USBUF01P6

USBUF01P6 IPAD™ EMI filter and line termination for USB upstream ports Applications EMI Filter and line termination for USB upstream ports on: ■ ■ USB Hubs PC peripherals Features ■ ■ ■ ■ Monolithic device with recommended line termination for USB upstream ports Integrated Rt series termination and Ct bypassing capacitors. Integrated ESD protection Small package size SOT-666IP (Internal pad) Functional diagram 3.3 V Rt D1 Ct Rp D4 Description The USB specification requires upstream ports to be terminated with pull-up resistors from the D+ and D- lines to Vbus. On the implementation of USB systems, the radiated and conducted EMI should be kept within the required levels as stated by the FCC regulations. In addition to the requirements of termination and EMC compatibility, the computing devices are required to be tested for ESD susceptibility. The USBUF01P6 provides the recommended line termination while implementing a low pass filter to limit EMI levels and providing ESD protection which exceeds IEC 61000-4-2 level 4 standard. The device is packaged in a SOT-666 which is the smallest available lead frame package (45% smaller than the standard SOT323). Grd 3.3 V Rt D2 Ct D3 Complies with the following standards: IEC 61000-4-2 level4: 15 kV(air discharge) 8 kV(contact discharge) MIL STD 883E-Method 3015-7: Class 3 C = 100 pF R = 1500 Ω 3 positive strikes and 3 negative strikes (F = 1 Hz) Benefits ■ ■ ■ ■ ■ EMI / RFI noise suppression Required line termination for USB upstream ports ESD protection exceeding IEC 61000-4-2 level 4 High flexibility in the design of high density boards Tailored to meet USB 2.0 standard (low speed and full speed data transmission) Order codes Part Number USBUF01P6 Marking U TM: IPAD is a trademeark of STMicroelectronics August 2006 Rev 6 1/9 www.st.com 9 Characteristics USBUF01P6 1 Characteristics Table 1. Symbol Absolute maximum rating (Tamb = 25° C) Parameter IEC61000-4-2 air discharge IEC61000-4-2 contact discharge MIL STD 883E - Method 3015-7 Value ± 16 ±9 ± 25 150 -55 to +150 260 -40 to + 85 Unit VPP Tj Tstg TL Top ESD discharge Junction temperature Storage temperature range kV °C °C °C °C Maximum lead temperature for soldering during 10 s at 5 mm for case Operating temperature range Table 2. Symbol VRM VBR VCL IRM IPP αT VF Rd Electrical characteristics (Tamb = 25° C) Parameter Stand-off voltage Breakdown voltage Clamping voltage Leakage current Peak pulse current Voltage temperature coefficient Forward voltage drop Dynamic resistance Slope = 1/Rd I IF VCL VBR VRM IRM VF V IPP Symbol VBR IRM Rt Rp Ct Test conditions IR = 1 mA VRM = 3.3 V per line Tolerance ± 10% Tolerance ± 10% Tolerance ± 20% Min. 6 Typ. Max. 10 500 Unit V nA Ω kΩ pF 33 1.5 47 2/9 USBUF01P6 Technical information 2 Technical information Figure 1. USB Standard requirements. 3.3V 1.5k Rt D+ Twisted pair shielded D+ Rt Ct Rt Full-speed or Low-speed USB Transceiver Ct Rt Full-speed USB Transceiver DHost or Hub port Ct 15k 15k Zo = 90ohms 5m max DCt Hub 0 or Full-speed function FULL SPEED CONNECTION 3.3V 1.5k Rt D+ Untwisted unshielded D+ Rt Ct Rt Full-speed or Low-speed USB Transceiver Ct Rt Low-speed USB Transceiver DHost or Hub port Ct 15k 15k 3m max DCt Hub 0 or Low-speed function LOW SPEED CONNECTION 2.1 Application example Figure 2. Implementation of ST solutions for USB ports. USBDF01W5 Rt D+ in Ct Rd D+ out Downstream port Host/Hub USB por transceivert USBUF01W6 D2 Gnd D1 Upstream port D+ Peripheral transceiver D+ D+ CABLE D+ Ct Rt Ct Rt 3.3 V Rp Gnd Gnd Ct Rd D- in Rt D- out D- D- DD3 3.3V D4 D- FULL SPEED CONNECTION Downstream port Host/Hub USB por transceivert USBDF01W5 Rt D+ in Ct Rd D+ out USBUF01W6 D2 Gnd D1 Upstream port D+ Peripheral transceiver D+ D+ CABLE D+ Ct Rt Ct Rt 3.3 V Rp Gnd Gnd Ct Rd D- in Rt D- out D- D- DD3 3.3V D4 D- LOW SPEED CONNECTION 3/9 Technical information USBUF01P6 2.1.1 EMI filtering Current FCC regulations requires that class B computing devices meet specified maximum levels for both radiated and conducted EMI. ● ● Radiated EMI covers the frequency range from 30 MHz to 1GHz. Conducted EMI covers the 450 kHz to 30 MHz range. For the types of devices utilizing the USB, the most difficult test to pass is usually the radiated EMI test. For this reason the USBUF01P6 device is aiming to minimize radiated EMI. The differential signal (D+ and D-) of the USB does not contribute significantly to radiated or conducted EMI because the magnetic field of both conductors cancels each other. The inside of the PC environment is very noisy and designers must minimize noise coupling from the different sources. D+ and D- must not be routed near high speed lines (clocks spikes). Induced common mode noise can be minimized by running pairs of USB signals parallel to each other and running grounded guard trace on each side of the signal pair from the USB controller to the USBUF device. If possible, locate the USBUF device physically near the USB connectors. Distance between the USB controller and the USB connector must be minimized. The 47 pF (Ct) capacitors are used to bypass high frequency energy to ground and for edge control, and are placed between the driver chip and the series termination resistors (Rt). Both Ct and Rt should be placed as close to the driver chip as is practicable. The USBUF01P6 ensures a filtering protection against electro-magnetic and radio frequency Interference thanks to its low-pass filter structure. This filter is characterized by the following parameters: ● ● ● cut-off frequency insertion loss high frequency rejection. USBUF01P6 typical attenuation curve. Figure 4. Measurement configuration. Figure 3. 