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SRV05-4 Datasheet(PDF) 5 Page - Semtech Corporation |
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SRV05-4 Datasheet(HTML) 5 Page - Semtech Corporation |
5 / 12 page ![]() 5 2004 Semtech Corp. www.semtech.com PROTECTION PRODUCTS SRV05-4 Device Connection Options for Protection of Four High-Speed Data Lines The SRV05-4 TVS is designed to protect four data lines from transient over-voltages by clamping them to a fixed reference. When the voltage on the protected line exceeds the reference voltage (plus diode V F) 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. The negative reference (REF1) is connected at pin 2. This pin should be connected directly to a ground plane on the board for best results. The path length is kept as short as possible to minimize parasitic inductance. The positive reference (REF2) 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 (V CC). In this configuration the data lines are referenced to the supply voltage. The internal TVS diode prevents over-voltage on the supply rail. 2. The SRV05-4 can be isolated from the power supply by adding a series resistor between pin 5 and V CC. A value of 100kΩ is recommended. The internal TVS and steering diodes remain biased, providing the advantage of lower capacitance. 3. In applications where no positive supply reference is available, or complete supply isolation is desired, 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). ESD Protection With RailClamps RailClamps are optimized for ESD protection using the rail-to-rail topology. Along with good board layout, these devices virtually eliminate the disadvantages of using discrete components to implement this topology. Consider the situation shown in Figure 1 where dis- crete diodes or diode arrays are configured for rail-to- rail protection on a high speed line. During positive duration ESD events, the top diode will be forward biased when the voltage on the protected line exceeds Data Line and Power Supply Protection Using Vcc as reference Data Line Protection with Bias and Power Supply Isolation Resistor Data Line Protection Using Internal TVS Diode as Reference Applications Information |