SRDA70-4 RailClampÒ Low Capacitance TVS Diode Array PROTECTION PRODUCTS Description Features u Transient protection for high speed data lines to RailClamps are surge rated diode arrays designed to protect high speed data interfaces. The SRDA70-4 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 unique design of the SRDA70-4 integrates eight surge rated, low capacitance steering diodes in a low profile SO-8 package. During transient conditions, the steering diodes direct the transient to either the positive side of the power supply line or to ground. The SRDA70-4 may be used as a stand alone device or in conjunction with TVS diodes for enhanced protection. The low capacitance array configuration allows the user to protect four high speed data or I/O lines. The low inductance construction minimizes voltage overshoot during high current surges. u u u u u u 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 diodes Protects four I/O lines Low capacitance for high-speed interfaces High surge capability Low forward voltage characteristics Solid-state silicon avalanche technology Mechanical Characteristics u u u u u JEDEC SO-8 package UL 497B listed Molding compound flammability rating: UL 94V-0 Marking : Part number, date code, logo Packaging : Tube or Tape and Reel per EIA 481 Applications u u u u u u u Circuit Diagram Latch-Up Protection Microcontroller Input Protection Token Ring I2C Bus Protection Video Line Protection Set Top Box I/O LAN/WAN Equipment Schematic & PIN Configuration I/O 1 REF 1 I/O 1 I/O 2 I/O 3 REF 2 REF 1 I/O 4 REF 1 I/O 3 I/O 4 I/O 2 REF 2 REF 2 SO-8 (Top View) Revision 9/2000 1 www.semtech.com SRDA70-4 PROTECTION PRODUCTS Absolute Maximum Rating R ating Symbo l Value Units I PP 24 A Rectifier Rep etitive Peak Reverse Voltage V RRM 70 V Th ermal Resistance, Junction to A mb ient qJA 163 °C /W Th ermal Resistance, Junction to Case qJC 38.8 °C /W Lead Sold ering Temp erature TL 260 (10 sec.) °C Op erating Temp erature TJ -55 to +125 °C TSTG -55 to +150 °C Peak Pulse Current (tp = 8/20µ s) Storage Temp erature Electrical Characteristics SR DA70-4 Par ame te r Symbo l Co nd itio ns Rectifier Rep etitive Peak reverse Voltage V RRM Reverse Breakd ow n Voltage V BR It = 50µ A Reverse Leakage Current IR V RWM = 70V, T=25°C 5 µA Forw ard Voltage VF IPP = 1A , tp = 8/20µ s 1.3 V Forw ard Voltage VF IPP = 10A , tp = 8/20µ s 3.3 V Junction Cap acitance Cj Betw een I/O p ins and Gnd V R = 0V, f = 1MHz 15 pF Betw een I/O p ins V R = 0V, f = 1MHz ã 2000 Semtech Corp. 2 Minimum Typ ical Maximum Units 70 V 85 V 4 pF www.semtech.com SRDA70-4 PROTECTION PRODUCTS Typical Characteristics Non-Repetitive Peak Pulse Power vs. Pulse Time Power Derating Curve 10 110 90 % of Rated Power or IPP Peak Pulse Power - P PP (kW) 100 1 0.1 80 70 60 50 40 30 20 10 0 0.01 0.1 1 10 100 0 1000 25 Pulse Waveform 75 100 125 150 Variation of Capacitance vs. Reverse Voltage 110 0 Waveform Parameters: tr = 8µs td = 20µs 90 80 70 e 60 -t 50 40 I/O to GND f = 1MHz -2 % Change in Capacitance 100 Percent of IPP 50 Ambient Temperature - TA (oC) Pulse Duration - tp (µs) td = IPP/2 30 20 -4 -6 -8 -10 -12 -14 10 0 -16 0 5 10 15 20 25 30 0 Time (µs) 1 2 3 4 5 6 Reverse Voltage (V) Foward 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) ã 2000 Semtech Corp. 3 www.semtech.com SRDA70-4 PROTECTION PRODUCTS Applications Information I/O Protection Device Connection Options for Protection of Four High-Speed Data Lines The SRDA70-4 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 VF) the steering diodes are forward biased, conducting the transient current away from the sensitive circuitry. Data lines are connected at pins 1, 4, 6 and 7. The negative reference (REF2) is connected at pins 5 & 8. These pins 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 (REF1) is connected at pins 2 & 3. The options for connecting the positive reference are as follows: Microcontroller Protection 1. To protect data lines and the power line, connect pins 2 & 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. The SRDA70-4 can be isolated from the power supply by adding a series resistor between pins 2 & 3 and VCC. A value of 10kW is recommended. The internal 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, 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). ã 2000 Semtech Corp. SRDA70-4 4 www.semtech.com SRDA70-4 PROTECTION PRODUCTS Outline Drawing - SO-8 Land Pattern - SO-8 ã 2000 Semtech Corp. 5 www.semtech.com SRDA70-4 PROTECTION PRODUCTS Ordering Information Par t Numbe r Qty p e r Reel R e e l Size SRDA 70-4.TB 500 7 Inch SRDA 70-4.TE 2500 13 Inch Contact Information Semtech Corporation Protection Products Division 652 Mitchell Rd., Newbury Park, CA 91320 Phone: (805)498-2111 FAX (805)498-3804 ã 2000 Semtech Corp. 6 www.semtech.com