Texas Instruments | ControlNet Applications With the SN65HVD61 PHY (Rev. A) | Application notes | Texas Instruments ControlNet Applications With the SN65HVD61 PHY (Rev. A) Application notes

Texas Instruments ControlNet Applications With the SN65HVD61 PHY (Rev. A) Application notes
Application Report
SLLA265A – September 2007 – Revised September 2008
ControlNet™ Applications With the SN65HVD61 PHY
Clark Kinnaird ......................................................................................................... Industrial Interface
ABSTRACT
This application note is a guide for using the SN65HVD61 physical layer transceiver
(PHY) for ControlNet industrial data communications network applications. Designers
familiar with existing ControlNet PHY implementations will find guidance for converting
to the SN65HVD61, which offers cost-effective improvements in board space, power
consumption, and robustness. In addition to advice for drop-in replacement, we also
present suggestions for taking advantage of the new features of the SN65HVD61
(hereafter also referred to as the HVD61), including low-voltage MAC interface, signal
diagnostics, and enable/disable functions.
1
2
3
4
5
6
Contents
Introduction to ControlNet ......................................................................... 2
1.1
Overview .................................................................................... 2
1.2
Physical Layer ............................................................................. 3
The SN65HVD61 ControlNet PHY ............................................................... 3
2.1
Circuit Placement with MAC and Transformer ......................................... 3
2.2
Block Diagram of the HVD61 ............................................................ 4
Replacing the Hybrid Module With the HVD61 ................................................. 5
3.1
Compatibility With Existing Solutions ................................................... 6
3.2
Single-Channel Application ............................................................... 9
3.3
Dual-Channel Application ............................................................... 11
Next-Generation Design With the SN65HVD61............................................... 13
4.1
Improved Characteristics ................................................................ 13
4.2
New Functions ............................................................................ 15
4.3
CHIP ENABLE Function................................................................. 16
More Information .................................................................................. 16
5.1
Example Implementations .............................................................. 16
Conclusion ......................................................................................... 17
List of Figures
1
2
3
4
5
6
7
8
9
10
11
12
13
14
ControlNet Applications ............................................................................ 3
HVD61 PHY Connects the MAC to the ControlNet Bus ....................................... 3
HVD61 Block Diagram ............................................................................. 4
Hybrid Package (Single Channel) ................................................................ 5
SN65HVD61 Package (Single Channel) ........................................................ 5
Transmitted Signal Levels ......................................................................... 6
Test Set-up Demonstrates Interoperability of Old and New Transceivers .................. 7
Hybrid and Hybrid Communication ............................................................... 8
SN65HVD61 and Hybrid Communication ....................................................... 8
Hybrid and Hybrid Communication – Trigger on Node 1 ...................................... 8
SN65HVD61 and Hybrid Communication – Trigger on Node 1 .............................. 8
Hybrid and Hybrid Communication – Trigger on Node 2 ...................................... 9
SN65HVD61 and Hybrid Communication – Trigger on Node 2 .............................. 9
Schematic for Direct Replacement in Single-Channel Application ......................... 10
ControlNet is a trademark of ODVA.
Rockwell Automation, Allen Bradley are registered trademarks of Rockwell Automation, Inc..
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
1
Introduction to ControlNet
15
16
17
18
19
20
www.ti.com
Dual-Channel SIP Hybrid SN65HVD61 Implementation .....................................
Simplified Test Set-up for EMC Standards ....................................................
Nominal Transfer Function of the SN65HVD61 SIG Feature ...............................
Differential Input (Ch.1) and SIG Output (Ch.2) ...............................................
Engineering Prototype SN65HVD61-to-Hybrid Replacement ...............................
Example SN65HVD61-to-Hybrid Replacement Printed Circuit Board .....................
