SMF3.3
PROTECTION PRODUCTS
Applications Information
SMF3.3
Typical Application Diagram
Circuit Board Layout Recommendations for Suppres-
sion of ESD.
Matte Tin Lead Finish
Matte tin has become the industry standard lead-free
Good circuit board layout is critical for the suppression replacement for SnPb lead finishes. A matte tin finish
of ESD induced transients. The following guidelines are is composed of 100% tin solder with large grains.
recommended:
Since the solder volume on the leads is small com-
pared 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
z
z
z
z
Place the TVS near the input terminals or connec-
tors to restrict transient coupling.
Minimize the path length between the TVS and the
protected line.
Minimize all conductive loops including power and
ground loops.
The ESD transient return path to ground should be have any added alloys that can cause degradation of
kept as short as possible.
the solder joint.
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Never run critical signals near board edges.
Use ground planes whenever possible.
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