PROTECTION PRODUCTS
Description
RailClamps are surge rated diode arrays designed to
protect high speed data interfaces. The SR70 has
been specifically designed to protect sensitive compo-
nents which are connected to data and transmission
lines from over-voltages caused by
ESD
(electrostatic
discharge),
EFT
(electrical fast transients), and
light-
ning.
The SR70 has been optimized for use on ADSL
and other high-speed interfaces.
The unique design of the SR70 integrates four surge
rated, low capacitance steering diodes in a low profile
SOT-143 package. It has a typical capacitance of only
5pF and may be used to protect two high-speed lines
without sacrificing signal integrity. The SR70 is de-
signed to replace “standard” rectifiers that are not
rated for the high energy surges that are normally
expected in telecommunications applications.
During transient conditions, the steering diodes direct
the transient to either the positive side of the power
supply line or to ground. The maximum clamping
voltage seen by the protected circuit will be one diode
drop (V
F
) above the supply (reference) voltage. The
SR70 may be used as a stand alone device or in
conjunction with TVS diodes for enhanced protection.
RailClamp
Low Capacitance TVS Diode Array
Features
Transient protection for high speed data lines to
IEC 61000-4-2 (ESD) ±15kV (air), ±8kV (contact)
IEC 61000-4-4 (EFT) 40A (5/50ns)
IEC 61000-4-5 (Lightning) 1kV, 24A (8/20µs)
Array of surge rated, low capacitance diodes
Protects two I/O lines
Low capacitance (5pF typical) for high-speed
interfaces
Low clamping voltage
Solid-state silicon-avalanche technology
SR70
Mechanical Characteristics
JEDEC SOT-143 package
UL 497B listed
Molding compound flammability rating: UL 94V-0
Marking : R70
Packaging : Tape and Reel per EIA 481
Applications
ADSL Lines
I
2
C Bus Protection
Video Line Protection
T1/E1 secondary IC Side Protection
Portable Electronics
Microcontroller Input Protection
WAN/LAN Equipment
ISDN S/T Interface
Circuit Diagram
Schematic & PIN Configuration
Pin 4
1
Pin 2
Pin 3
4
2
Pin 1
3
SOT-143 (Top View)
Revision 04/18/03
1
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