USB6Bx ® Application Specific Discretes A.S.D. DATA LINES PROTECTION APPLICATIONS Where transient overvoltage protection in sensitive equipment is required, such as: - Universal Serial Bus ports - RS-423 interfaces - RS-485 interfaces - ISDN equipment - T1/E1 line cards - HDSL / ASDL interfaces SO8 FEATURES n Full diode bridge with integrated clamping protection n Breakdown voltage : VBR = 6V min. n Peak pulse power dissipation : PPP = 500W (8/20µs) n Very low capacitance, compatible with high debit data or signal rates. DESCRIPTION In order to prevent fast transients from leading to severe damages in a high speed data system, a specific protection has been developed by STMicroelectronics. The USB6Bx protects the two input lines against overvoltage. Besides, this device also keeps the power rails in a safe limit thanks to the integrated Transil diode. DIL8 BENEFITS n n n n Provides protection for each line and between the supply voltage and GND : 25A , 8/20µs. High ESD protection level : up to level 3 per MIL STD 883C-Method 3015-6 Separated inputs and outputs (so-called 4-point structure) to improve ESD susceptibility. Comprehensive package pin-out for immediate implementation. FUNCTIONAL DIAGRAM COMPLIES WITH THE FOLLOWING STANDARDS: Vcc Vcc MIL STD 883C - Method 3015-6 class 3 C = 100 pF R = 1500 Ω 3 positive strikes and 3 negative strikes (F = 1 Hz) IEC-1000-4-2 level 4 15 kV (air discharge) 8 kV (contact discharge) I/01 I/01 I/02 I/02 GND GND TM: ASD and TRANSIL are trademarks of ST Microelectronics. August 1999 Ed : 5A 1/9 USB6Bx TECHNICAL INFORMATION SURGE PROTECTION The USB6Bx is particularly optimized to perform surge protection based on the rail to rail topology. The clamping voltage VCL can be estimated as follow: VCL+ =Vcc + VF for positive surges for negative surges VCL - = - VF with: VF = Vt + rd.Ip (VF forward drop voltage) / (Vt forward drop threshold voltage) Note: the estimations do not take into account phenomena due to parasitic inductances. Fig. A1 : Lw ESD SURGE +Vcc Vf Lw di dt I/O di Vcl+ = Vcc+Vf+ Lw dt surge >0 VI/O Vcl- = Lw di dt -Vf- Lw di dt surge <0 GND tr=1ns Vcl+ t -Vf Lw di dt POSITIVE SURGE -Lw NEGATIVE SURGE di dt Vcc+Vf t Vcltr=1ns 2/9 USB6Bx HOW TO ENSURE A GOOD ESD PROTECTION While the USB6Bx provides a high immunity to ESD surge, an efficient protection depends on the layout of the board. In the same way, with the rail to rail topology, the track from the VCC pin to the power supply and from the GND pin to GND voltage must be as short as possible to avoid overvoltages due to parasitic phenomena (see Fig A1). It’s often harder to connect the power supply near to the USB6Bx unlike the ground thanks to the ground plane that allows a short connection. Fig. A2: ESD behavior: optimized layout and add of a capacitance of 100nF. Lw ESD SURGE REF2=+Vcc C=100nF I/O VI/O Vcl+ = Vcc+Vf surge >0 Vcl- = surge <0 -Vf REF1=GND To ensure the same efficiency for positive surges when the connections can’t be short enough, we recommend to put close to the USB6Bx between VCC and ground, a capacitance of 100nF to prevent from these kinds of overvoltage disturbances (see Fig. A2 ). The add of this capacitance will allow a better protection by providing during surge a constant voltage. Fig. A3 shows the improvement of the ESD protection according to the recommendations described above. Vcl+ t NEGATIVE SURGE POSITIVE SURGE t Vcl- IMPORTANT: A main precaution to take is to put the protection device closer to the disturbance source (generally the connection). 3/9 USB6Bx TECHNICAL INFORMATION Universal Serial Bus. The new data transmission standard, Universal Serial Bus (USB) is being driven by market leaders in the world of Computer and Telecommunications, including Compaq, DEC, IBM, Intel, Microsoft, NEC and Nortel, and will become the leading transmission protocol within the next few years. This standard mainly provides simplified interconnectivity. Specialized ports on the back of the present PC will largely be replaced by USB ports. Many peripherals such as printers, keyboards, monitors and joysticks will also host USB ports. The USB offers high speed communication rates up to 12 Mbit/s. Only two wires (D+, D-) are required for data transfer. Additionally, limited amount of power for