SMDA05_06 Datasheet, PDF (5/7 Pages) Semtech Corporation – Unidirectional TVS Array for Protection of Four Lines

PROTECTION PRODUCTS
Applications Information
Device Connection for Protection of Four Data Lines
The SMDAxx series of devices are designed to protect up
to four data lines. The devices are connected as follows:
z The SMDAxx are unidirectional devices and are
designed for use on lines where the normal operat-
ing voltage is above ground. Pins 1, 2, 3, and 4 are
connected to the protected lines. Pins 5, 6, 7, and 8
are connected to ground. The ground connections
should be made directly to the ground plane for best
results. The path length is kept as short as possible
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 connectors
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.
Matte Tin Lead Finish
Matte tin has become the industry standard lead-free
replacement for SnPb lead finishes. A matte tin finish is
composed of 100% tin solder with large grains. Since
the solder volume on the leads is small compared to the
solder paste volume that is placed on the land pattern of
the PCB, the reflow profile will be determined by the
requirements of the solder paste. Therefore, these
devices are compatible with both lead-free and SnPb
assembly techniques. In addition, unlike other lead-free
compositions, matte tin does not have any added alloys
that can cause degradation of the solder joint.
SMDA05 through SMDA24
Circuit Diagram
1
8
2
7
3
6
4
5
I/O Line Protection
Typical Connection
To Protected
Device
1
8
2
7
Ground
3
6
4
5
From Connector
 2005 Semtech Corp.
5
www.semtech.com