12
14
15
16
17
17
List of Tables
1
2
3
4
5
Components Used in Interoperability Demonstration .......................................... 7
SN65HVD61 Pin Assignments for Direct Replacement of a Single-Channel Hybrid ..... 9
SN65HVD61 Pin Assignments for Direct Replacement of a Dual-Channel Hybrid ...... 11
Power Supply Requirements .................................................................... 13
EMC Standards ................................................................................... 14
1
Introduction to ControlNet
1.1
Overview
ControlNet is an open standard network that meets the demands of industrial applications requiring high
speed (5 Megabits per second), high throughput with predictable and repeatable transfers of mission
critical data.
ControlNet is one of the network technologies that comprise the family of networks built on the Common
Industrial Protocol. ControlNet meets the demands of real-time, high speed applications at the automation
and control layer for integration of complex control systems such as coordinated drive systems, weld
control, motion control, vision systems, complex batch control systems, process control systems with large
data requirements, and systems with multiple controllers and human-machine interfaces. ControlNet is
effective for systems with multiple PC-based controllers and Programmable Logic Controller (PLC)-to-PLC
and PLC-to-Digital Control System (DCS) communication. ControlNet allows multiple controllers – each
with their own I/O and shared inputs – to talk to each other, with any possible interlocking combination.
ControlNet can be implemented on several different types of media, including copper coax cable, fiber
optic cable, and fiber ring, with variations for media redundancy and intrinsically-safe applications. In this
application note, the discussion is limited to copper coax cable implementations.
ControlNet supports a maximum of 99 nodes, with no minimum distance limitation between nodes. It
offers high network efficiency with multicast of inputs and peer-to-peer data, using a Producer/Consumer
communication model that allows the user to configure devices, control actions, and collect information
over a single network
More information about ControlNet can be obtained from the ControlNet International website:
http://www.odva.org
2
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
The SN65HVD61 ControlNet PHY
www.ti.com
1.2
Physical Layer
ControlNet's coax media specifies RG-6 quad shield cable, which is relatively inexpensive and used
widely in the cable TV industry. The standard provides support for bus, star, or tree topologies to meet
various application needs. Passive taps can be installed anywhere on the trunk with no minimum spacing
requirements.
In a typical ControlNet application, several nodes will be connected to a common bus, as shown in
Figure 1. At any time, only one node should drive the bus; all active nodes continually receive the bus
state. The node, which is actively driving the bus, will sink current through one of the HVD61 drivers,
causing the voltage on the bus to be either differential high or differential low.
75 W
PASSIVE
TAP
(Impedance
Matching)
HVD61 VCC
PASSIVE
TAP
(Impedance
Matching)
PASSIVE
TAP
(Impedance
Matching)
HVD61 VCC
75 W
HVD61 VCC
1:1:1 XFRM
Figure 1. ControlNet Applications
2
The SN65HVD61 ControlNet PHY
2.1
Circuit Placement with MAC and Transformer
The SN65HVD61 transceiver is a mixed-signal (digital and analog) device that translates the logic signals
between the Media Access Controller (MAC) and the ControlNet bus lines. The logic signals to and from
the MAC are compatible with TTL, LVTTL, or CMOS logic levels. The XF1 and XF3 pins (see Figure 3)
are designed to connect with a pulse transformer as specified by the ControlNet specification.
Figure 2 shows the connections between the MAC and the HVD61. For simplicity, power supply
connections and external protection components are not shown.
RX
CD
CHEN
ControlNet
MAC
VCC
TXEN
ControlNet Bus
HVD61
TX
TXBAR
SIG
Figure 2. HVD61 PHY Connects the MAC to the ControlNet Bus
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
3
The SN65HVD61 ControlNet PHY
2.2
www.ti.com
Block Diagram of the HVD61
Figure 3 shows a block diagram of the HVD61 ControlNet transceiver. Each of the functional blocks is
implemented in proven Linear BiCMOS process technology. The transceiver is packaged in a standard
14-pin small-outline integrated circuit (SOIC). Full specifications for the performance and operating
conditions of the HVD61 are detailed in the SN65HVD61 datasheet available at www.ti.com.
