UCC5641 Low Voltage Differential (LVD) SCSI 9 Line Terminator FEATURES DESCRIPTION • First LVD only Active Terminator The UCC5641 is an active terminator for Low Voltage Differential (LVD) SCSI networks. This LVD only design allows the user to reach peak bus performance while reducing system cost. The device is designed as an active Y-terminator to improve the frequency response of the LVD Bus. Designed with a 1.5pF channel capacitance, the UCC5641 allows for minimal bus loading for a maximum number of peripherals. With the UCC5641, the designer will be able to comply with the Fast-40 SPI-2 and Fast-80 SPI-3 specifications. The UCC5641 also provides a much-needed system migration path for ever improving SCSI system standards. This device is available in the 24 pin TSSOP and 28 pin TSSOP for ease of layout use. • Meets SCSI SPI-2 Ultra2 (Fast-40) and Ultra3 / Ultra160 (Fast-80) Standards • 2.7V to 5.25V Operation • Differential Failsafe Bias • Reversed Disconnect Polarity The UCC5641 is not designed for use in single ended or high voltage differential systems. BLOCK DIAGRAM SOURCE ONLY FROM TRMPWR AND THE ENABLED TERMINATIONS TRMPWR 28 SOURCE 5–15mA SINK 200µA MAXIMUM (NOISE LOAD) 2.7V to 5.25V REF 1.3V OPEN CIRCUIT ON POWER OFF OR OPEN CIRCUIT IN A DISABLED TERMINATOR MODE 12 DIFSENS 1.3V ± 0.1V HIGH POWER DIFFERENTIAL 2.4V > 1.9V DIFFB 20k 11 0.1µF 0.7V > 0.5V SOURCE/SINK REGULATOR LOW FREQUENCY FILTER 50Hz – 60Hz 27 LVD* 4 L1– 3 L1+ 26 L9– 25 L9+ HIGH IMPEDANCE RECEIVER EVEN WITH POWER OFF SINGLE ENDED 124 REF 1.25V 10µA 124 DISCNCT 15 14 GND 1 56mV – + 52 56mV + – 52 56mV – + 52 56mV + – 52 REG 4.7µF * 28 pin package only SLUS397 - JANUARY 2000 UDG-99160 UCC5641 CONNECTION DIAGRAMS TSSOP-28 (Top View) PW28 Package TSSOP-24 (Top View) PW24 Package REG 1 24 TRMPWR L1+ 2 23 L9– L1– 3 22 L9+ L2+ 4 21 L8– L2– 5 20 L8+ L3+ 6 19 L3– 7 L4+ REG 1 28 TRMPWR N/C 2 27 LVD L1+ 3 26 L9– L1– 4 25 L9+ L2+ 5 24 L8– L7– L2– 6 23 L8+ 18 L7+ L3+ 7 22 L7– 8 17 L6– L3– 8 21 L7+ L4– 9 16 L6+ L4+ 9 20 L6– DIFFB 10 15 L5– L4– 10 19 L6+ DIFSENS 11 14 L5+ DIFFB 11 18 L5– GND 12 13 DISCNCT DIFSENS 12 17 L5+ N/C 13 16 N/C GND 14 15 DISCNCT ABSOLUTE MAXIMUM RATINGS TERMPWR Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6V Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to 3.6V Package Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1W Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C Currents are positive into negative out of the specified terminal. consult Packaging Section of Databook for thermal limitations and considerations of package. RECOMMENDED OPERATING CONDITIONS TERMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.25V ELECTRICAL CHARACTERISTICS: Unless otherwise stated, specifications apply for TA = 0°C to 70°C, TRMPWR = 3.3V. TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS TRMPWR Supply Current Section TRMPWR Supply Current No Load 25 mA Disabled Terminator 400 µA 5.25 V TRMPWR Voltage 2.7 2 UCC5641 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, specifications apply for TA = 0°C to 70°C, TRMPWR = 3.3V. TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS 1.15 1.25 1.35 –100 –80 Regulator Section 1.25V Regulator DIFSENS connected to DIFFB 1.25V Regulator Source Current DIFSENS connected to DIFFB 1.25V Regulator Sink Current DIFSENS connected to DIFFB 1.3V Regulator 1.3V Regulator Source Current 1.3V Sink Current V mA 80 100 mA DIFFB connected to GND 1.2 1.3 1.4 V DIFSENS to GND –15 –5 mA DIFSENS to 3.3V 50 200 µA Differential Impedance –2.5mA to 4.5mA 100 105 110 Ω Common Mode Impedance L+ connected to L– 110 150 165 Ω Differential Bias Voltage No load, L+ or L– 125 mV 1.25 1.35 V 10 400 nA 3 pF Differential Termination Section 100 Common Mode Bias 1.15 Output Leakage, Disconnect DISCNCT, TRMPWR = 0 to 5.25V, VLINE = 0.2 to 5.25V Output Capacitance Single ended measurement to ground (Note 1) Low Voltage Differential (LVD) Status Bit Section ISOURCE VLOAD = 2.4V ISINK VLOAD = 0.4V –6 2 –4 5 mA mA Disconnect & Differential Sense Input Section DISCNCT Threshold Input Current 0.8 At 0V and 3.3V –30 2 V µA –10 Differential Sense SE to LVD Threshold 0.5 0.7 V Differential Sense LVD to HPD Threshold 1.9 2.4 V Note 1: Guaranteed by design. Not 100% tested in production. PIN DESCRIPTION DIFFB: Differential sense filter pin should be connected to a 0.1µF capacitor and 20k resistor to Diff Sense. Ln +: Positive line for differential applications for the SCSI Bus. DIFSENS: The SCSI bus differential sense line to detect what type of devices are connected to the SCSI Bus. LVD: (28 pin package only) Indicates that the bus is in LVD mode. DISCNCT: Disconnect pin shuts down the terminator when it is not at the end of the bus. REG: Regulator bypass; must be connected to a 4.7 F capacitor to ground. GND: Ground. TRMPWR: VIN 2.7V to 5.25V supply. Ln –: Negative line in differential applications for the SCSI Bus. 3 UCC5641 APPLICATION INFORMATION UCC5641PW28 Termpower 28 TRMPWR 27 LVD 15 UCC5641PW24 L1+ 3 2 L1+ L1– 4 3 L1– L9+ 25 22 L9+ L9– 26 23 L9– Termpower CONTROL LINES (9) DISCNCT REG DIFFB 1 11 4.7µF DIFF SENSE 12 20k 11 20k DISCNCT 13 DIFFB REG 10 1 0.1µF TRMPWR 4.7µF 0.1µF UCC5641PW28 28 TRMPWR 24 UCC5641PW24 L1+ 3 2 L1+ L1– 4 3 L1– TRMPWR 24 DATA LINES (9) 4.7µF 15 DISCNCT L9+ 25 22 L9+ L9– 26 23 L9– REG DIFFB DIFFB REG 1 11 10 1 4.7µF 4.7µF UCC5641PW28 28 4.7µF DISCNCT 13 TRMPWR UCC5641PW24 L1+ 3 2 L1+ L1– 4 3 L1– L9+ 25 22 L9+ L9– 26 23 L9– TRMPWR 24 DATA LINES (9) 15 S1* DISCNCT DISCNCT 13 REG DIFFB DIFFB REG 1 11 10 1 S2* 4.7µF 4.7µF UDG-99159 * CLOSE S1 AND S2 TO DISABLE TERMINATORS Figure 1. Application diagram. UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. 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