SP504AN Datasheet, PDF (2/11 Pages) Sipex Corporation – Application Note

SP504 - Overvoltage and ESD Protection Using Transzorbs
+5V
22µF
1N5819
22µF
28 31 25 27 26 30
C2+ C2- _VCC V_DD C1+ C1- ₃₂
V_SS
SP504CF
Drivers
TxD
14
22µF
DTR
13
RTS
16
15 14 13 12 11 10
TxC
15
ST
22
2 34 567
RL
17
ProTek Devices
SM16LC15C
LL
24
Receivers
RxD
1
RxC
20
CTS
80
DSR
15 14 13 12 11 10
78
DCD
ProTek Devices
SM16LC15C
19
RI
2 34 567
21
SCT
79
* - 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.
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 of the TVS can be as low as 5V and high as
wm
15V to cover the RS-232 voltage levels. However,
the RS-232 3kΩ 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
SP504AN
SP504 Application Note
2
© Copyright 2000 Sipex Corporation