VCC
VDD
3
14
1
RX
_ +
2
CD
CHEN
SIG
TX
4
8
_ +
0.1
12
5
XF1
TSD
TXEN
TX
7
6
10
XF3
9
DGND
11,13
CGND
Figure 3. HVD61 Block Diagram
4
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
Replacing the Hybrid Module With the HVD61
www.ti.com
3
Replacing the Hybrid Module With the HVD61
Rockwell Automation® (formerly Allen Bradley®) has supplied single-channel and dual-channel ControlNet
transceivers for several years. Each hybrid transceiver module implements the requirements of a coax
transceiver when combined with a transformer and certain external components for electromagnetic
compatibility. The hybrid transceiver functionally replaces about 50 discrete surface-mount components, in
a Single-In-line Package (SIP) as shown in Figure 4.
35.5 mm
ALLEN-BRADLEY
1
2
3
4
6
7
8
13.2 mm
9
10
11
12
2.5 mm
28 mm
Figure 4. Hybrid Package (Single Channel)
Figure 5. SN65HVD61 Package (Single Channel)
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
5
Replacing the Hybrid Module With the HVD61
3.1
3.1.1
www.ti.com
Compatibility With Existing Solutions
ControlNet Standard Requirements
All the requirements for ControlNet communications are specified to be measured relative to the bus lines,
which are coupled to the SN65HVD61 by a transformer as shown in Figure 2. Therefore, the transceiver
specifications given in the SN65HVD61 datasheet reflect the bus requirements with additional parameters
needed to ensure that the overall interface performs as needed.
An example of this is the level of the transmitted signal. On the bus, the signal amplitude is required to be
at least 6.9 Vpp when loaded with 37.5 Ω (two 75 Ω termination resistors in parallel). In the HVD61
datasheet, this is assured by specification of the low-state and high-state voltages of the driver outputs at
XF1 and XF3. The outputs are symmetrical and should be driven in complementary phase, so that XF1
presents a high output when XF3 presents a low output, and vice versa. The high output is specified to be
at least VCC-0.05 V, and the low output is specified to be not more than 1.2 V. Even with a VCC supply as
low as 4.75 V, this produces a differential voltage of at least 4.70 V – 1.20 V = 3.50 V. Reflecting this
signal through the 1:1 ControlNet transformer, this minimum bus voltage of ±3.5 V exceeds the
requirement of 6.9 Vpp. Figure 6 illustrates how the HVD61 conforms to the ControlNet requirements for
transmits levels
VCC
VCC-0.05 V
1.2 V
0V
PRE-DRIVE
LOGIC
HIGH
VCC
LOGIC
LOW
ControlNet Bus
6.9Vpp (MIN)
TX+
9.5Vpp (MAX)
XF1
XF3
TX-
PRE-DRIVE
VCC
VCC-0.05 V
1.2 V
0V
Figure 6. Transmitted Signal Levels
6
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
Replacing the Hybrid Module With the HVD61
www.ti.com
3.1.2
Similarity to Hybrid Characteristics
The design of the HVD61 is such that a ControlNet node using the HVD61 has performance that matches
the characteristics of nodes using the existing hybrid transceiver in all critical parameters. This assures
interoperability of networks with mixed old and new types of transceivers. This also assures compatibility
of the HVD61 for applications replacing the existing hybrid transceiver.
To demonstrate interoperability between the HVD61 and hybrid transceivers, the test set-up shown in
Figure 7 was used to observe typical bus signal data. Standard ControlNet components were used to
illustrate a simple application.
NODE 1
COMM.
BRIDGE
NODE 2
COMM.
