LCDA05_06 Datasheet, PDF (5/8 Pages) Semtech Corporation – Low Capacitance TVS Diode Array For High-Speed Data Interfaces

LCDA05 through LCDA24
PROTECTION PRODUCTS
Applications Information
Device Connection for Protection of Two High-Speed
Data Lines
The LCDAxx is designed to protect up to two high-speed
data lines. The LCDAxx utilizes a low capacitance
compensation diode in series with, but in opposite
polarity to a TVS diode in each line. The resulting
capacitance is less than 5pF per line. Each line will
only suppress transient events in one polarity. There-
fore, to achieve protection in both positive and nega-
tive polarity, a second TVS/rectifier pair is connected in
anti-parallel to the first. Pins 1, 2, 7, and 8 are used to
protect one data line. Pins 3, 4, 5, and 6 are used to
protect the second data line.
The device is connected as follows:
z Pins 1 and 2 are tied together and pins 7 and 8 are
tied together providing the protection circuit for
one I/O line. Pins 3 and 4 are tied together and
pins 5 and 6 are tied together providing the protec-
tion circuit for the second I/O line. Since the
device is electrically symmetrical, either side of the
connected pairs may be used to protect the lines.
The other side of the pair is used to make the
ground connection. The ground connections should
be made directly to the ground plane for best
results. The path length is kept as short as pos-
sible to reduce the effects of parasitic inductance
in the board traces.
Circuit Board Layout Recommendations for Suppres-
sion of ESD.
Good circuit board layout is critical for the suppression
of ESD induced transients. The following guidelines are
recommended:
z Place the TVS near the input terminals or connec-
tors to restrict transient coupling.
z Minimize the path length between the TVS and the
protected line.
z Minimize all conductive loops including power and
ground loops.
z The ESD transient return path to ground should be
kept as short as possible.
z Never run critical signals near board edges.
z Use ground planes whenever possible.
 2005 Semtech Corp.
5
LCDA Connection Diagram
1
I/O 1
2
3
I/O 2
4
8
I/O 1
7
6
I/O 2
5
I/O Line Protection
Connection Options
To Protected
Device
1
Line 1
In/Out
2
8
Line 1
Ground
7
3
Line 2
Ground
4
6
Line 2
In/Out
5
Line 1 1
In/Out
2
3
4
From Connector
To Protected
Device
8
Line 2
In/Out
7
Ground
6
5
From Connector
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