SR70 RailClamp Low Capacitance TVS Diode Array PROTECTION PRODUCTS - RailClamp Description Features RailClamps are surge rated diode arrays designed to protect high speed data interfaces. The SR70 has been specifically designed to protect sensitive components which are connected to data and transmission lines from over-voltages caused by electrostatic discharge (ESD), electrical fast transients (EFT), and lightning. The SR70 has been optimized for use on ADSL and other high-speed interfaces. The unique design of the SR70 integrates four surge rated, low capacitance steering diodes in a low profile SOT-143 package. It has a typical capacitance of only 5pF and may be used to protect two high-speed lines without sacrificing signal integrity. The SR70 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 (VF) above the supply (reference) voltage. The SR70 may be used as a stand alone device or in conjunction with TVS diodes for enhanced protection. Transient protection for high speed data lines to IEC 61000-4-2 (ESD) ±15kV (air), ±8kV (contact) IEC 61000-4-4 (EFT) 40A (5/50ns) IEC 61000-4-5 (Lightning) 1kV, 24A (8/20µs) Array of surge rated, low capacitance diodes Protects two I/O lines Low capacitance (5pF typical) for high-speed interfaces Low clamping voltage Solid-state silicon-avalanche technology Mechanical Characteristics JEDEC SOT-143 package UL 497B listed Molding compound flammability rating: UL 94V-0 Marking: R70 Packaging: Tape and Reel per EIA 481 Applications Circuit Diagram ADSL Lines I2C Bus Protection Video Line Protection T1/E1 secondary IC Side Protection Portable Electronics Microcontroller Input Protection WAN/LAN Equipment ISDN S/T Interface Schematic & PIN Configuration Pin 4 1 Pin 2 4 Pin 3 2 3 Pin 1 SOT-143 (Top View) Revision 03/03/06 1 www.semtech.com SR70 PROTECTION PRODUCTS Absolute Maximum Rating R ating Symbol Value Units IP P 24 A Rectifier Repetitive Peak Reverse Voltage V RRM 70 V ESD per IEC 61000-4-2 (Air) ESD per IEC 61000-4-2 (Contact) VESD 15 8 kV Lead Soldering Temperature TL 260 (10 sec.) °C Operating Temperature TJ -55 to +125 °C TSTG -55 to +150 °C Peak Pulse Current (tp = 8/20µs) Storage Temperature Electrical Characteristics (T=25oC) SR70 Parameter Symbol Conditions Minimum Typical Maximum Units 70 V Peak Reverse Stand-Of f Voltage VRRM Reverse Breakdown Voltage VBR It = 50µA Reverse Leakage Current IR VRWM = 70V, T=25°C 5 µA Forward Clamping Voltage VFC IPP = 1A, tp = 8/20µs 1.5 V Forward Clamping Voltage VFC IPP = 10A, tp = 8/20µs 3.3 V Forward Clamping Voltage VFC IPP = 24A, tp = 8/20µs 7 V Junction Capacitance Cj Between I/O pins and Ground VR = 0V, f = 1MHz 5 10 pF Between I/O pins VR = 0V, f = 1MHz 3 2006 Semtech Corp. 2 85 V pF www.semtech.com SR70 PROTECTION PRODUCTS Typical Characteristics Non-Repetitive Peak Pulse Power vs. Pulse Time Power Derating Curve 10 110 % of Rated Power or PI P Peak Pulse Power - PPk (kW) 100 1 0.1 90 80 70 60 50 40 30 20 10 0 0.01 0.1 1 10 100 0 1000 25 Pulse Waveform Percent of IPP 80 -t 50 40 125 150 I/O to GND f = 1MHz -2 % Change in Capacitance 90 e 100 0 Waveform Parameters: tr = 8µs td = 20µs 100 60 75 Capacitance vs. Reverse Voltage 110 70 50 Ambient Temperature - TA (oC) Pulse Duration - tp (µs) td = IPP/2 30 20 -4 -6 -8 -10 -12 -14 10 -16 0 0 5 10 15 20 25 0 30 1 2 3 4 5 6 Reverse Voltage - VR (V) Time (µs) Forward Voltage vs. Forward Current 10 Forward Voltage - V F (V) 9 8 7 6 5 4 3 Waveform Parameters: tr = 8µs td = 20µs 2 1 0 0 5 10 15 20 25 30 35 40 45 50 Forward Current - IF (A) 2006 Semtech Corp. 3 www.semtech.com SR70 PROTECTION PRODUCTS Applications Information SR70 Pin Configuration Device Connection Options for Protection of Two High-Speed Data Lines The SR70 is designed to protect two 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 VF) 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 (REF1) is connected at pin 1. 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 4. The options for connecting the positive reference are as follows: 1 2 1. To protect data lines and the power line, connect pins 2 and 3 directly to the positive supply rail (VCC). 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 over-voltage 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). 4 3 Data Line and Power Supply Protection Using Vcc as reference 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. 2006 Semtech Corp. 4 www.semtech.com SR70 PROTECTION PRODUCTS Outline Drawing - SOT-143 D A e H e/2 DIM 4 3 GAUGE PLANE SEATING PLANE B C 1 A A1 A2 b b1 c D E E1 e e1 L L1 N 0 aaa bbb ccc 0.25 L L1 E E1 c 0 DETAIL A 2 bxN e1 bbb A2 C A B SEE DETAIL A SIDE VIEW A 4X DIMENSIONS INCHES MILLIMETERS MIN NOM MAX MIN NOM MAX .035 - 1.22 .048 0.80 0.15 .006 0.013 .042 0.75 0.90 1.07 .020 0.30 0.51 .037 0.76 0.94 .008 0.08 0.20 .114 .120 2.80 2.90 3.04 .093 .104 2.10 2.37 2.64 .051 .055 1.20 1.30 1.40 .075 1.92 BSC .008 0.20 BSC .015 .020 .024 0.40 0.50 0.60 (.021) (0.54) 4 4 0° 8° 0° 8° .006 0.15 .008 0.20 .004 0.10 .031 .000 .029 .011 .029 .003 .110 .082 .047 ccc C SEATING PLANE A1 b1 aaa C C A B NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. DATUMS -A- AND -B- TO BE DETERMINED AT DATUM PLANE -H- 3. DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 4. REFERENCE JEDEC STD TO-253, VARIATION D. Land Pattern - SOT-143 X1 X1 Y DIM Z C E1 G E2 Y X2 C E1 E2 G X1 X2 Y Z DIMENSIONS INCHES MILLIMETERS (.087) .076 .068 .031 .039 .047 .055 .141 (2.20) 1.92 1.72 0.80 1.00 1.20 1.40 3.60 X1 NOTES: 1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 2. REFERENCE IPC-SM-782A. 2006 Semtech Corp. 5 www.semtech.com SR70 PROTECTION PRODUCTS Marking Codes Part Number Marking Code SR70 R70 R70 SR70 Marking (Top View) Ordering Information Par t Number Lead Finish Qty per Reel R eel Size SR70.TC SnPb 3,000 7 Inch SR70.TCT Pb Free 3,000 7 Inch Lead-free version is RoHS/WEEE Compliant Contact Information Semtech Corporation Protection Products Division 200 Flynn Rd., Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804 2006 Semtech Corp. 6 www.semtech.com