RS-485 Port Protection Evaluation Board 1

Performance Graphs

10/12 • FU1213

Slew Rate 1 KV/µs

Slew Rate 5 KV/µs

Figure 3

Figure 4

Figure 5

Ch 1: Surge generator

Ch 2: Consumed current (TBU® HSP Trigger current)

Note: The noise generated by the GDT when it fires

causes a ground bounce and is reflected in current

measurement at the time the GDT device is triggered.

1

Ch1

Ch1

-172 V

MA

200 ns

31.00 %

1.00 AΩ

Ch4

200 V

Ch1 Max

508 V

Trig?

PreVu

Ch4 Max

1.74 A

T

T

4

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

T

Ch 1: Surge generator

Ch 2: Consumed current (TBU® HSP Trigger current)

Note: The noise generated by the GDT when it fires

causes a ground bounce and is reflected in current

measurement at the time the GDT device is triggered.

1

Ch1

Ch1

312 V

MA

200 ns

30.40 %

1.00 AΩ

Ch4

200 V

Ch1 Max

625 V

PreVu

Ch4 Max

1.64 A

T

T

4

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

T

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_cpk1047_

rs485_circuit_protection_appnote.pdf

“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

For further technical support

and for complete circuit protection solutions,

please visit

www.bourns.com

Ch 1: AC power generator

Ch 2: Voltage on protected side of world (downstream

of TBU® device at SMBJ12CA TVS diode side)

Ch 4: Current consumed (TBU® HSP trigger current)

1

Ch1

Line

-3.98 V

MA

2.00 ms

27.20 %

20.0 V

200 mAΩ

Ch2

Ch4

200 V

Ch1 RMS

126.7 V

Trig’d

Run

Ch4 Max

371.2 mA

Ch4 Min

-359.9 mA

T

T

2

4

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

T