RClamp0554S RailClamp Low Capacitance TVS Diode Array

Transcription

1 - RailClamp Description RailClamp is a low capacitance TVS array designed to protect high speed data interfaces. This series has been specifically designed to protect sensitive components which are connected to data and transmission lines from overvoltage caused by electrostatic discharge (ESD), electrical fast transients (EFT), and lightning. The unique design incorporates eight surge rated, low capacitance steering diodes and a TVS diode in a single package. During transient conditions, the steering diodes direct the transient to either the positive side of the power supply line or to ground. The internal TVS diode prevents over-voltage on the power line, protecting any downstream components. The RClamp 554S is in a 6-lead SOT-2 package. The leads are finished with lead-free matte tin. Each device will protect up to four high-speed lines. They may be used to meet the ESD iunity requirements of IEC 6-4-2, Level 4 (5kV air, 8kV contact discharge). The combination of small size, low capacitance, and high surge capability makes them ideal for use in applications such as Ethernet, USB 2., and video interfaces. RClamp554S RailClamp Low Capacitance TVS Diode rray Features ESD protection for high-speed data lines to IEC (ESD) ±5kV (air), ±8kV (contact) IEC (EFT) 4 (5/5ns) IEC (Lightning) 25 (8/2μs) rray of surge rated diodes with internal TVS Diode Small package saves board space Protects four I/O lines and Voltage Bus Low capacitance: 5pF (VR=V) Low clamping voltage Low operating voltage: 5.V Solid-state silicon-avalanche technology Mechanical Characteristics JEDEC SOT-2 6L package Pb-Free, Halogen Free, RoHS/WEEE Compliant Molding compound flaability rating: UL 94V- Marking : Marking code + date code Packaging : Tape and Reel pplications USB 2. Power and Data Line Protection // Ethernet Video Graphics Cards Monitors and Flat Panel Displays Digital Video Interface (DVI) Notebook Computers IEEE 94 Firewire Ports Circuit Diagram Schematic and PIN Configuration SOT-2 6L (Top View) Revision /7/2

2 bsolute Maximum Rating Rating Symbol Value Units Peak Peak Pulse Power (tp = 8/2μs) Pulse Current (tp = 8/2μs) P pk 75 Watts I PP 25 ESD per IEC ESD per IEC (ir) (Contact) VESD +/- +/- 25 kv Operating Temperature T J -55 to +25 C Storage Temperature T STG 55 to +5 - C Electrical Characteristics (T=25 o C) Parameter Symbol Conditions Minimum Typical Maximum Units Reverse Stand-Off Voltage V RWM 5 V Reverse Breakdown Voltage B I t = m 6 V V R Reverse Leakage Current I R V RWM = 5V, T=25 C. 5 μ Clamping Voltage I PP =, tp = 8/2μs ny I/O to GND Clamping Voltage I PP =, tp = 8/2μs ny I/O to GND Clamping Voltage I PP = 25, tp = 8/2μs ny I/O to GND Junction Capacitance C j ny I/O to GND = V, f = V R V R I/O to I/O = V, f = 9.8 V 2 V 5 V 5 pf pf 2 Semtech Corp. 2

3 Typical Characteristics Non-Repetitive Peak Pulse Power vs. Pulse Time Power Derating Curve Peak Pulse Power - P PP (kw).. Pulse Duration - tp ( s) Pulse Waveform % of Rated Power or IPP mbient Temperature - T ( o C) Clamping Voltage vs. Peak Pulse Current Percent of IPP e -t td = IPP/2 Waveform Parameters: tr = 8µs td = 2µs Time (µs) Clamping Voltage - (V) Peak Pulse Current - I PP () Waveform Parameters: tr = 8µs td = 2µs Forward Voltage vs. Forward Current Normalized Capacitance vs. Reverse Voltage 9.2 Forward Voltage - Vf (V) Peak Pulse Current - Ipp () Waveform Parameters: tr = 8µs td = 2µs Cj(VR) / Cj(VR=V) f = Reverse Voltage (VR) - V 2 Semtech Corp.

4 pplications Information Insertion Loss S2 - ny I/O to GND Insertion Loss S2 - I/O to I/O CH S2 LOG 6 db / REF db CH S2 LOG 6 db / REF db : db 8 : db 8 db 2: db 9 db 2: db 9-6 db -2 db -8 db : db.8 GHz 4: db 2.5 GHz -6 db -2 db -8 db : db.8 GHz 4: db 2.5 GHz -24 db -24 db - db - db -6 db -6 db -42 db -42 db -48 db GHz GHz -48 db GHz GHz STRT. STOP. STRT. STOP. ESD Clamping - Between any I/O and GND (+8kontact per IEC 6-4-2) ESD Clamping - Between any I/O and GND (-8kontact per IEC 6-4-2) Note: Data is taken with a x attenuator Note: Data is taken with a x attenuator 2 Semtech Corp. 4

