Evaluation Board User Guide
UG-317
One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
Evaluation Board for the
ADM2682E/ADM2687E
5 kV rms Signal and
Power Isolated RS-485 Transceivers with ±15 kV ESD Protection
FEATURES
5 kV rms power and signal isolated RS-485/RS-422 transceiver
Convenient connections for power and signal through screw
terminal blocks
Configurable as half duplex or full duplex
5 V or 3.3 V operation
Easily configurable through jumper connections
Test points for measuring all signals
Layout optimized for emissions according to the
AN-0971
Application Note
The evaluation board is easily configured through jumper
connections. The board can be used in half-duplex or full-
duplex configurations and has a 120 Ω termination resistor
fitted on the receiver input. The evaluation board can be used
with either the
ADM2682E
16 Mbps part or the
ADM2687E
500 kbps part. The driver and receiver are enabled and disabled
by jumper connections. Test points are included on the power
and signal lines on both sides of the isolation barrier.
RADIATED EMISSIONS
The
ADM2682E/ADM2687E
evaluation board is designed to
reduce emissions generated by the high frequency switching
elements used by the
isoPower®
technology to transfer power
through its transformer. The layout of the evaluation board
was generated using the guidelines provided in the
AN-0971
Application Note,
Recommendations for Control of Radiated
Emissions with
isoPower
Devices.
EVALUATION KIT CONTENTS
EVAL-ADM2682EEBZ or EVAL-ADM2687EEBZ
GENERAL DESCRIPTION
The
ADM2682E/ADM2687E
evaluation board can be used for
easy evaluation of the
ADM2682E
and
ADM2687E
power and
signal isolated RS-485 transceivers. Screw terminal blocks provide
convenient connections for the power and signal connections.
EVALUATION BOARD
Figure 1.
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.
Rev. 0 | Page 1 of 12
10174-001
UG-317
TABLE OF CONTENTS
Features .............................................................................................. 1
Evaluation Kit Contents ................................................................... 1
General Description ......................................................................... 1
Radiated Emissions .......................................................................... 1
Evaluation Board .............................................................................. 1
Revision History ............................................................................... 2
Evaluation Board Hardware Configuration .................................. 3
Test Setup ....................................................................................... 3
Jumper Settings ............................................................................. 3
Evaluation Board User Guide
Termination and Pull-Up/Pull-Down Resistors .......................4
Decoupling and Reservoir Capacitors ........................................4
Board Internal Layer Thickness ..................................................4
Evaluation Board Schematics...........................................................5
Assembly Drawings and Board Layout ..........................................6
Ordering Information .......................................................................9
Bill of Materials ..............................................................................9
Related Links ..................................................................................9
REVISION HISTORY
10/11—Revision 0: Initial Version
Rev. 0 | Page 2 of 12
Evaluation Board User Guide
EVALUATION BOARD HARDWARE CONFIGURATION
TEST SETUP
The
ADM2682E/ADM2687E
evaluation board is shown
in Figure 2 with the default jumper settings on LK1 through
LK4 (driver and receiver enabled), power connection on J1,
input signal connection on J2, and probes attached to RXD,
TXD, Y, and Z for a loopback test (LK5 and LK6 are closed
to connect A to Y and B to Z).
UG-317
JUMPER SETTINGS
The inputs to the
ADM2682E/ADM2687E
can be configured
using the jumpers on the evaluation board (see Table 1). Note
that multiple jumper blocks should not be placed on LK1 to
LK4 because the input sources may be shorted together. For
each link, a single jumper block can be moved from one posi-
tion to another, as specified in Table 1.
SIGNAL
GENERATOR
3.3V OR 5V
POWER
SUPPLY
OSCILLOSCOPE
J1
GND1
J3
RXD
RXD
LK1
A
B
VCC
RXD
RE
DE
TXD
GND2
A
B
Z
Y
VISO
LK6
LK5
A
B
Z
Y
SHIELD
J4
10174-010
EVAL-ADM2682E_87EEBZ
DE
TXD
TXD
J2
Figure 2. Basic Operation of the Evaluation Board for the
ADM2682E/ADM2687E
Isolated RS-485 Transceivers
Table 1. Jumper Configuration
Link
LK1
LK2
Connection
A
B
A
B
C
D
Description
Connects the receiver output (RxD) of the
ADM2682E/ADM2687E
to the J3 connector.
