4

 2004 Semtech Corp.

www.semtech.com

PRELIMINARY

PROTECTION PRODUCTS

SMF05C

13

4

5

6

2

SMF05C Circuit Diagram

Protection of Five Unidirectional Lines

Device Connection for Protection of Five Data Lines

The SMF05C is designed to protect up to five unidirec-

tional data lines. The device is connected as follows:

1. Unidirectional protection of five I/O lines is

achieved by connecting pins 1, 3, 4, 5 and 6 to the

data lines. Pin 2 is connected to ground. The

ground connection 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:

Place the SMF05C near the input terminals or

connectors to restrict transient coupling.

Minimize the path length between the SMF05C and

the protected line.

Minimize all conductive loops including power and

ground loops.

The ESD transient return path to ground should be

kept as short as possible.

Never run critical signals near board edges.

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 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.

Applications Information