The MAX149X2 evaluation kit (EV kit) is a fully assembled
and tested PCB that demonstrates the functionality of the
MAX14943 isolated RS-485/PROFIBUS transceiver. The
EV kit operates from a single 3.3V supply and features an
on-board isolated power supply to power the secondary-
side of the circuit.
The MAX149X2 EV kit comes with the MAX14943GWE+
installed, but can also be used to evaluate the pin-compatible
MAX14940, MAX14946, and MAX14949 ICs.
Quick Start
Required Equipment
●
●
●
●
MAX149X2 EV kit
3.3V, 1A DC power supply
Signal/function generator
Oscilloscope
Startup Procedure
1)
2)
3)
4)
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation:
Set the DC power supply to 3.3V and connect the
DC power supply between the EV kits VDDA and
GNDA connectors of the EV kit.
Ensure that J2 and J3 are in their default positions
(see
Table 1).
Turn on the power supply.
Set the signal/function generator to output a 100kHz
0 to 3V square wave. Note: Set the signal/function
generator to operate with a high-impedance load. If
needed, the R1 pad is available to add a 50Ω impedance
to ground.
Connect the signal/function generator to the TXD
test point.
Verify that the A and B outputs switch as the signal
toggles.
Features
●
Operates from a Single 3.3V Supply
●
Terminal Block Connectors for Easy RS-485/
PROFIBUS Evaluation
●
5000VRMS Isolation for 60s
●
Fully Assembled and Tested
●
Proven PCB Layout
Ordering Information
appears at end of data sheet.
5)
6)
Table 1. Jumper Settings (J1–J6)
JUMPER
J1
J2
J3
J4
*Default position.
SHUNT POSITION
1-2
2-3*
1-2*
2-3
Open*
Closed
Open*
Closed
DESCRIPTION
Receiver is disabled. RXD is high impedance.
Receiver is enabled. RXD is active.
Driver is enabled. DEM is high.
Driver is disabled. DEM is low.
DE and
RE
are not connected together.
DE and
RE
are connected together.
A and B are not connected through the on-board 120Ω resistor.
Connects the on-board 120Ω resistor between A and B.
19-7646; Rev 0; 6/15
MAX149X2 Evaluation Kit
Evaluates: MAX14940/MAX14943/
MAX14946/MAX14949
Resistors R2 – R4 Configuration
For end-of-the-line transceivers, close J4 to connect a
120Ω resistor (R3) between the A and B RS-485 I/Os on
the IC.
Pullup and pulldown resistors are generally used on the
receiver inputs to guarantee a known state in the event
that all nodes on the bus are in receive mode, or the
cable becomes disconnected. The exact value for these
resistors varies with the application. Pads are provided for
pullup (R2) and pulldown (R4) resistors for the A-B lines,
although the use of these resistors is purely optional. Note
that the MAX14943 features true fail-safe receiver inputs
that ensure RXD is high when the receiver inputs are
shorted, open, or connected to an idle bus.
Detailed Description of Hardware
The MAX149X2 EV kit is a fully assembled and tested circuit
board for evaluating the MAX14943 isolated RS-485/
Profibus transceiver (U1). The EV kit has been designed
to allow for evaluating the IC alone or in a standard
RS-485 configuration. The EV kit is powered from a single
3.3V power supply.
External Power Supply
The power on the EV kit is derived from a single 3.3V
source. Connect an external supply from GNDA to either
the VDDA test point or P1 connector to supply the 3.3V to
the logic side (A) of the circuit. The integrated push-pull
transformer driver and external transformer (TX1) generate
an isolated supply for powering the (B) isolated side of
the board.
Selecting a Transformer
Table 2
is a list of transformers designed to operate with
the device family. Select the transformer that best meets
the performance requirements of the end application. All
transformers in
Table 2
can be used on the EV kit.
Evaluating the Isolated RS-485 Interface
Driver and Receiver Enable Selection
The EV kit features three jumpers (J1, J2, and J3) to
enable/disable the driver and receiver outputs. Set J1
to 2-3 to enable the receiver. Set J2 to 1-2 to enable the
driver. To actively control both enables, remove J1 and J2
and close J3, which connects DE and
RE
together.
Table 2. Transformer Selection
MANUFACTURER/PART NUMBER
HALO TGMS-1440V6LF
HALO TGMS-1464V6LF
HALO TGMR-1440V6LF
HALO TGMR-1464V6LF
WURTH 750315226
WURTH 750315228
WURTH 750315230
WURTH 750315232
TURNS RATIO
1CT: 1.33CT
1CT:2.4CT
1CT:1.33CT
1CT:2.4CT
1CT:1.3CT
1CT: 2CT
1CT:1.3CT
1CT: 2CT
ISOLATION
VOLTAGE (V
RMS
)
2750
2750
5000
5000
2750
2750
5000
5000
A-SIDE
SUPPLY (V)
5V
3.3V
5V
3.3V
5V
3.3V
5V
3.3V
CAN BE USED WITH MAXIM
PART NUMBERS
MAX14940, MAX14946
MAX14940, MAX14946
MAX14943, MAX14949
MAX14943, MAX14949
MAX14940, MAX14946
MAX14940, MAX14946
MAX14943, MAX14949
MAX14943, MAX14949
www.maximintegrated.com
Maxim Integrated
│
2
MAX149X2 Evaluation Kit
Evaluates: MAX14940/MAX14943/
MAX14946/MAX14949
Ordering Information
PART
MAX149X2EVKIT#
#Denotes RoHS compliant.
TYPE
EV Kit
Component List, PCB Layout, and
Schematic
●
MAX149X2 EV BOM
●
MAX149X2 EV PCB Layout
●
MAX149X2 EV Schematic
See the following links for component information, PCB
layout diagrams, and schematics:
www.maximintegrated.com
Maxim Integrated
│
3
MAX149X2 Evaluation Kit
Evaluates: MAX14940/MAX14943/
MAX14946/MAX14949
Revision History
REVISION
NUMBER
0
REVISION
DATE
6/15
Initial release
DESCRIPTION
PAGES
CHANGED
—
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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