SP504AN

SP504 Application Note

© Copyright 2000 Sipex Corporation

2

SP504 - Overvoltage and ESD Protection Using Transzorbs

Although the SP504 is internally protected for ESD

and overvoltage, an external transient voltage sup-

pression circuit can be added to increase the level of

protection of the device. This may be desired for

greater ESD protection or clamping the input or out-

put voltages. The maximum driver output and re-

ceiver input voltages should not exceed

±15V.

The SP504 configuration above uses ProTek Devices'

SM16LC15C TVS devices to protect the receiver in-

puts and the driver outputs since these pins are di-

rectly exposed to the connector and the outside world.

The V

15V to cover the RS-232 voltage levels. However,

the RS-232 3k

Ω to 7kΩ input impedance will not

comply if the voltage levels exceed the clamping

voltage of the TVS.

ProTek Devices • Tempe, AZ. • 602-431-8101

22

µF

25

27

26 30

32

1N5819

C1-

C2-

C1+

C2+

22

µF

SP504CF

Drivers

TxD

14

DTR

13

RTS

16

TxC

15

ST

22

RL

17

LL

24

RxD

1

RxC

20

CTS

80

DSR

78

DCD

19

RI

21

SCT

79

Receivers

* - Please note that the ProTek transient

voltage suppressors should also be con-

nected to the other SP504 drivers and re-

ceivers in the same configuration as shown

above.

28

31

22

µF

+5V

15

14 13

12

11 10

23

4

56

7

ProTek Devices

SM16LC15C

ProTek Devices

SM16LC15C

15

14 13

12

11 10

23

4

56

7