5 2004 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
SMDA05C-5 THRU SMDA24C-5
Circuit Diagram
Connection Diagram
Device Connection for Protection of Five Data Lines
The SMDAxxC-5 is designed to protect up to 5 data or
I/O lines. They are bidirectional devices and may be
used on lines where the signal polarities are above and
below ground.
The SMDAxxC-5 TVS arrays employ a monolithic struc-
ture. Therefore, the working voltage (VRWM) and break-
down voltage (VBR) specifications apply to the differen-
tial voltage between any two data line pins. For ex-
ample, the SMDA24C-5 is designed for a maximum
voltage excursion of ±12V between any two data lines.
The device is connected as follows:
zPins 1, 2, 3, 4, and 5 are connected to the lines
that are to be protected. Pin 8 is 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. Pins 6 and 7 are not connected.
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:
zPlace the TVS near the input terminals or connec-
tors to restrict transient coupling.
zMinimize the path length between the TVS and the
protected line.
zMinimize all conductive loops including power and
ground loops.
zThe ESD transient return path to ground should be
kept as short as possible.
zNever run critical signals near board edges.
zUse 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 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
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4
5
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DATA IN DATA OUT
DATA IN DATA OUT
Applications Information
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.