SR70

PROTECTION PRODUCTS Description 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 ESD (electrostatic discharge), EFT (electrical fast transients), 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. RailClamp Low Capacitance TVS Diode Array Features 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 SR70 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 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 Circuit Diagram Schematic & PIN Configuration Pin 4 1 Pin 2 Pin 3 4 2 Pin 1 3 SOT-143 (Top View) Revision 04/18/03 1 www.semtech.com SR70 PROTECTION PRODUCTS Absolute Maximum Rating R ating Peak Pulse Current (tp = 8/20µs) Rectifier Repetitive Peak Reverse Voltage ESD per IEC 61000-4-2 (Air) ESD per IEC 61000-4-2 (Contact) Lead Soldering Temperature Operating Temperature Storage Temperature Symbol IP P V RRM VESD TL TJ TSTG Value 24 70 15 8 260 (10 sec.) -55 to +125 -55 to +150 Units A V kV °C °C °C Electrical Characteristics (T=25oC) SR70 Parameter Peak Reverse Stand-Of f Voltage Reverse Breakdown Voltage Reverse Leakage Current Forward Clamping Voltage Forward Clamping Voltage Forward Clamping Voltage Junction Capacitance Symbol VRRM VBR IR VFC VFC VFC Cj It = 50µA VRWM = 70V, T=25°C IPP = 1A, tp = 8/20µs IPP = 10A, tp = 8/20µs IPP = 24A, tp = 8/20µs Between I/O pins and Ground VR = 0V, f = 1MHz Between I/O pins VR = 0V, f = 1MHz 5 85 5 1.5 3.3 7 10 Conditions Minimum Typical Maximum 70 Units V V µA V V V pF 3 pF  2003 Semtech Corp. 2 www.semtech.com SR70 PROTECTION PRODUCTS Typical Characteristics Non-Repetitive Peak Pulse Power vs. Pulse Time 10 Peak Pulse Power - PPk (kW) Power Derating Curve 110 100 % of Rated Power or PP I 90 80 70 60 50 40 30 20 10 0 1 0.1 0.01 0.1 1 10 Pulse Duration - tp (µs) 100 1000 0 25 50 75 100 125 150 Ambient Temperature - TA (oC) Pulse Waveform 110 100 90 80 Percent of IPP 70 60 50 40 30 20 10 0 0 5 10 15 Time (µs) 20 25 30 td = IPP/2 e -t Capacitance vs. Reverse Voltage Waveform Parameters: tr = 8µs td = 20µs 0 -2 % Change in Capacitance -4 -6 -8 -10 -12 -14 -16 0 1 2 3 4 5 6 Reverse Voltage - VR (V) I/O to GND f = 1MHz Forward Voltage vs. Forward Current 10 9 Forward Voltage - V F (V) 8 7 6 5 4 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 Forward Current - IF (A) Waveform Parameters: tr = 8µs td = 20µs  2003 Semtech Corp. 3 www.semtech.com SR70 PROTECTION PRODUCTS Applications Information 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. 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). SR70 Pin Configuration 1 4 2 3 Data Line and Power Supply Protection Using Vcc as reference  2003 Semtech Corp. 4 www.semtech.com SR70 PROTECTION PRODUCTS Outline Drawing Notes: (1) Controlling dimension: Inch (unless otherwise specified). (2) Dimension A and B do not include mold protrusions. Mold protrusions are .006” max. Land Pattern  2003 Semtech Corp. 5 www.semtech.com SR70 PROTECTION PRODUCTS Marking Codes Part Number SR70 Marking Code R70 R70 SR70 Marking (Top View) Ordering Information Par t Number SR70.TC SR70.TG Qty per Reel 3,000 10,000 R eel Size 7 Inch 13 Inch Contact Information Semtech Corporation Protection Products Division 200 Flynn Rd., Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804  2003 Semtech Corp. 6 www.semtech.com