Texas Instruments ISO1176T, ISO3086T, ISO35T User Manual
User's Guide
SLLU122A–April 2010–Revised July 2010
ISO1176T/35T/3086T Evaluation Module
This document describes the ISO1176T/35T/3086T Evaluation Module (EVM). It is used to evaluate the
ISO1176T PROFIBUS™ Transceiver, the ISO35T RS-485 Transceiver, or the ISO3086T RS-485
Transceiver. Because the devices are similar transceivers, and the printed-circuit board is the same for all
three EVMs, this manual can be used for all three devices.
The EVM can be used to evaluate device parameters while acting as a guide for board layout. The board
allows for the connection of 50-Ω coaxial cables via QuietZone connectors. It also provides easy
connection points for oscilloscope probes. Banana jacks are provided for connection of a dc power supply.
These features provide the designer with a tool for evaluation and the successful design of an
end-product.
Contents
1 Overview ..................................................................................................................... 2
2 Recommended Equipment ................................................................................................ 8
List of Figures
1 ISO1176T Device Pinout and Block Diagram........................................................................... 3
2 ISO35T Device Pinout and Block Diagram.............................................................................. 3
3 ISO3086T Device Pinout and Block Diagram........................................................................... 3
4 ISO1176T/35T/3086TEVM Board......................................................................................... 5
5 Point-to-Point Simplex Circuit ............................................................................................. 6
6 Parallel Terminated Simplex Circuit ...................................................................................... 6
7 Five-Node Multipoint Circuit ............................................................................................... 7
8 Two-Node Multipoint Circuit ............................................................................................... 7
9 EVM Configuration for Inducing a Ground Potential Difference Voltage Between Nodes ........................ 8
10 PCB Top Layer ............................................................................................................ 12
11 Silk Screen – Top Side ................................................................................................... 13
12 Signal Traces – Bottom Layer ........................................................................................... 14
13 Silkscreen – Bottom Layer ............................................................................................... 15
1 EVM Configuration Options for ISO1176T............................................................................... 8
2 EVM Configuration Options for ISO35T and ISO3086T ............................................................... 9
3 ISO1176TEVM Bill of Material ........................................................................................... 10
4 ISO35TEVM Bill of Materials............................................................................................. 11
5 ISO3086TEVM Bill of Materials.......................................................................................... 11
SLLU122A–April 2010–Revised July 2010 ISO1176T/35T/3086T Evaluation Module
List of Tables
1
Copyright © 2010, Texas Instruments Incorporated
Overview
1 Overview
This EVM allows for evaluation of either the ISO1176T PROFIBUS™ or ISO35T or ISO3086T RS-485
transceivers. The EVM comes with a single transceiver installed on the circuit board (U1), but any of the
three devices can be evaluated using this single printed-circuit board (PCB). The PCB also contains a
transformer and voltage regulator that is used to provide dc power to the right (bus) side of the device.
Because all three devices contain the output oscillator signals used to drive the transformer, any of the
three devices can be evaluated using this single PCB. Note that two different transformers and voltage
regulators can be installed on the PCB. One set is used to generate +3.3 Vdc for the ISO35T device,
which is specified for 3.3-Vdc operation. The other set is installed on the ISO1176TEVM and
ISO3086TEVM to generate +5-Vdc power required for those two devices. These three integrated circuits
(ISO1176T, ISO35T, and ISO3086T) all contain the integrated transformer driver and are footprint
compatible. The major difference is the +5-Vdc or +3.3-Vdc operation.
Care needs to be taken regarding the isolated power and ground, as this is an isolating device. Power and
ground for the Data/Control side of the device (pins D, R, DE, RE\, D1, and D2) can be completely
isolated from power and ground for the Bus side of the device (pins A, B, etc.). Although these devices are
designed to operate with an isolation voltage up to 4000 V, this PCB is not. To ensure user safety while
using the EVM, the PCB has been designed to support an isolation voltage of approximately 500 V. The
user must be careful when using the EVM to test isolation voltage.
Finally, the ISO1176TEVM allows half-duplex operation, whereas the ISO35T and ISO3086T are
full-duplex devices. The PCBs are configured for either half- or full-duplex operation in their as-shipped
configuration. Changes between configurations can easily be done using the notes provided on the
schematic. The EVMs allow the user to evaluate half-duplex point-to-point or multidrop (PROFIBUS)
systems, or multipoint (RS-485) applications using multiple EVMs.
