RS-485 Port Protection Evaluation Board 2

RS-485 Port Protection
Evaluation Board 2
Introduction
1
GDT1
GDT2
1
Line B
Unprotected
J3
TISP1
I
II
II
I
II
I
1
2
TVS2
TBU® HSP 2
2
J2
TVS5
2
1
II
3
2
2
MOV2
TVS3 2
GDT3
3
1
TVS1
Load A
NU
3
2
2
MOV1
I
1
2
J1
Protected
2
TBU® HSP 1
1
1
40 mils trace
1
Unprotected
2
TVS4 1
NU
3
1
Line A
1
2
1
This evaluation board serves as an aid in
evaluating circuit protection on RS-485
serial device port solutions using Bourns®
TBU® High-Speed Protector (HSP), MOV
and TVS products to meet the required
industry standards on RS-485 port
interfaces. The recommended Bourns®
TBU® HSP solution offers enhanced
performance features over competing
technologies, which can help the design
engineer to increase the surge & transient
protection level on RS-485 ports and place
the entire circuit protection solution into
a smaller PCB area. Bourns has developed
a RS-485 evaluation board (measuring 50
mm x 25 mm x 1.2 mm) manufactured
using FR4 PCB with nickel gold plating on
top and bottom sides.
TISP2
1
2
2
40 mils trace
Protected
Figure 1
RS-485 Evaluation Board 2 Schematic
Figure 2
RS-485 Evaluation Board 2 Top Side Layout*
Table 1
RS-485 Evaluation Board 2 Bill of Materials
Load B
J4
How to Connect the Evaluation
Board for Test Set-up
• Connect J1 and J2 to the exposed lines.
• Connect J3 and J4 to the RS-485 IC device.
* In addition to the two TBU® HSPs, the default
configuration of this board uses two MOVs (MOV1,
MOV2) and a single TVS diode array (TVS5). The board
allows different configurations:
• 2 MOVs (MOV1 and MOV2) may be replaced by a) 2 single 2031 GDTs (GDT1 and GDT2) or b) a dual 2030 GDT (GDT3)
• 1 TVS diode array (TVS3) may be replaced with a) 2 SMB TVS diodes (TVS1, TVS2) or b) 2 SOT23 TVS diodes (TVS3, TVS4) or c) 2 SOT23-5 thyristor devices (TISP1, TISP2)
No.
Part Number
Qty.
Description
Reference
1
TBU-CA065-300-WH
2
TBU® Single Bidirectional Line 650 V 300 mA
TBU® HSP 1, TBU® HSP 2
2
MOV-10D201K
2
Single Line 10 mm MOV 200 V
MOV1, MOV2
3
CDSOT23-SM712
2
Dual Bidirectional Line 7 V / 12 V
TVS5
10/12 • FU1213
RS-485 Port Protection Evaluation Board 2
Performance Graphs
Run
Trig?
T
PreVu
Trig?
T
T
T
Ch1 Max
329 V
Ch1 Max
545 V
Ch1 Min
-20.5 V
1
4
Ch1 Min
-390 V
1
4
Ch4 Max
11.3 mA
Ch4 Max
1.98 A
Ch4 Min
-81.1 mA
Ch4 Min
-2.55 A
Ch1
500 V
M 10.0 ns
Ch4
5.00 A Ω
Ch 1: input voltage / surge / fault to TBU® HSP
Ch 4: TBU® HSP current
Figure 3
A Ch1
Ch1
-380 V
M 400 ns
Ch4
Figure 4
Trig’d
T
1.00 A Ω
A Ch1
The ohm unit following the current units
shown for Channel 4 (i.e. AOhm)
indicates that a 50 ohm termination was
used internal to the oscilloscope
Surge 1.2/50 5 KV
Run
Trig’d
T
T
116 V
T 31.60 %
Ch 1: input voltage / surge / fault to TBU® HSP
Ch 4: TBU® HSP current
The ohm unit following the current units
shown for Channel 4 (i.e. AOhm)
indicates that a 50 ohm termination was
used internal to the oscilloscope
ESD +8 KV Contact Discharge (IEC-61000-4-2)
Run
200 V
T 20.40 %
T
Ch1 Max
124.4 V
1
4
Ch1 Max
28.3 V
Ch4 Max
365.4 mA
1
4
Ch4 Max
451.8 mA
Ch4 Min
-322.4 mA
Ch1
100 V
M 4.00 ms
Ch4
200 mA Ω
116 V
Ch1
20.0 V
M 4.00 ms
Ch4
T 20.20 %
Ch 1: input voltage / surge / fault to TBU® HSP
Ch 4: TBU® HSP current
Figure 5
A Line
Ch4 Min
-395.7 mA
Figure 6
A Line
116 V
T 20.20 %
Ch 1: input voltage / surge / fault to TBU® HSP
Ch 4: TBU® HSP current
The ohm unit following the current units
shown for Channel 4 (i.e. AOhm)
indicates that a 50 ohm termination was
used internal to the oscilloscope
120 Vrms
200 mA Ω
The ohm unit following the current units
shown for Channel 4 (i.e. AOhm)
indicates that a 50 ohm termination was
used internal to the oscilloscope
28 Vrms
Reference
For more information on implementing advanced circuit protection technologies for RS-485 ports, please review the Bourns RS-485
application note: http://www.bourns.com/data/global/pdfs/bourns_cpk1114_rs485_circuit_protection_appnote.pdf
For further technical support and for complete
circuit protection solutions, please visit
www.bourns.com
10/12 • FU1213
“TBU” is a registered trademark of Bourns, Inc. in the U.S., Taiwan and European Community.
“Bourns” is a registered trademark of Bourns, Inc. in the U.S. and other countries.
COPYRIGHT© 2012 • BOURNS, INC. • 10/12 • e/FU1213