BRIDGE
TRIGGER
BUS
CHECKER
OSCILLOSCOPE
10 METER CABLE
R
TAP
T
T
R
TAP
Figure 7. Test Set-up Demonstrates Interoperability of Old and New Transceivers
Table 1. Components Used in Interoperability Demonstration
MANUFACTURER
DESCRIPTION
PART NUMBER
Allen-Bradley
ControlNet Communications Bridge
1756-CNBR/D
2
Allen-Bradley
ControlLogix Power Supply
1756-PA72/B
1
Allen-Bradley
ControlLogix 4-Slot Chassis
1756-A4/A
1
Allen-Bradley
Passive Tap
1786 TPR/B
2
75 Ω Coax Terminator
QUANTITY
2
Belden
Quad Shield ControlNet Cable
3092A
Allen-Bradley
Net Checker
1788 CNCHR/A
10 meters
1
The following figures show oscilloscope traces of bus activity with two nodes communicating. In each pair
of figures, the first figure shows two hybrid (old) transceivers communicating, and the second figure shows
one SN65HVD61 (new) and one hybrid (old) transceiver communicating. Note that there is no noticeable
difference in the signaling between the two different combinations.
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
7
Replacing the Hybrid Module With the HVD61
www.ti.com
In Figure 8 and Figure 9, we see two bursts of communication signals, one from Node 1 at the near end of
the cable, and one from Node 2 at the far end of the cable. No particular details are intended, but these
traces give an overview for the total communications sequence. The blue (top) trace in both figures is the
synchronization trigger signal from the bus checker. This trigger signal can be used to select either Node 1
or Node 2 for the more detailed traces to follow.
Figure 8. Hybrid and Hybrid Communication
Figure 9. SN65HVD61 and Hybrid
Communication
In Figure 10 and Figure 11, the synchronization trigger is set for Node 1. The bus signal trace shows the
characteristics of amplitude (>6.9 Vpp) and bit width (either 100 ns or 200 ns depending on Manchester
code symbol) that are appropriate for ControlNet signaling.
8
Figure 10. Hybrid and Hybrid Communication
– Trigger on Node 1
Figure 11. SN65HVD61 and Hybrid
Communication – Trigger on Node 1
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
Replacing the Hybrid Module With the HVD61
www.ti.com
In Figure 12 and Figure 13, the synchronization trigger is set for Node 2. The effects of the cable losses
are evident as some of the higher frequencies have been attenuated, but the signal retains the
characteristics of valid ControlNet signaling.
Figure 12. Hybrid and Hybrid Communication
– Trigger on Node 2
3.2
Figure 13. SN65HVD61 and Hybrid
Communication – Trigger on Node 2
Single-Channel Application
In single-channel applications, one SN65HVD61 can be configured to function in place of one coax
transceiver hybrid (Rockwell Automation part number 94180202). For some applications, the HVD61 may
be used to directly replace the hybrid transceiver, without taking advantage of the additional features the
HVD61 implements. In these applications, Table 2 shows the pin-to-pin equivalence between the SIP
hybrid and the SOIC HVD61.
Table 2. SN65HVD61 Pin Assignments for Direct Replacement of a
Single-Channel Hybrid
HYBRID PIN
SN65HVD61 PIN
1
XF3_A
10
XF3
2
XF1_A
12
XF1
3
TX_A
5
TX
4
TXBAR_A
6
TXBAR
5
No pin
6
RX_A
1
RX
Receiver output
7
VCC
VDD, VCC
5-V supply
8
CD_A
2
CD
Carrier Detect
9
TXEN_A
7
TXEN
Transmit Enable
10
n/c
11
n/c
12
GND
3, 14
Connections to transformer
Complementary transmit inputs
No connection
No connection
9, 11, 13
DGND, GND
Signal grounds
4
CHEN
Chip Enable – connect to Vcc
8
SIG
Signal Strength – no connection
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
9
Replacing the Hybrid Module With the HVD61
www.ti.com
Note that in these direct-replacement applications, both supply lines (Vcc and VDD) should be tied to a
single 5-V supply. Also, all ground pins (DGND and both CGND pins) should be tied to the common signal
ground
3.2.1
External Components
In order to achieve system-level performance similar to the hybrid transceiver, applications replacing the
hybrid with the HVD61 should use the same external components as in previous designs. These external
components include decoupling capacitors on the power supply and protection devices on the bus signals.