0.00 dB -2.50 -5.00 -7.50 -10.00 -12.50 -15.00 -17.50 -20.00 -22.50 -25.00 1.0M 50Ω TEST BOARD UUx Vg 50Ω 3.0M 10.0M 30.0M f/Hz 100.0M 300.0M 1.0G 3.0G 4/9 USBUF01P6 Technical information 2.1.2 ESD protection In addition to the requirements of termination and EMC compatibility, computing devices are required to be tested for ESD susceptibility. This test is described in the IEC 61000-4-2 and is already in place in Europe. This test requires that a device tolerates ESD events and remains operational without user intervention. The USBUF01P6 is particularly optimized to perform ESD protection. ESD protection is based on the use of device which clamps at: V CL = V BR + R d ⋅ I PP This protection function is splitted in 2 stages. As shown in Figure 5. the ESD strikes are clamped by the first stage S1 and then its remaining overvoltage is applied to the second stage through the resistor Rt. Such a configuration makes the output voltage very low at the output. Figure 5. USBUF01P6 ESD clamping behavior. Rg S1 Rt S2 Rd VPP Vinput Voutput Rd Rload VBR VBR Device to be protected ESD Surge USBUF01P6 Figure 6. Measurement board. ESD SURGE 15kV Air Discharge TEST BOARD U Vin Vout To have a good approximation of the remaining voltages at both Vin and Vout stages, we give the typical dynamical resistance value Rd. By taking into account these following hypothesis : Rt>Rd, Rg>Rd and Rload>Rd, it gives these formulas: R g ⋅ V BR + R d ⋅ V g Vinput = ---------------------------------------------Rg R t ⋅ V BR + R d ⋅ Vinput Voutput = --------------------------------------------------------Rt The results of the calculation done for Vg = 8 kV, Rg = 330 Ω (IEC 61000-4-2 standard), VBR = 7 V (typ.) and Rd = 2 Ω (typ.) give: Vinput = 55.48 V Voutput = 10.36 V 5/9 Technical information USBUF01P6 This confirms the very low remaining voltage across the device to be protected. It is also important to note that in this approximation the parasitic inductance effect was not taken into account. This could be few tenths of volts during few ns at the Vinput side. This parasitic effect is not present at the Voutput side due the low current involved after the resistance Rt. The measurements done hereafter show very clearly (Figure 7.a) the high efficiency of the ESD protection: – – no influence of the parasitic inductances on Voutput stage Voutput clamping voltage very close to VBR (breakdown voltage) in the positive way and -VF (forward voltage) in the negative way Remaining voltage at both stages S1 (Vinput) and S2 (Voutput) during ESD surge. Figure 7. a: Positive surge b: Negative surge Please note that the USBUF01P6 is not only acting for positive ESD surges but also for negative ones. For these kinds of disturbances it clamps close to ground voltage as shown in Figure 7.b. 6/9 USBUF01P6 Package information 3 Package information Table 3. SOT-666 internal pad dimensions Dimensions b1 L1 L4 Ref. Millimeters Min. Typ. Max. Min. Inches Typ. Max. 0.024 0.007 0.013 A L3 b D E1 0.45 0.08 0.17 0.19 1.50 1.50 1.10 0.50 0.19 0.10 0.10 0.60 0.27 0.60 0.018 0.18 0.003 0.34 0.007 A3 b b1 D A L2 E A3 0.34 0.007 0.011 0.013 1.70 0.059 1.70 0.059 1.30 0.043 0.020 0.007 0.30 0.004 0.004 0.024 0.012 0.067 0.067 0.051 E E1 e L1 L2 e L3 L4 Figure 8. SOT-666 internal pad footprint (dimensions in mm) 0.30 0.50 0.99 0.21 0.62 1.40 2.60 0.20 7/9 Ordering information Table 4. Lead plating Lead plating thickness Lead material Lead coplanarity Body material Flammability USBUF01P6 Mechanical specifications Tin-lead 5 µm min 25 µm max Sn (100% Sn) 10 µm max Molded epoxy UL94V-0 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. 4 Ordering information Part Number USBUF01P6 Marking U Package SOT-666IP Weight 2.9 mg Base qty 3000 Delivery mode Tape and reel 5 Revision history Date September-2003 01-Jun-2004 08-Jun-2005 10-Mar-2006 16-Aug-2006 29-Aug-2006 Revision 1 2 3 4 5 6 First issue. SOT-666 Internal Pad version package change. Minor format changes; no content changed. Footprint and dimension graphic improved in packaging information. Ecopack statement added. Reformatted to current standard. Updated SOT-666IP package dimensions in Table 3. Typing error in table 2 on page 2: change W and kW unit to Ω and kΩ unit. Description of Changes 8/9 USBUF01P6 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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