USB devices located on the downstream can also be transmitted on two separate conductors within the same cable. Protection to support USB. Designers dealing with the USB chips are concerned about electrostatic discharge sensitivity (ESD) of their USB controller ICs. The USB controller is more than just a driver / receiver; it acts as a microcontroller which manages power and direct signal traffic. This complexity increases its cost over conventional devices. Therefore, a failure of a USB port could result in costly computer failure. In order to prevent these fast transients from leading to severe damages in a system, a specific protection has been developed by STMicroelectronics. The USB6Bx protects not only the two wires of data transmission, but also keep the power rails in a safe limit. Fig. A3: recommended configuration for USB port protection. Vbus 1 D+ USB IC DGND USB output connector The capacitance between the I/O transmission wires provides no significant signal distortion at the 12 Mbit/s data rate, thus allowing full compatibility with USB standard. 4/9 Available either in a compact SO8 or in a through-hole DIL8 package, this protective element requires minimal board space and eases the PCB layout thanks to its direct compatibility with the USB connector pin-out. USB6Bx TELECOM AND DATACOM APPLICATIONS ISDN U interface protection. 3* SMP100 USB6Bx +Vcc LT DC Power Source T1 / E1 Line Card Protection. RTIP USB6B1 SMP75-8 or SMP100-8 +Vcc RRING TTIP +Vcc TRING SMP75-8 or SMP100-8 USB6B1 High Speed Line Driver / Receiver Protection. +5V +5V SM6T6V8A +Vcc +Vcc INPUT SM6T6V8A DRIVER USB6B1 RECEIVER OUTPUT USB6B1 5/9 USB6Bx ABSOLUTE MAXIMUM RATINGS (Tamb = 25°C) Symbol Parameter Value Unit VPP Peak pulse voltage IEC1000-4-2 contact discharge IEC1000-4-2 air discharge MIL STD883C-Method 3015-6 8 15 4 kV PPP Peak pulse power 8/20 µs 500 W IPP Peak pulse current 8/20 µs 25 A Tstg Tj Storage temperature range Maximum junction temperature - 55 to + 150 + 150 °C °C TL Lead solder temperature (10s duration) 260 °C ELECTRICAL CHARACTERISTICS (Tamb = 25°C) Value Symbol Parameter Unit min. VBR Breakdown voltage between Vbus and GND IRM Leakage current C Capacitance between pins D+ and DVOSC =30mV, F=1MHz, VR=0V Capacitance between pins D+ (or D-) and GND VOSC =30mV, F=1MHz, VR=5V 6/9 IR=1mA typ. max. 6 V VRM=5.25V 10 µA VCC not connected 15 pF VCC=5V 25 pF USB6Bx Fig 1: Peak power dissipation versus initial junction temperature. Ppp[Tj initial]/Ppp[Tj initial=25°C] 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Tj initial(°C) 0.0 -40 -20 0 20 40 60 80 100 120 140 160 Fig 2: Relative variation of leakage current versus junction temperature (typical values). 10.0 IR[Tj] / IR[Tj=25°C] 1.0 Tj(°C) 0.1 -40 -20 0 20 40 60 80 100 120 140 Fig 3: Relative variation of breakdown voltage versus junction temperature (typical values). 1.10 VBR[Tj] / VBR[Tj=25°C] 1.05 1.00 0.95 0.90 -40 -20 Tj(°C) 0 20 40 60 80 100 120 140 7/9 USB6Bx ORDER CODE USB 6 B1 RL PACKAGING: RL = tape and reel.(SO8 only) = tube PACKAGE: 1 = SO8 2 = DIL8 VBR min PACKAGE MECHANICAL DATA. SO8 Plastic DIMENSIONS REF. Millimetres Min. c1 a1 C a3 a2 0.1 a2 a1 S E e3 D M b1 5 F 1 8/9 4 Typ. Max. 1.75 0.069 0.25 0.004 0.010 1.65 0.065 a3 0.65 0.85 0.025 0.033 b 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 C 0.25 0.50 0.010 0.020 0.50 c1 8 Min. A e b Typ. Max. A L Inches 45° (typ) D 4.8 E 5.8 5.0 0.189 6.2 0.228 0.197 0.244 e 1.27 0.050 e3 3.81 0.150 F 3.8 4.0 0.15 0.157 L 0.4 1.27 0.016 0.050 M 0.6 0.024 S 8⊃ (max) USB6Bx PACKAGE MECHANICAL DATA. DIL8 Plastic DIMENSIONS REF. b1 L F a1 0.51 B 0.85 b e B 0.020 1.40 0.033 0.5 b1 b 0.38 D e3 D Z 8 E Z E 5 1 Inches Min. Typ. Max. Min. Typ. Max. I a1 Millimetres 4 8.10 8.80 0.055 0.020 0.50 0.015 0.020 10.15 0.399 9.40 0.319 0.346 0.370 e 2.54 0.100 e3 7.62 0.300 F 7.1 0.280 I 5.1 0.200 L 3.3 Z 0.130 1.50 0.063 MARKING Types Package Weight Marking ORDER CODE Base Qty USB6B1 SO8 0.077g USB62 USB6B1 100 pcs (tube) USB6B1RL 2500 pcs (tape and reel) USB6B2 50 pcs (tube) USB6B2 DIL8 0.59g USB62 - Epoxy meets UL94, V0 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics © 1999 STMicroelectronics - Printed in Italy - All rights reserved. STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com 9/9