During system-level testing with the HVD61, external components were used as suggested by Rockwell
Automation, as shown in Figure 14.
5V
10 mF
16 V
0.1 mF
25 V
3, 14
RX
1
CD
2
5V
4
12
1:1:1 XFRM
XF1
5V
SN65HVD61
TX
5
TXEN
7
TX
10
XF3
30 V
1M
6
9, 11, 13
10 mF
0.01 mF
MOV
2.2 nF
Figure 14. Schematic for Direct Replacement in Single-Channel Application
The 1:1:1 pulse transformer is described by the ControlNet specification, and may be available from
Rockwell Automation. EPCOS (www.epcos.com) also provides a transformer suitable for ControlNet
applications; this is series T4312 with ordering code B78417P8441A005.
The 30-V MOV acts to reduce transient surge voltages. Rockwell Automation in the past has suggested
the Harris part number V30MLA1812TX1884 to help pass surge testing. Littelfuse (www.littelfuse.com)
makes a family of multilayer transient voltage suppressors, which may have similar characteristics to the
Harris part.
The 2.2 nF (2200 pF) capacitor shown in the circuit is optional, and is intended to improve electromagnetic
compatibility performance at the systems level. This capacitor is connected across the transformer from
the primary to the secondary, between VCC on the chip side and chassis ground on the bus side. Since the
isolation rating on the transformer is 500 Vac rms, the capacitor should have a voltage rating of at least
500 Vac.
10
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
Replacing the Hybrid Module With the HVD61
www.ti.com
3.3
3.3.1
Dual-Channel Application
Pin-to-Pin Assignment
In dual-channel (redundant) applications, two SN65HVD61 transceivers can be configured to function in
place of one coax dual transceiver hybrid (Rockwell Automation part number 94180201). For some
applications, the HVD61 devices may be used to directly replace the hybrid transceiver, without taking
advantage of the additional features the HVD61 implements. In these applications, the table below shows
the pin-to-pin equivalence between the SIP hybrid and the two SOIC HVD61 devices.
Table 3. SN65HVD61 Pin Assignments for Direct Replacement of a Dual-Channel Hybrid
HYBRID PIN
SN65HVD61 A PIN
SN65HVD61 B PIN
1
XF3_A
10
XF3 (A)
2
XF1_A
12
XF1 (A)
3
TX_A
5
TX (A)
4
TXBAR_A
6
TXBAR (A)
5
No pin
6
RX_A
7
VCC
8
CD_A
9
TXEN_A
10
TXEN_B
11
RX_B
12
GND
13
CD_B
14
15
1
Connections to transformer (A)
Complementary transmit inputs (A)
RX (A)
Receiver output (A)
VDD, VCC
5V supply
2
CD (A)
Carrier Detect (A)
7
TXEN (A)
Transmit Enable (A)
7
TXEN (B)
Transmit Enable (B)
1
RX (B)
Receiver output (B)
DGND, CGND
Signal grounds
2
CD (B)
Carrier Detect (B)
TXBAR_B
6
TXBAR(B)
Complementary transmit inputs (B)
TX_B
5
TX (B)
16
XF1_B
12
XF1 (B)
17
XF1_B
10
XF3 (B)
4
4
CHEN
Chip Enable – connect to Vcc
8
8
SIG
Signal Strength – make no connection
3, 14
9, 11, 13
3,14
9,11,13
Connections to transformer (B)
Note that in these direct-replacement applications, all supply lines (VCC and VDD) should be tied to a
single 5-V supply. Also, all ground pins (DGND and CGND pins) should be tied to the common signal
ground.
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
11
Replacing the Hybrid Module With the HVD61
3.3.2
www.ti.com
External Components
For a dual-channel application, the same external protection and filtering components are suggested as
for the single-channel application. For simplicity, replicate the circuit shown in Figure 14 for each channel.
Figure 15 shows an example implementation of a dual-channel application using two HVD61 devices on a
single single in-line package (SIP) board.
