SRDA70-4.TB(2000) Ver la hoja de datos (PDF) - Semtech Corporation
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SRDA70-4.TB Datasheet PDF : 6 Pages
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PROTECTION PRODUCTS
Applications Information
Device Connection Options for Protection of Four
High-Speed Data Lines
The SRDA70-4 TVS is designed to protect four data
lines from transient over-voltages by clamping them to
a fixed reference. When the voltage on the protected
line exceeds the reference voltage (plus diode VF) the
steering diodes are forward biased, conducting the
transient current away from the sensitive circuitry.
Data lines are connected at pins 1, 4, 6 and 7. The
negative reference (REF2) is connected at pins 5 & 8.
These pins should be connected directly to a ground
plane on the board for best results. The path length is
kept as short as possible to minimize parasitic induc-
tance.
The positive reference (REF1) is connected at pins 2 &
3. The options for connecting the positive reference
are as follows:
1. To protect data lines and the power line, connect
pins 2 & 3 directly to the positive supply rail (VCC).
In this configuration the data lines are referenced
to the supply voltage. An external TVS diode may
be added between the supply rail and ground in
order to prevent over-voltage on the supply rail.
2. The SRDA70-4 can be isolated from the power
supply by adding a series resistor between pins 2 &
3 and VCC. A value of 10kW is recommended. The
internal steering diodes remain biased, providing
the advantage of lower capacitance.
3. In applications where no positive supply reference
is available, or complete supply isolation is desired,
an external TVS diode may be used as the refer-
ence. The steering diodes will begin to conduct
when the voltage on the protected line exceeds the
working voltage of the TVS (plus one diode drop).
SRDA70-4
I/O Protection
Microcontroller Protection
SRDA70-4
ã 2000 Semtech Corp.
4
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