5 pplications Information Device Connection Options for Protection of Four High-Speed Data Lines The RClamp554S 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,, 4 and 6. The negative reference (REF) 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:. To protect data lines and the power line, connect pin 5 directly to the positive supply rail (C ). 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 RClamp554S can be isolated from the power supply by adding a series resistor between pin 5 and C. value of kω is recoended. The internal TVS and steering diodes remain biased, providing the advantage of lower capacitance.. 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). 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 ESD Protection With RailClamps RailClamps are optimized for ESD protection using the rail-to-rail topology. long with good board layout, these devices virtually eliminate the disadvantages of using discrete components to implement this topology. Consider the situation shown in Figure where discrete diodes or diode arrays are configured for rail-torail 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 2 Semtech Corp. 5

6 pplications Information (continued) the reference voltage plus the V F drop of the diode. For negative events, the bottom diode will be biased when the voltage exceeds the V F of the diode. t first approximation, the clamping voltage due to the characteristics of the protection diodes is given by: PIN Descriptions = C + V F = -V F (for positive duration pulses) (for negative duration pulses) However, for fast rise time transient events, the effects of parasitic inductance must also be considered as shown in Figure 2. Therefore, the actual clamping voltage seen by the protected circuit will be: = C + V F + L P di ESD /dt (for positive duration pulses) = -V F - L G di ESD /dt (for negative duration pulses) Figure - Rail-To-Rail Protection Topology (First pproximation) ESD current reaches a peak amplitude of in ns for a level 4 ESD contact discharge per IEC Therefore, the voltage overshoot due to nh of series inductance is: V = L P di ESD /dt = X -9 ( / X -9 ) = V Example: Consider a C = 5V, a typical V F of V (at ) for the steering diode and a series trace inductance of nh. The clamping voltage seen by the protected IC for a positive 8kV () ESD pulse will be: = 5V + V + (nh X V/nH) = 5V This does not take into account that the ESD current is directed into the supply rail, potentially damaging any components that are attached to that rail. lso note that it is not uncoon for the V F of discrete diodes to exceed the damage threshold of the protected IC. This is due to the relatively small junction area of typical discrete components. It is also possible that the power dissipation capability of the discrete diode will be exceeded, thus destroying the device. The RailClamp is designed to overcome the inherent disadvantages of using discrete signal diodes for ESD suppression. The RailClamp s integrated TVS diode Figure 2 - The Effects of Parasitic Inductance When Using Discrete Components to Implement Rail-To-Rail Protection Figure - Rail-To-Rail Protection Using RailClamp TVS rrays 2 Semtech Corp. 6

7 pplications Information (continued) helps to mitigate the effects of parasitic inductance in the power supply connection. During an ESD event, the current will be directed through the integrated TVS diode to ground. The maximum voltage seen by the protected IC due to this path will be the clamping voltage of the device. RClamp554S Universal Serial Bus ESD Protection The RClamp554S may also be used to protect the USB ports on monitors, computers, peripherals or portable systems. Each device will protect up to two USB ports (Figure 4). When the voltage on the data lines exceed the bus voltage (plus one diode drop), the internal rectifiers are forward biased conducting the transient current away from the protected controller chip. The TVS diode directs the surge to ground. The TVS diode also acts to suppress ESD strikes directly on the voltage bus. Thus, both power and data pins are protected with a single device. Figure 4 - Dual USB Port Protection 2 Semtech Corp. 7

8 Outline Drawing -SOT2 - SO-8 6L 2X E/2 ccc C 2X N/2 TIPS aaa C SETING PLNE C N 2 B D SIDE VIEW e bxn bbb e EI 2 D E C -B D SEE DETIL DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MX MIN NOM MX b c D E E e. BSC.7 BSC 2.8 BSC.95 BSC e.75 BSC.9 BSC L L (.24) (.6) N aaa.4. bbb.8.2 ccc.8.2 GGE PLNE.25 H DETIL L (L) c NOTES:. CONTROLLING DIMENSIONS RE IN MILLIMETERS (NGLES IN DEGREES). 2. DTUMS -- ND -B- TO BE DETERMINED T DTUM PLNE -H-. DIMENSIONS "E" ND "D" DO NOT INCLUDE MOLD FLSH, PROTRUSIONS OR GTE BURRS. Land Pattern -SOT2 6L X (C) P G Y Z DIM C G P X Y Z DIMENSIONS INCHES MILLIMETERS (.98) (2.5) NOTES:. THIS LND PTTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MNUFCTURING GROUP TO ENSURE YOUR COMPNY'S MNUFCTURING GUIDELINES RE MET. 2 Semtech Corp. 8

9 Marking Codes Ordering Information V54 YW Part Number RClamp554S.TCT Lead Finish Qty per Reel Reel Size Matte Tin, 7 Inch YW = 2 - lphanumeric characters for Date Code Tape and Reel Specification Pin Location User Direction of feed B K.2 +/ / /-.5 Tape Width B, (Max) D D E F K (MX) P P P 2 T(MX) W (.65) ±.5.75±..5± ±. 4.±. 2.± Contact Information Semtech Corporation Protection Products Division 2 Flynn Road, Camarillo, C 92 Phone: (85)498-2 FX (85) Semtech Corp. 9