UCC561 Low Voltage Differential SCSI (LVD) 27 Line Regulator Set FEATURES DESCRIPTION • SCSI SPI-2 LVD SCSI 27 Line Low Voltage Differential Regulator The UCC561 LVD Regulator set is designed to provide the correct references voltages and bias currents for LVD termination resistor networks (475 , 121 and 475 ). The device also provides a 1.3V output for Diff Sense signaling. With the proper resistor network, the UCC561 solution will meet the common mode bias impedance, differential bias, and termination impedance requirements of SPI-2 (Ultra2) and SPI-3 (Ultra3). • 2.7V to 5.25V Operation • Integrated Regulator Set for LVD SCSI • Differential Failsafe Bias This device incorporates into a single monolith, two sink/source reference voltage regulators, a 1.3V buffered output and protection features. The protection features include thermal shut down and active current limiting circuitry. The UCC561 is offered in 16-pin SOIC(DP) package. BLOCK DIAGRAM REF 1.3V TRMPWR 1.3V +/– 0.1V 7 DIFSENS 6 REG1 3 REG2 2 2.7V < 5.25V REF 1.75V 1.75V +/–50mV 200mA SOURCE/SINK SOURCE/SINK REGULATOR REF 0.75V 0.75V +/–50mV 200mA SOURCE/SINK 4 PGND UDG-98093 SLUS413 - MAY 1999 UCC561 CONNECTION DIAGRAMS ABSOLUTE MAXIMUM RATINGS TERMPWR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +6V Package Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2W Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C SOIC-16 (TOP VIEW) DP Packages Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. RECOMMENDED OPERATING CONDITIONS TERMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . 2.7V to 5.25V N/C 1 16 N/C TERMPWR 2 15 N/C REG2 3 14 N/C HSPGND 4 13 HSGND HSGND 5 12 HSGND REG1 6 11 N/C DIFSENS 7 10 N/C N/C 8 9 N/C ELECTRICAL CHARACTERISTICS: Unless otherwise specified these specifications apply for TA = 0°C to 70°C, TERMPWR = 3.3V. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS TERMPWR Supply Current Section TERMPWR Supply Current No Load TERMPWR Voltage 40.0 mA 5.25 V 1.75 1.8 V 2.7 Regulator Section 1.75 Volt Regulator REG1 (± 125mA) 1.7 1.3 Volt Regulator DIFSENS , No Load 1.2 1.3 1.4 V 0.75 Volt Regulator REG2 (± 125mA) 0.7 0.75 0.8 V –200 mA 1.75 Volt Regulator Source Current VO = 1.25 1.75 Volt Regulator Sink Current VO = 2.25 200 1.75 Volt Sink Current Limit mA 700 1.75 Volt Source Current Limit –700 mA mA 1.3 Volt Regulator Source Current DIFSENS, GND –5 –15 mA 1.3 Volt Regulator Sink Current DIFSENS, 2.4V 50 200 µA 0.75 Volt Regulator Source Current VO = 0.25 –200 mA 0.75 Volt Regulator Sink Current VO = 1.25 200 0.75 Source Current Limit mA 700 0.75 Sink Current Limit –700 Note 1: Guaranted by design. Not 100% tested in production. 2 mA mA UCC561 APPLICATION INFORMATION TERMPWR 2.7V TO 5.25V 2 4.7µF TERMPWR REF 1.3V DIFSENS: SOURCE ONLY FROM TERMPWR 7 DIFSENS DIFSENS 1.3V ± 0.1V SOURCE/SINK REGULATOR REF 1.75V 6 475 1% REG1 L1– 1.75V ± –50mV 200mA SOURCE/SINK 4.7µF 121 1% SOURCE/SINK REGULATOR REF 0.75V 4 PGND 0.75V ± –50mV 200mA SOURCE/SINK 3 475 1% REG2 L1+ 4.7µF 475 1% L27– 475 1% 121 1% L27+ UDG-98096 Figure 1. LVD SCSI discrete resistor stack. Table I. Resistor stack vs. standard. Outputs 107.3 Diff 112.9mV Diff Bias 237 Common Mode 1.25V Common Mode Specification 100 to 110 100mV to 125mV 100 to 300 1.2V to 1.30V Application Note: The resistor stack with the 1.75V and 0.75V reference will give the correct differential impedance, bias voltage, common mode differential impedance and common mode voltage as show in Table 1. UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. 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