Figure 15. Dual-Channel SIP Hybrid SN65HVD61 Implementation
12
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
Next-Generation Design With the SN65HVD61
www.ti.com
4
Next-Generation Design With the SN65HVD61
4.1
Improved Characteristics
4.1.1
1. Operating Temperature to 100°C
The HVD61 is characterized for operation over the temperature range of –40°C to 100°C. This gives
system designers more latitude compared to previous implementations, which were typically limited to
temperature ranges of 0°C to 85°C. As with all designs, proper care must be taken to ensure that the
maximum temperature of any device does not exceed the rated temperature. This involves understanding
not only the ambient temperature, but also the junction temperature rating and thermal design of the
board.
For more information regarding thermal constraints, see the ABSOLUTE MAXIMUM RATINGS table, the
ABSOLUTE MAXIMUM RATINGS table, and the THERMAL CHARACTERISTICS OF IC PACKAGES
section in the SN65HVD61 data sheet. A discussion of thermal modeling and junction temperature
calculations is given in the Texas Instruments Applications Note IC Package Thermal Metrics (TI literature
number SPRA953).
4.1.2
Lower Power Consumption
The quiescent (transmitter off) supply current for hybrid implementations of the ControlNet transceiver is
specified as typically about 50 mA, and can vary to a maximum of almost 75 mA. Under similar conditions
with the chip disabled, the HVD61 supply current is specified as typically about 1.8 mA, with a maximum
of 3 mA. This includes both the analog supply VCC and the digital supply VDD.
In dynamic operating conditions, the active supply current is much higher for both the hybrid-transceiver
and the SN65HVD61 implementation. The load current is supplied through the center-tap of the
transformer, so this is not included as part of the transceiver supply current. The rms supply current to the
hybrid transceiver can typically be as high as 180 mA; the analog rms supply current to the SN65HVD61
is typically about 36 mA, and the digital supply less than 5 mA for a total of about 40 mA.
The load current on the bus is supplied by the 5 V on the bus transformer’s center-tap, independent of
which type of transceiver is used. Assuming that the bus is correctly terminated with 37.5 Ω (75 Ω
impedance at each end), and that the signaling levels meet the ControlNet requirements of ±4.1 V (8.2
Vpp), a nominal current of 109 mA occurs when the transmitter is active. The maximum level of ±4.75 V
(9.5 Vpp) corresponds to a load current of 127 mA.
Table 4. Power Supply Requirements
4.1.3
Transceiver
VCC (5 V)
VDD (2.5 V, 3.3 V, or 5 V)
VCC (5 V) Transformer
Total Power Supply Current
Hybrid (single)
200 mA
Not applicable
130 mA
330 mA
SN65HVD61
65 mA
5 mA
130 mA
200 mA
ESD Protection
4.1.3.1
Chip-Level ESD Protection
Electrostatic discharges constitute a danger for all integrated circuits, including the SN65HVD61.
Electrostatic charging can occur as a result of friction, such as when one walks on a carpet, causing the
body to become charged. If a conducting object such as a piece of equipment connected to a ground line
is touched, the body is discharged. The electrostatic energy stored as charge is injected into the object
that is touched, and is converted primarily into heat. The power dissipation that arises in such cases can
damage the electronic circuits.
Test circuits have been developed to test sensitivity to electrostatic discharges by simulating various
scenarios. These test circuits are analyzed in more detail in the following paragraphs. These should
provide the design engineer with insight into the protection circuits, and whether additional precautions are
necessary.
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
13
Next-Generation Design With the SN65HVD61
www.ti.com
Human-Body Model (HBM) – The HBM test was developed to simulate the action of a human body
discharging accumulated static charge through a device to ground, and employs a series RC network
consisting of a 100-pF capacitor and a 1500-Ω resistor. The SN65HVD61 has been tested and rated for
HBM ESD conditions up to 16 kV on the bus pins, and up to 2 kV on all other pins.
