ADM3095E-EP Enhanced Product
Rev. 0 | Page 12 of 14
THEORY OF OPERATION
RS-485 WITH ADDED DO-160G EMC ROBUSTNESS
The ADM3095E-EP is a 3.0 V to 5.5 V RS-485 transceiver with
added robustness that reduces system failures when operating
in harsh application environments, such as MILA avionics for
sensors, actuators, and engine control.
Lightning strikes to jet airliners are common—about once every
1000 flight hours. The DO-160G standard, Environmental
Conditions and Test Procedures for Airborne Equipment, is a
standard for the environmental testing of avionics hardware.
Many airplane manufacturers specify DO-160G, Section 22,
lightning induced transient susceptibility, as a requirement for
critical systems, like guidance, radars, communications, engine
controls, heat controls, and air controls. Aircraft radome, wing
tips, fin tips, nacelles, and landing gear are areas most likely to
be hit by lightning strikes.
The ADM3095E-EP integrates fully certified DO-160G EMC
protection on RS-485 bus pins, with Section 22 lightning
protection. The ADM3095E-EP also provides Section 25 ±15 kV
ESD air discharge protection. For Section 22 lightning, the
ADM3095E-EP provides protection against Waveform 3,
Waveform 4/Waveform 1, and Waveform 5A to Level 4 using
33 Ω or 47 Ω current limiting resistors to GND.
CERTIFIED DO-160G EMC PROTECTION
Table 6 details the open circuit voltage (V
OC
) and short-circuit
current (I
SC
) as specified in the DO-160G Section 22 lightning
transient susceptibility standard for Waveform 3, Waveform 4/
Waveform 1, and Waveform 5A for pin injection testing. The
peak currents for the DO-160G Level 4 tests are much greater
than the standard industrial surge IEC 61000-4-5 peak currents.
The waveform shape with rise and decay times for the DO-
160G standard are significantly longer than those specified by
the IEC 61000-4-5 standard, as shown in Figure 31. Due to the
high amounts of energy associated with the DO-160G Section
22 lightning standard, the ADM3095E-EP is tested using external
33 Ω or 47 Ω A pin and B pin bus current limiting resistors for
testing to GND. These resisters are required in addition to the
ADM3095E-EP integrated EMC protection circuitry.
0
100
200
300
400
500
600
700
800
0 20 40 60 80 100 120
CURRENT (A)
TIME (µs)
IEC 61000-4-5 SURGE
DO-160G SECTION 22
WAVEFORM 1
DO-160G SECTION 22
WAVEFORM 5A
15680-131
Figure 31. DO-160G Section 22 Waveform 1 and Waveform 5A, and IEC
61000-4-5 Surge Waveform
DO-160G ADM3095E-EP TEST DETAILS
Figure 32 and Figure 33 show the Waveform 3 test setup
coupling and decoupling network (CDN), the Waveform 5A, and
Waveform 4/Waveform 1 CDN. For testing to the RS-485 bus
side, GND, an additional 33 Ω or 47 Ω current limiting
resistance is added on the A and B bus pins. DO-160G Section 22
testing is performed on one pin at a time. The test is not
performed in common mode. Table 7 and Table 8 show a
summary of the ADM3095E-EP certified test results.
Table 6. DO-160G Section 22 Pin Injection Level 4 Compared to IEC 61000-4-5 Lightning Level 4
Level DO-160G Waveform 3 DO-160G Waveform 4/Waveform 1 DO-160G Waveform 5A IEC 61000-4-5
4 1500 V, 60 A 750 V, 150 A 750 V, 750 A 4000 V, 49 A
3 600 V, 24 A 300 V, 60 A 300 V, 300 A 2000 V, 24.5 A
Table 7. DO-160G Section 22 Pin Injection Level 4 Certified Test Results
Testing to
Current Limiting
Resistor
DO-160 Waveform 3;
1500 V, 60 A
DO-160 Waveform 4/
Waveform 1; 750 V, 150 A
DO-160 Waveform 5A;
750 V, 750 A
GND 47 Ω or 33 Ω Pass with 47 Ω Pass with 33 Ω Pass with 33 Ω
Table 8. DO-160G Section 22 Pin Injection Level 3 Certified Test Results
Testing to
Current Limiting
Resistor
DO-160 Waveform 3;
600 V, 24 A
DO-160 Waveform 4/
Waveform 1; 300 V, 60 A
DO-160 Waveform 5A;
300 V, 300 A
GND 33 Ω Pass Pass Pass
