SR70 RailClamp Low Capacitance TVS Diode Array

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1 RailClamp Description RailClamps are surge rated diode arrays designed to protect high speed data interfaces. The SR7 has been specifically designed to protect sensitive components which are connected to data and transmission lines from overvoltages caused by electrostatic discharge (ESD), electrical fast transients (EFT), and lightning. The SR7 has been optimized for use on ADSL and other highspeed interfaces. The unique design of the SR7 integrates four surge rated, low capacitance steering diodes in a low profile SOT3 package. It has a typical capacitance of only 5pF and may be used to protect two highspeed lines without sacrificing signal integrity. The SR7 is designed to replace standard rectifiers that are not rated for the high energy surges that are normally expected in telecommunications applications. During transient conditions, the steering diodes direct the transient to either the positive side of the power supply line or to ground. The maximum clamping voltage seen by the protected circuit will be one diode drop (V F ) above the supply (reference) voltage. The SR7 may be used as a stand alone device or in conjunction with TVS diodes for enhanced protection. SR7 RailClamp Low Capacitance TVS Diode Array Features Transient protection for high speed data lines to IEC 62 (ESD) ±5kV (air), ±8kV (contact) IEC 6 (EFT) A (5/5ns) IEC 65 (Lightning) kv, 2A (8/2µs) Array of surge rated, low capacitance diodes Protects two I/O lines Low capacitance (5pF typical) for highspeed interfaces Low clamping voltage Solidstate siliconavalanche technology Mechanical Characteristics JEDEC SOT3 package UL 97B listed Molding compound flammability rating: UL 9V Marking: R7 Packaging: Tape and Reel per EIA 8 Applications ADSL Lines I 2 C Bus Protection Video Line Protection T/E secondary IC Side Protection Portable Electronics Microcontroller Input Protection WAN/LAN Equipment ISDN S/T Interface Circuit Diagram Schematic & PIN Configuration Pin Pin 2 Pin Pin SOT3 (Top View) Revision 3/3/6

2 SR7 Absolute Maximum Rating Rating Symbol Value Units Peak Pulse Current (t = 8/2µs) I p P Rectifier Repetitive Peak Reverse Voltage V RM P R 2 A 7 V ESD per IEC 62 (Air) ESD per IEC 62 (Contact) V ESD 5 8 kv Lead Soldering Temperature T L 26 ( sec. ) C Operating Temperature T J 55 to +25 C Storage Temperature T STG 55 to +5 C Electrical Characteristics (T=25 o C) SR7 Parameter Symbol Conditions Minimum Typical Maximum Units Peak Reverse Reverse StandOff Voltage Breakdown Voltage V RRM 7 V B I t = 5µA 85 V V R Reverse Leakage Current I R V RWM = 7V, T=25 C 5 µ A Forward Forward Forward Clamping Voltage Clamping Voltage Clamping Voltage V FC V FC V FC I PP I PP I PP = A, t = 8/2µ s. 5 V p = A, t = 8/2µ s 3. 3 V p = 2A, t = 8/2µ s 7 V p Junction Capacitance C j Between I/O pins and Ground = V, f = MHz V R Between I/O pins = V, f = MHz V R 5 pf 3 pf 26 Semtech Corp. 2

3 SR7 Typical Characteristics NonRepetitive Peak Pulse Power vs. Pulse Time Power Derating Curve Peak Pulse Power PPk (kw)... Pulse Duration tp (µs) % of Rated Power or IPP Ambient Temperature T A ( o C) Pulse Waveform Capacitance vs. Reverse Voltage Percent of I PP Waveform Parameters: 9 tr = 8µs 8 td = 2µs 7 e t 6 5 td = I PP/ Time (µs) % Change in Capacitance I/O to GND f = MHz Reverse Voltage V R (V) Forward Voltage vs. Forward Current 9 Forward Voltage V F (V) Waveform Parameters: tr = 8µs td = 2µs Forward Current I F (A) 26 Semtech Corp. 3

4 SR7 Applications Information Device Connection Options for Protection of Two HighSpeed Data Lines The SR7 is designed to protect two data lines from transient overvoltages 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 2 and 3. The negative reference (REF) is connected at pin. 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. The options for connecting the positive reference are as follows:. To protect data lines and the power line, connect pins 2 and 3 directly to the positive supply rail (V CC ). In this configuration the data lines are referenced to the supply voltage. An external TVS diode may be added between the supply rail and ground in order to prevent overvoltage on the supply rail. 2. In applications where no positive supply reference is available, or complete supply isolation is desired, an external TVS diode may be used as the reference. 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). SR7 Pin Configuration Data Line and Power Supply Protection Using Vcc as reference 2 3 Matte Tin Lead Finish Matte tin has become the industry standard leadfree replacement for SnPb lead finishes. A matte tin finish is composed of % 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 leadfree and SnPb assembly techniques. In addition, unlike other leadfree compositions, matte tin does not have any added alloys that can cause degradation of the solder joint. 26 Semtech Corp.

5 SR7 Outline Drawing SOT3 D A e e e/2 3 2 B E bxn bbb E C A B SEATING PLANE C GAUGE PLANE.25 H SIDE VIEW DETAIL A L L c SEE DETAIL A DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM MAX A A A b b c D E E e BSC e.8.2 BSC L L (.2) (.5) N 8 8 aaa.6.5 bbb.8.2 ccc.. A2 A X ccc C SEATING PLANE b aaa C A B A C NOTES:. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS A AND B TO BE DETERMINED AT DATUM PLANE H 3. DIMENSIONS "E" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.. REFERENCE JEDEC STD TO253, VARIATION D. Land Pattern SOT3 X X Z C G E2 E Y Y DIMENSIONS DIM INCHES MILLIMETERS C (.87) (2.2) E E2 G X X2.7.2 Y Z X2 X NOTES:. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 2. REFERENCE IPCSM782A. 26 Semtech Corp. 5

6 SR7 Marking Codes Part Number Marking Code SR7 R7 R7 SR7 Marking (Top View) Ordering Information Part Number Lead Finish Qty per Reel Reel Size SR7.TC SR7.TCT SnPb 3, 7 Inch Pb Free 3, 7 Inch Leadfree version is RoHS/WEEE Compliant Contact Information Semtech Corporation Protection Products Division 2 Flynn Rd., Camarillo, CA 932 Phone: (85)982 FAX (85) Semtech Corp. 6