The ISO1176T meets or exceeds the requirements of EN50170 and the ISO35T and ISO3086T meet or
exceed the requirements of TIA/EIA RS-485 while providing 4000 V of isolation between the Data/Control
and Bus sides of the device. Each device has specific features, such as receiver hysteresis, low bus
capacitance, and failsafe receiver output for bus open, short, or idle conditions. These devices also
support extremely fast data rates or 1 Mbps (ISO35T), 20 Mbps (ISO3086T), or 40 Mbps (ISO1176T).
These features all contribute to making the ISO1176T, ISO35T, or ISO3086T an excellent choice for use
in industrial and factory environments.
www.ti.com
CAUTION
Note that although the device provides galvanic isolation of up to 4000 V, this
EVM cannot be used for isolation voltage testing. It is designed for the
examination of device operating parameters only and may be damaged if high
voltage (>500 V) is applied across the isolation barrier or if a voltage >5.5 V is
applied to any device pin.
The data sheet for three devices is available on the TI Web site. A pinout of each device and functional
block diagram are in Figure 1 through Figure 3.
PROFIBUS is a trademark of PROFIBUS Nutzerorganisation e V.
2
ISO1176T/35T/3086T Evaluation Module SLLU122A–April 2010–Revised July 2010
Copyright © 2010, Texas Instruments Incorporated
functiondiagram
DE
8
D
R
5
6
RE
ISODE
10
B
A
13
12
7
GALVANICISOLATION
OSC
1
2
D2
D1
1
2
3
4
5
6
7
8 9
10
11
12
13
14
15
16
RE
R
D
V
CC2
B
A
GND2
DE
DW PACKAGE
(TOP VIEW)
V
CC1
GND2
ISODE
D1
D2
GND1
GND2
GND2
functiondiagram
DE
6
D
5
R
3
4
RE
B
A
14
13
GALVANICISOLATION
OSC
1
2
D2
D1
12
11
Z
Y
1
2
3
4
5
6
7
8 9
10
11
12
13
14
15
16
R
RE
D
D1
V
CC2
Y
Z
GND2
DE
DW PACKAGE
(TOP VIEW)
V
CC1
GND1
GND2
D2
B
A
GND2
functiondiagram
DE
6
D
5
R
3
4
RE
B
A
14
13
GALVANICISOLATION
OSC
1
2
D2
D1
12
11
Z
Y
1
2
3
4
5
6
7
8 9
10
11
12
13
14
15
16
R
RE
D
D1
V
CC2
Y
Z
GND2
DE
DW PACKAGE
(TOP VIEW)
V
CC1
GND1
GND2
D2
B
A
GND2
www.ti.com
Overview
Figure 1. ISO1176T Device Pinout and Block Diagram
Figure 2. ISO35T Device Pinout and Block Diagram
Figure 3. ISO3086T Device Pinout and Block Diagram
1.1 PROFIBUS/RS-485
The TIA/EIA-485 (also known as RS-485) standard was created in response to a demand from the data
communications community for a general-purpose, high-speed balanced interface standard for multipoint
applications. The standard, Electrical Characteristics of Generators and Receivers for Use in Balanced
Digital Multipoint Systems, specifies differential signaling drivers and receivers for data interchange across
half-duplex or multipoint data bus structures. Although TIA/EIA-485 specifies requirements for drivers and
receivers operating at a signaling rate up to 10 Mbps, the standard also states that devices meeting the
electrical characteristics of the standard:
SLLU122A–April 2010–Revised July 2010 ISO1176T/35T/3086T Evaluation Module
Copyright © 2010, Texas Instruments Incorporated
3
Overview
…."need not operate over the entire data signaling rate range specified nor be limited to 10Mbps. They
may be specified to operate at data rates to satisfy specific applications. The upper bound is application
dependent and beyond the scope of this standard. Maximum signaling rate is typically limited by the
following: ratio of signal transition time to the unit interval, maximum allowable stub length, and the
bandwidth of the interconnecting media."
PROFIBUS (Process Field Bus), developed subsequently, had several impacts on the electrical (physical)
layer including an increase in the receiver noise margin, to allow the bus to be used in an extremely noisy
(i.e., EMI-rich) environment. This was accomplished by increasing the minimum differential voltage on the
bus. The ISO1176T has been designed specifically for these types of environments. The two standards
are indeed very similar.
