USB6B1 Data line 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 SO-8 Order Codes Features ■ Full diode bridge with integrated clamping protection ■ Breakdown voltage: VBR = 6 V min. ■ Peak pulse power dissipation: PPP = 500 W (8/20 µs) ■ Very low capacitance, compatible with high debit data or signal rates. Part Numbers Marking USB6B1 USB62 USB6B1RL USB62 Functional diagram 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. VCC VCC I/O1 I/O1 I/O2 I/O2 GND GND The USB6B1 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. Complies with the following standards: Benefits MIL STD 883C - Method 3015-6 ■ Provides protection for each line and between the supply voltage and GND: 25 A, 8/20 µs. ■ 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. August 2006 class 3 C = 100 pF R = 1500 Ω 3 positive strikes and 3 negative strikes (F = 1 Hz) IEC 61000-4-2 level 4 15 kV (air discharge) 8 kV (contact discharge) Rev 10 1/9 www.st.com 9 Characteristics 1 USB6B1 Characteristics Table 1. Absolute maximum ratings Symbol Parameter Value Unit VPP Peak pulse voltage IEC61000-4-2 contact discharge IEC61000-4-2 air discharge MIL STD883C-Method 30 15-6 8 15 4 kV PPP Peak pulse power 8/20 µs 500 W 8/20 µs 25 IPP Peak pulse current 2/10 µs 40 Tstg Top Storage temperature range Operating temperature range TL Table 2. A - 55 to + 150 - 40 to + 85 °C °C 260 °C Lead solder temperature (10 s duration) Electrical characteristics (Tamb = 25° C) Value Symbol Parameter Unit Min Typ Max VBR Breakdown voltage between VBUS and GND IR = 1 mA IRM Leakage current VRM = 5.25 V Capacitance between pins D+ and DVOSC = 30 mV, F = 1 MHz, VR = 0 V VCC not connected C Capacitance between pins D+(or D-) and GND VCC = 5 V VOSC = 30 mV, F = 1 MHz, VR = 5 V 2/9 6 V 10 µA 15 pF 25 pF USB6B1 Characteristics Figure 1. Peak power dissipation versus initial junction temperature Figure 2. Ppp[Tj initial]/Ppp[Tj initial=25°C] Relative variation of leakage current versus junction temperature (typical values) IR[Tj] / IR[Tj=25°C] 10.0 1.1 1.0 0.9 0.8 0.7 0.6 1.0 0.5 0.4 0.3 0.2 0.1 Tj initial(°C) Tj(°C) 0.1 0.0 -40 -20 Figure 3. 1.10 0 20 40 60 80 100 120 140 160 -40 -20 0 20 40 60 80 100 120 140 Relative variation of breakdown voltage versus junction temperature (typical values) VBR[Tj] / VBR[Tj=25°C] 1.05 1.00 0.95 Tj(°C) 0.90 -40 -20 0 20 40 60 80 100 120 140 3/9 Technical information USB6B1 2 Technical information 2.1 Surge protection The USB6B1 is 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 VCL - = - VF for negative surges 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. Figure 4. Surge behavior Figure 5. Lw ESD SURGE Lw ESD SURGE +Vcc Vf ESD behavior: optimized layout and addition of a 100 nF capacitor Lw di dt REF2=+Vcc C=100nF I/O I/O di Vcl+ = Vcc+Vf+Lw dt surge >0 di surge <0 Vcl- = -Vf- Lw dt VI/O Lw di dt VI/O Vcl+ = Vcc+Vf surge >0 Vcl- = surge <0 -Vf REF1=GND GND tr=1ns Vcl+ t Vcl+ t -Vf Lw di dt POSITIVE SURGE -Lw NEGATIVE SURGE di dt NEGATIVE SURGE POSITIVE SURGE Vcc+Vf t Vcltr=1ns 2.2 t Vcl- How to ensure good ESD protection While the USB6B1 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 Figure 4.) It’s often harder to connect the power supply near to the USB6B1 unlike the ground thanks to the ground plane that allows a short connection. To ensure the same efficiency for positive surges when the connections can’t be short enough, we recommend to putting a 100 nF c apacitor close to the USB6B1 between VCC and ground to prevvent these kinds of overvoltage disturbances (see Figure 5.) The addition of this capacitor offers better protection by providing a constant voltage during the surge. Figure 6. shows the improvement of the ESD protection according to the recommendations described above. Important: An imortant precaution to take is to put the protection device closer to the disturbance source (generally the connection). 4/9 USB6B1 2.3 Technical information Universal Serial Bus The 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 has become a leading transmission protocol. 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, key-boards, monitors and joysticks use USB ports. The USB offers high speed communication rates up to 480 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. 2.4 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. Figure 6. Recommended configuration for USB port protection VBUS D+ D- 1 USB IC GND 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 compatibility with USB standard. Available in a compact SO-8 this protective element requires minimal board space and eases the PCB layout thanks to its direct compatibility with the USB connector pin-out. 5/9 Telecom and datacom applications 3 USB6B1 Telecom and datacom applications Figure 7. ISDN U interface protection 3* SMP100 USB6Bx +Vcc LT DC Power Source Figure 8. T1 / E1 Line Card Protection. RTIP USB6B1 SMP75-8 or SMP100-8 +Vcc RRING TTIP +Vcc TRING SMP75-8 or SMP100-8 USB6B1 Figure 9. High Speed Line Driver / Receiver Protection +5V +5V SM6T6V8A DRIVER USB6B1 6/9 +Vcc +Vcc INPUT SM6T6V8A USB6B1 RECEIVER OUTPUT USB6B1 4 Ordering information scheme Ordering information scheme USB 6 B1 RL USB Protection Breakdown voltage 6 = 6V min. Package B1 = SO-8 Packaging RL = Tape & reel Blank = Tube 5 Package information Epoxy meets UL94, V0 Table 3. SO-8 dimensions Dimensions Ref. Millimeters Min. Typ. A C (Seating Plane) ccc C A2 0.25mm (Gage Plane) C L A1 e b A h x 45° k Inches Max. Min. Typ. 1.75 A1 0.1 0.25 A2 1.25 b 0.28 C 0.17 D 4.80 4.90 E 5.80 E1 3.80 Max. 0.069 0.004 0.010 0.049 0.48 0.011 0.019 0.23 0.007 0.009 5.00 0.189 0.193 0.197 6.00 6.20 0.228 0.236 0.244 3.90 4.00 0.150 0.154 0.157 L1 D 8 5 E1 E e 1 1.27 0.050 4 h 0.25 0.50 0.010 0.020 L 0.40 1.27 0.016 0.050 L1 k° ccc 1.04 0 0.041 8 0.10 0 8 0.004 7/9 Ordering information USB6B1 Figure 10. SO-8 footprint (dimensions in mm) 6.8 0.6 4.2 1.27 In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at: www.st.com. 6 Ordering information Ordering code Marking USB6B1 USB62 USB6B1RL 7 8/9 Package Weight SO-8 0.077 g USB62 Base qty Delivery mode 100 Tube 2500 Tape and reel Revision history Date Revision Description of Changes Oct-2003 6A 03-May-2005 7 Figure 1 on page 1: dots connection corrected. 22-Feb-2006 8 Marking typing error corrected on page 1 and 7. 16-Aug-2006 9 Reformated to current standard. ECOPACK statement added. SO-8 package dimensions corrected. Previous issue. 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