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 2004 Semtech Corp.

www.semtech.com

PROTECTION PRODUCTS

PROTECTION PRODUCTS

SD05 and SD12

Device Connection Options

The SDxx TVS diodes are designed to protect one data,

I/O, or power supply line. The device is designed to

replace multi-layer varistors (MLVs) in portable

applications. It is easily implemented on existing 0805

MLV pads and is only slightly larger than 0603 MLV

pads. The device is unidirectional and may be used on

lines where the signal polarity is above ground. The

cathode band should be placed towards the line that is

to be protected.

Circuit Board Layout Recommendations for Suppres-

sion of ESD.

Good circuit board layout is critical for the suppression

of fast rise-time transients such as ESD. The following

guidelines are recommended (Refer to application note

SI99-01 for more detailed information):

Place the TVS near the input terminals or

connectors to restrict transient coupling.

Minimize the path length between the TVS and

the protected line.

The ESD transient return path to ground should

be kept as short as possible.

Place a TVS and decoupling capacitor between

power and ground of components that may be

vulnerable to electrostatic discharges to the

ground plane.

Minimize all conductive loops including power

and ground loops.

Use multilayer boards when possible.

Minimize interconnecting line lengths

Never run critical signals near board edges.

Fill unused portions of the PCB with ground

plane.

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

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.

Device Schematic and Pin Configuration

Size Comparison to 0805 MLV

SOD-323

0805 MLV

Note: Nominal dimensions in inches

Component Placement Comparison

0805 MLV on

SOD-323 on 0805

MLV Pad

SOD-323 on Recommended

(SOD-323) Solder Pad

0805 Solder Pad

Applications Information