1.2 EVM Kit Contents
1.2.1 ISO1176TEVM Kit Contents
ISO1176TEVM circuit board with ISO1176TDW installed - (6510416-1)
This PCB is configured with a DA2304-AL transformer and LP2985A-50DBVR LDO for 3-V to 5-V
operation on the logic side of the device and 5-V operation on the bus side.
1.2.2 ISO35TEVM Kit Contents
ISO35TEVM circuit board with ISO35TDW installed – (6510416-2)
This PCB is configured with a DA2303-AL transformer and LP2985A-33DBVR for 3-V operation on the
logic and bus sides of the device.
www.ti.com
1.2.3 ISO3086TEVM Kit Contents
ISO3086TEVM circuit board with ISO3086TDW installed - (6510416-3)
This PCB is configured with a DA2304-AL transformer and LP2985A-50DBVR LDO for 3-V to 5-V
operation on the logic side of the device and 5-V operation on the bus side.
The ISO1176T/35T/3086TEVM is shown in Figure 4.
4
ISO1176T/35T/3086T Evaluation Module SLLU122A–April 2010–Revised July 2010
Copyright © 2010, Texas Instruments Incorporated
www.ti.com
Overview
1.3 Configurations
The ISO1176T/35T/3086TEVM board allows the user to evaluate performance of any of the three devices,
or to connect easily to an existing PROFIBUS or RS-485 bus to evaluate system performance in an
existing system. Also, multiple EVMs can be obtained to allow the user to construct various bus
configurations. With just two EVMs, the user may evaluate performance of a point-to-point simplex,
parallel-terminated point-to-point simplex, and two-node multipoint operation. When using multiple EVMs,
all of these modes of operation can be configured through onboard jumpers, external cabling, and the
R7–R10 resistors.
SLLU122A–April 2010–Revised July 2010 ISO1176T/35T/3086T Evaluation Module
Figure 4. ISO1176T/35T/3086TEVM Board
5
Copyright © 2010, Texas Instruments Incorporated
EVM1 EVM2
Disabled Disabled
R9andR10Removed
T
EVM1 EVM2
Disabled Disabled
T
T
Overview
1.3.1 Point-to-Point
The point-to-point configuration is shown in Figure 5. This configuration requires two EVMs, and although
this is not the intended mode of operation for PROFIBUS/RS-485 devices, it is used for high noise or
longer (higher loss) transmission lines. Due to the increased drive current, a single 100-Ω termination
resistor on the EVM results in a differential bus voltage (Vod) twice as large as the normally doubled
terminated line. This practice is acceptable as long as the combination of input voltage and common-mode
voltage does not exceed absolute maximum ratings of the line circuits.
This configuration is shown in Figure 5. It consists of a single driver on the left, and a single receiver on
the right. Note that the termination resistors (R9 and R10) have been removed from the driver EVM.
This configuration shows the receiver disabled on the driver (JUMP2 connected to Vcc) EVM and the
driver disabled on the receiver EVM (JMP4 tied to GND1). Note that with only a single termination, the
differential bus voltage is higher than normal.
www.ti.com
Figure 5. Point-to-Point Simplex Circuit
This configuration also can have a termination at the source and load (parallel terminated as shown
Figure 6) thereby, keeping nominal PROFIBUS/RS-485 signal levels.
Figure 6. Parallel Terminated Simplex Circuit
1.3.2 Multipoint
The multipoint configuration is the primary application of PROFIBUS/RS-485. The RS-485 standard allows
for any combination of drivers, receivers, or transceivers up to a total of 32 unit loads on the line. The
ISO1176T device allows the total number of nodes to be increased because ISO1176T represents just 1/5
of a unit load. This allows up to 160 nodes to be connected onto a single bus. Figure 7 shows a
representation of a five-node multipoint configuration using five ISO1176T transceivers. Increased drive
current in addition to the wide common-mode input, allows this ISO1176T PROFIBUS transceiver to drive
multiple receivers over longer line lengths. Notice that the termination resistors (R9 and R10) are only
installed on the EVMs at each end of the bus.
6
ISO1176T/35T/3086T Evaluation Module SLLU122A–April 2010–Revised July 2010
Copyright © 2010, Texas Instruments Incorporated
Loading...