4

www.protekdevices.com

05018.R6 8/03

LCD05C

thru

LCD24C

APPLICATION NOTE

The LCA Series are low capacitance, bidirectional TVS arrays that are designed to protect I/O or high speed data lines from the damaging effects of

ESD or EFT. This product series has a surge capability of 800 Watts P

BIDIRECTIONAL COMMON-MODE CONFIGURATION (Figure 1)

Ideal for use in USB applications, the LCD Series provides up to eight (8) lines of protection in a common-mode configuration as depicted in Figure

1.

Circuit connectivity is as follows:

✔

Pins 2, 3, 4, 5, 6, and 7 are connected to ground.

✔

Pins 15 and 14 connected to Port #1 D- and D+.

✔

Pins 13 and 12 connected to Port #2 D+ and D-.

✔

Pins 11 and 10 connected to Port #3 D+ and D-.

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. By placing the TVS

close to the connectors, the device will divert the

transient current immediately before it can be

coupled into the nearby traces.

✔

The path length between the TVS devices 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.

Figure1. Typical Common- Mode USB Protection Circuit

D+

D-

D+

D-

D-

D+

USB OUTPUT

CONNECTOR

USB

IC

USB OUTPUT

CONNECTOR

D+

D-

34

2

1

58

7

6

16

15

14

13

12

11

10

9

PORT #1

PORT #2

PORT #4

PORT #3