Slew Rate Limited, Eia Rs-485 Transceivers
• Manufacturer: Analog Devices, Inc.

ADM488/ADM489
Table 8 shows the peak voltages for each of the environments.
Table 8. Peak Voltages
Level
1
2
3
4
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.
V
V
VOLTAGE
SOURCE
HIGH
Figure 25. IEC1000-4-4 Fast Transient Waveform
5ns
0.2/0.4ms
V
0.5
1
2
4
PEAK
R
C
C
C
(kV) PSU
300ms
Figure 26. EFT Generator
50ns
L
Z
S
R
M
16ms
C
V
0.25
0.5
1
2
D
PEAK
(kV) I/O
OUTPUT
50Ω
t
t
Rev. D | Page 12 of 16
Test results are classified according to the following:
•
•
•
•
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 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.
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.