Charged-Device Model (CDM) – The CDM test simulates charging/discharging events that occur in
production equipment and processes. Potential for CDM ESD events occur when there is metal-to-metal
contact in manufacturing. One of many examples is a device sliding down a shipping tube and hitting a
metal surface. The CDM addresses the possibility that a charge may reside on a lead frame or package
(e.g., from shipping) and discharge through a pin that subsequently is grounded, causing damage to
sensitive devices in the path. The discharge current is limited only by the parasitic impedance and
capacitance of the device. CDM testing consists of charging a package to a specified voltage, then
discharging this voltage through the relevant package leads. At TI, the CDM testing is conducted using a
field-induced CDM (FCDM) simulator. The HVD61 has been tested and rated for CDM ESD conditions up
to 500 V on all pins.
Machine Model (MM) – The MM test simulates a machine discharging accumulated static charge through
a device to ground. It comprises a series RC network of a 200-pF capacitor, and nominal series resistance
of less than 1 Ω. The output waveform usually is described in terms of peak current and oscillating
frequency for a given discharge voltage. The HVD61 has been tested and rated for MM ESD conditions up
to 200 V on all pins.
4.1.3.2
Board-Level Protection
The ControlNet network is intended to operate reliably in harsh industrial environments, which often
involve significant electromagnetic-transient events. Ater the HVD61 has been installed in a circuit board,
the applicable levels of transient protection are very dependant on the surrounding components, board
layout, etc. Test specifications such as the IEC-61000-4 series are used to provide a relative measure of
system-level robustness to ESD, voltage surges, and other electromagnetic compatibility (EMC) issues.
End equipment with the SN65HVD61 has been tested to various levels of system-level IEC test standards.
The requirements are summarized in Figure 16 and Table 5.
Table 5. EMC Standards
EMC STANDARD
DESCRIPTION OF TEST METHOD
LEVEL
IEC 61000-4-2
Electro Static Discharge (ESD) Immunity
6 kV Contact 8 kV Air-Gap
IEC 61000-4-3
Radiated Radio Frequency (RF) Immunity
10 V/m at 80 MHz to 2.7GHz
IEC 61000-4-4
Fast Transients / Burst Immunity
1 kV
IEC 61000-4-5
Surge Immunity
1 kV
IEC 61000-4-6
Conducted Radio Frequency (RF) Immunity
10V at 150 kHz to 80 MHz 1 kHz AM 80% modulation
VCC
1:1:1 XFRM
XF1
RG-6 Coax
Passive
ImpedanceMatching
HVD61
VCC
Tap
XF3
30 V
1M
2.2 nF
0.01 mF
IEC stimuli applied here
MOV
10 mF
Figure 16. Simplified Test Set-up for EMC Standards
14
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
Next-Generation Design With the SN65HVD61
www.ti.com
4.2
4.2.1
New Functions
Low-Voltage Interface to MAC
To maintain backward compatibility with previous transceiver implementations, the SN65HVD61 can be
supplied by a single 5 V supply. However, it can also be supplied by split Logic/Bus supplies, to facilitate
operation with MACs using digital supplies down to 2.5 V. The logic supply (VDD) can be any voltage
between 2.375 V (5% below 2.5 V nominal) and 5.25 V (5% above 5 V nominal). The input logic
thresholds for TX, TXBAR, TXEN and CHEN will automatically adjust to standard CMOS logic levels
depending on the value of VDD. That is, logic low will be any voltage below 30% of VDD and logic high
will be any voltage above 70% of VDD. This can eliminate the need for external level-shifters for the case
of MACs with supplies below 5 V.
4.2.2
SIGNAL Function
The Signal Strength output (SIG) is a new function not available on previous implementations of the
ControlNet transceiver. This output provides an analog voltage which is a single-ended version of the
differential voltage across the XF1 and XF3 pins. The SIG function converts the differential voltage to
single-ended, scales the value by 0.1, and offsets the results by 1.25 V. The resulting voltage is then a
suitable representation of the input-bus signal strength, and may be used for network diagnostic functions,
or system built-in tests (BIT). Figure 17 shows the transfer function from differential signal in (XF1,XF3) to
SIG voltage out.
