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http://www.union-ic.com Rev.03 Sep.2015

4/8

UESD6V8V4X

Application Information

Device Connection Options for Protection of Four High-Speed Data Lines

This device is designed to protect data lines by clamping them to a fixed reference. When the voltage

on the protected line exceeds the reference voltage the steering diodes are forward biased, conducting

the transient current away from the sensitive circuitry. Data lines are connected at pins 1, 3, 4 and 6.

Pin 2 should be connected directly to a ground plane. The path length is kept as short as possible to

minimize parasitic inductance. The positive reference is connected at pin 5. The options for

connecting the positive reference are as follows:

1. To protect data lines and the power line, connect pin 5 directly to the positive supply rail (VCC). In

this configuration the data lines are referenced to the supply voltage. The internal TVS diode prevents

over-voltage on the supply rail.

2. In applications where the supply rail does not exit the system, the internal TVS may be used as the

reference. In this case, pin 5 is not connected. The steering diodes will begin to conduct when the

voltage on the protected line exceeds the working voltage of the TVS (plus one diode drop).

3. In applications where complete supply isolation is desired, the internal TVS is again used as the

reference and

VCC is connected to one of the I/O inputs. An example of this configuration is the protection of a

SIM port. The

Clock, Reset, I/O, and VCC lines are connected at pins 1, 3, 4, and 6. Pin 2 is connected to ground

and pin 5 is not connected.

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

compared 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.