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www.protekdevices.com

05142.R10 4/05

SLVU2.8-4

APPLICATION NOTE

Electronic equipment is susceptible to damage caused by Electrostatic Discharge (ESD), Electrical Fast Transients (EFT), and tertiary lightning

effects. Knowing that equipment can be damaged, the SLVU2.8-4 was designed to provide the level of protection required to safe guard sensitive

equipment. This product can be used in different configurations to provide a level of protection to meet unidirectional line requirements as well as

bidirectional requirements either in a common-mode or differential-mode configuration.

UNIDIRECTIONAL COMMON-MODE CONFIGURATION (Figure 1)

The SLVU2.8-4 provides up to four lines of protection in a common-mode configuration as

depicted in figure 1.

Circuit connectivity is as follows:

✔

Line 1 is connected to Pin 1

✔

Line 2 is connected to Pin 7

✔

Line 3 is connected to Pin 3

✔

Line 4 is connected to Pin 5

✔

Pins 2, 4, 7 and 8 are connected to ground

BIDIRECTIONAL COMMON-MODE CONFIGURATION (Figure 2)

The SLVU2.8-4 provides up to two lines of protection in a common-mode configuration as

depicted in figure 1.

Circuit connectivity is as follows:

✔

Line 1 is connected to Pins 1 & 8

✔

Line 2 is connected to Pins 4 & 5

✔

Pins 2, 3, 6, and 7 are connected to ground

BIDIRECTIONAL DIFFERENTIAL-MODE CONFIGURATION (Figure 3)

The SLVU2.8-4 provides up to two-line pairs of protection in a differenital-mode configuration as

depicted in figure 1.

Circuit connectivity is as follows:

✔

Line Pair 1 is connected to Pins 1 & 2

✔

Line Pair 1 is connected to Pins 7 & 8

✔

Line Pair 2 is connected to Pins 3 & 4

✔

Line Pair 2 is connected to Pins 5 & 6

CIRCUIT BOARD LAYOUT RECOMMENDATIONS

Circuit board layout is critical for Electromagnetic

Compatibility (EMC) protection. The following

guidelines are recommended:

✔

The protection device should be placed near the

input terminals or connectors, the device will

divert the transient current immediately before it

can be coupled into the nearby traces.

✔

The path length between the TVS device and

the protected line should be minimized.

✔

All conductive loops including power and ground

loops should be minimized.

✔

The transient current return path to ground

should be kept as short as possible to reduce

parasitic inductance.

✔

Ground planes should be used whenever

possible. For multilayer PCBs, use ground vias.

Figure 2. Bidirectional Common-Mode Protection

Figure 1. Unidirectional Common-Mode Protection

External diode to ground is a low capacitance

diode of less than 10pF

Figure 3. Bidirectional Differential-Mode Protection