4

www.protekdevices.com

05066.R4 8/03

PSOT03LC

thru

PSOT36LC

APPLICATION NOTE

The PSOTxxLC Series are low capacitance TVS arrays designed to protect I/O or data lines from the damaging effects of ESD or EFT. This product

series provides unidirectional & bidirectional protection, with a surge capability of 500 Watts P

40 kilovolts.

BIDIRECTIONAL COMMON-MODE CONFIGRUATION (Figure 1)

Two PSOTxxLC devices, when used in paralell, provide protection in a

common-mode configuration as depicted in Figure 1.

Circuit connectivity is as follows:

✔

I/O Line is connected to Device 1, Pin 1.

✔

I/O Line is connect to Device 2, Pin 2.

✔

Device 1, Pin 2 is connected to ground.

✔

Device 2, Pin 1 is connected to ground.

✔

Device 1 & 2, Pin 3 is not connected.

BIDIRECTIONAL DIFFERENTIAL-MODE CONFIGRUATION (Figure

1)

In addition, two PSOTxxLC devices, when used in paralell, provide

protection in a differential-mode configuration for Ethernet applications as

depicted in Figure 2.

Circuit connectivity is as follows:

✔

I/O Line 1 is connected to Device 1, Pin 1.

✔

I/O Line 1 is connect to Device 2, Pin 2.

✔

I/O Line 2 is connected to Device 1, Pin 1.

✔

I/O Line 2 is connect to Device 2, Pin 2.

✔

Device 1 & 2, Pin 3 is not connected.

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 1 - Common-Mode I/O Port Protection

3

1

2

3

1

2

I/O LINE

GND

Figure 2 - Differential-Mode Ethernet Protection

3

1

2

3

1

2

I/O 1

I/O 2