Connects the receiver output (RxD) of the
ADM2682E/ADM2687E
to the J8-1 terminal block connector.
Connects the receiver enable input (RE) of the
ADM2682E
/
ADM2687E
to V
CC
. This setting disables the receiver.
Connects the receiver enable input (RE) of the
ADM2682E
/
ADM2687E
to GND
1
. This setting enables the receiver.
Connects the receiver enable input (RE) of the
ADM2682E
/
ADM2687E
to the J8-2 terminal block connector.
Connects the receiver enable input (RE) of the
ADM2682E
/
ADM2687E
to the driver enable input (DE); that is, the
input for both RE and DE is set by LK3. This setting ensures that when the driver is enabled, the receiver is
disabled, or when the driver is disabled, the receiver is enabled.
Connects the driver enable input (DE) of the
ADM2682E/ADM2687E
to V
CC
. This setting enables the driver.
Connects the driver enable input (DE) of the
ADM2682E/ADM2687E
to GND
1
. This setting disables the driver.
Connects the driver enable input (DE) of the
ADM2682E/ADM2687E
to the J8-3 terminal block connector.
Connects the driver input (TxD) of the
ADM2682E/ADM2687E
to the J8-4 terminal block connector.
Connects the driver input (TxD) of the
ADM2682E/ADM2687E
to the J2 connector.
Connects the
ADM2682E/ADM2687E
Receiver Input A to Driver Output Y. When LK5 and LK6 are both connected,
the evaluation board is configured for half-duplex operation.
When LK5 and LK6 are both open, the evaluation board is configured for full-duplex operation.
Connects the
ADM2682E/ADM2687E
Receiver Input B to Driver Output Z. When LK5 and LK6 are both connected,
the evaluation board is configured for half-duplex operation.
When LK5 and LK6 are both open, the evaluation board is configured for full-duplex operation.
LK3
LK4
LK5
A
B
C
A
B
Closed
Open
Closed
Open
LK6
J8
RE
LK2 A
B
C
D
LK3
A
B
C
LK4
A
B
Rev. 0 | Page 3 of 12
UG-317
TERMINATION AND PULL-UP/PULL-DOWN
RESISTORS
The evaluation board includes the RT and RT1 footprints for
fitting termination resistors between the A and B receiver inputs
and the Y and Z driver outputs. By default, the board is fitted
with a 120 Ω resistor, RT, between A and B. This resistor should
be removed if the board is connected to a bus that is already
terminated at both ends. For more information about proper
termination, see the
AN-960 Application Note,
RS-485/RS-422
Circuit Implementation Guide.
Although the
ADM2682E/ADM2687E
have a built-in receiver
fail-safe for the bus idle condition, there are footprints on the
evaluation board for fitting the R3 and R1 pull-up resistors to
VISO on A and Y, as well as the R4 and R2 pull-down resistors
to GND on B and Z. These resistors can be fitted if the user is
connecting to other parts that require such external biasing resis-
tors on the bus. The exact value required for a 200 mV minimum
differential voltage in the bus idle condition depends on the 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.
Evaluation Board User Guide
DECOUPLING AND RESERVOIR CAPACITORS
The evaluation board uses the following decoupling and
reservoir capacitors:
•
On the logic side of the board, the C1 and C2 capacitors
should be 10 μF and 100 nF ceramic capacitors, respectively,
and the C4 and C6 capacitors should be 10 nF and 100 nF
ceramic capacitors, respectively.
On the bus side of the board, the C5 and C7 capacitors
should be 10 nF and 100 nF, respectively, and the C8 and
C9 capacitors should be 100 nF and 10 μF, respectively.
•
BOARD INTERNAL LAYER THICKNESS
The
ADM2682E/ADM2687E
evaluation board consists of
six layers with four internal layers. The spacing between the
internal board layers was chosen as specified in Table 2 to
maximize the stitching capacitance on the board.
Table 2. Spacing Between Layers of the Evaluation Board
Layers
1 to 2
2 to 3
3 to 4
4 to 5
5 to 6
Thickness of Space Between Layers (mm)
0.1016
0.2032
0.2032
0.2032
0.1016
Rev. 0 | Page 4 of 12
Evaluation Board User Guide
EVALUATION BOARD SCHEMATICS
UG-317
Figure 3. Schematics of the
ADM2682E/ADM2687E
Evaluation Board
Rev. 0 | Page 5 of 12
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