UG-1116 EVAL-ADM3095EEPBZ User Guide
Rev. 0 | Page 4 of 8
TERMINATION AND PULL-UP/PULL-DOWN
RESISTORS
The E VA L-ADM3095EEPBZ includes the R1 footprint for
fitting a termination resistor between the A and B driver
outputs and receiver inputs. By default, the 120 Ω resistor (R1)
between Pin A and Pin B, shown in Figure 6, is not on the
EVA L-ADM3095EEPBZ. Remove this resistor if the EVA L -
ADM3095EEPBZ connects to a bus that already terminates at
both ends. For more information about proper termination,
see the AN-960 Application Note, RS-485/RS-422 Circuit
Implementation Guide.
Although the ADM3095E-EP has a built-in receiver fail-safe for
the bus idle condition, there are footprints on the EVA L-
ADM3095EEPBZ for fitting the R6 pull-up resistor to V
CC
on
Pin A, as well as the R2 pull-down resistor to GND on Pin B.
When connecting to other devices that require such external
biasing resistors on the bus, these resistors can be fitted. The exact
value required for a 200 mV minimum differential voltage in the
bus idle condition depends on the V
CC
supply voltage (for example,
960 Ω for 3.3 V and 1440 Ω for 5 V).
For more information about the bus idle fail-safe, see the AN-960
Application Note, RS-485/RS-422 Circuit Implementation Guide.
DECOUPLING AND RESERVOIR CAPACITORS
The E VA L-ADM3095EEPBZ uses the following decoupling and
reservoir capacitors:
• C2 and C6 are 100 nF ceramic capacitors fitted between V
CC
(
Pin 2) and GND (Pin 1), and between V
IO
(Pin 3) and GND
(Pin 1), respectively. Pads for additional capacitors (C1 and
C8) are unpopulated when the printed circuit board (PCB) is
assembled.
• Additional 10 µF tantalum capacitors (C3 and C7) are
added for the power supply inputs at the J1 connector.
ROBUST DO-160G EMC RS-485 EVALUATION
BOARD
The E VA L-ADM3095EEPBZ evaluation board has been lab
tested and certified to provide RS-485 A and RS-485 B bus pin
protection for the following DO-160G standards and test levels.
For more information, see Table 2, Table 3, and Table 4.
• Protection against Section 22, Waveform 3 to Level 4
(1500 V, 6 0 A) using 47 Ω current limiting resistors on the
A and B bus pins.
• Protection against Section 22, Waveform 4/Waveform 1 t
o
L
evel 4 (750 V, 150 A) using 33 Ω current limiting resistor
s
on the A and B bus pins.
• Protection against Section 22, Waveform 5A to Level 4
(750 V, 7 5 0 A) using 33 Ω current limiting resistors on the
A and B bus pins.
The E VA L-ADM3095EEPBZ also provides protection against
the following:
• Section 25 ESD to ±15 kV air discharge.
• Human body model (HBM) ESD to >±30 kV.
CERTIFIED DO-160G EMC PROTECTION
Table 2 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/
Wave form 1, and Waveform 5A for pin injection testing. The
peak currents for the DO-160G Level 4 tests are much greater
than standard industrial surge IEC 61000-4-5 peak currents.
The waveform shape and rise/decay times for the DO-160G
standard are significantly longer than those specified by the
IEC 61000-4-5 standard, as shown in Figure 3. Due to the high
amounts of energy associated with the DO-160G, Section 22
lightning standard, the ADM3095E-EP was tested using external
33 Ω or 47 Ω A pin and B pin bus current limiting resistors for
testing to GND. These resisters were 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
15649-003
F
igure 3. DO-160G Section 22 Waveform 1 and Waveform 5A, and
IEC61000-4-5 Surge Waveform
DO-160G ADM3095E-EP TEST DETAILS
Figure 4 and Figure 5 show the Waveform 3 test setup coupling/
decoupling network (CDN) and the Waveform 5A, Waveform 4/
Wave form 1 CDN, respectively. For testing to RS-485 bus side,
GND, an additional 33 Ω or 47 Ω current limiting resistance is
added on both 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 3 shows a summary of the ADM3095E-EP
certified test results.