2.5
VO - Output Voltage - VSIG
2
1.5
1
0.5
0
-12
-8
-4
0
4
VID - Differential Input Voltage - V
8
12
Figure 17. Nominal Transfer Function of the SN65HVD61 SIG Feature
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
15
More Information
www.ti.com
Figure 18 shows an oscilloscope trace with the differential signal (Ch.1, top trace) and the SIG voltage
(Ch.2, bottom trace). Note that from the ControlNet bus through the transformer and differential inputs,
there are dynamic effects that distort the higher-frequency content of the SIG output.
Figure 18. Differential Input (Ch.1) and SIG Output (Ch.2)
4.3
CHIP ENABLE Function
The SN65HVD61 implements a Chip Enable (CHEN) feature that was not available on previous
ControlNet transceivers. When the CHEN pin is connected to logic high, the transceiver is fully enabled.
When the CHEN pin is connected to a logic-low level or left disconnected, the transceiver functions are
disabled. In the disabled state, the VCC and VDD power supply currents are very low, less than 3 mA
total. This feature facilitates low power modes for end-equipment using the HVD61.
When the transceiver is re-enabled (rising edge on CHEN), all functions become fully operational in less
than one microsecond.
Note that the CHEN function enables/disables all the functions of the HVD61, while TXEN
enables/disables only the transmitter function.
5
More Information
For more information regarding the ControlNet protocol or Common Industrial Protocol (CIP) of which
ControlNet is part, see the ODVA web site at www.odva.org.
5.1
Example Implementations
The two photographs below show two implementations of using the SN65HVD61 as a direct replacement
for the hybrid transceiver. In the first photo, an engineering version is shown. The surf board can be
quickly wired as shown (refer to Table 2 for pin assignments). These prototype boards are available from
sources such as Capital Advanced Technologies (capitaladvanced.com). The specific board shown in this
figure is Capital Advanced part number 9165.
16
ControlNet™ Applications With the SN65HVD61 PHY
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
Conclusion
www.ti.com
Figure 19. Engineering Prototype SN65HVD61-to-Hybrid Replacement
The second photograph shows an implementation using a small circuit board to carry the SN65HVD61
transceiver and a few other passive components to replace the hybrid SIP transceiver. Note that this
instance is a single-channel application.
Figure 20. Example SN65HVD61-to-Hybrid Replacement Printed Circuit Board
6
Conclusion
The SN65HVD61 integrated ControlNet transceiver gives industrial network designers a new option when
designing products. This transceiver works interchangeably with the older hybrid SIP implementation, but
also offers many advantages in terms of new functions, lower power, and board space savings.
Texas Instruments looks forward to discussing your ControlNet or other industrial interface applications;
contact your local Texas Instruments representative for samples or more information.
SLLA265A – September 2007 – Revised September 2008
Submit Documentation Feedback
ControlNet™ Applications With the SN65HVD61 PHY
17
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products
Amplifiers
Data Converters
DSP
Clocks and Timers
Interface
Logic
Power Mgmt
Microcontrollers
RFID
RF/IF and ZigBee® Solutions
amplifier.ti.com
dataconverter.ti.com
dsp.ti.com
www.ti.com/clocks
interface.ti.com
logic.ti.com
power.ti.com
microcontroller.ti.com
www.ti-rfid.com
www.ti.com/lprf
Applications
Audio
Automotive
Broadband
Digital Control
Medical
Military
Optical Networking
Security
Telephony
Video & Imaging
Wireless
www.ti.com/audio
www.ti.com/automotive
www.ti.com/broadband
www.ti.com/digitalcontrol
www.ti.com/medical
www.ti.com/military
www.ti.com/opticalnetwork
www.ti.com/security
www.ti.com/telephony
www.ti.com/video
www.ti.com/wireless
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2008, Texas Instruments Incorporated
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising