UC560 27-Line SCSI Source/Sink Regulator FEATURES DESCRIPTION • Complies with SCSI, SCSI-2, SCSI-3 SPI and Ultra SCSI (Fast-20) The UC560 provides current for up to 27 lines of active termination for a SCSI (Small Computers Systems Interface) parallel bus. The SCSI standard requires active termination at both ends of the cable. The UC560 is based on the UC5603 and UC5613 SCSI Active Terminators. It uses the voltage regulator and internal logic circuits of those parts, but has no termination circuits. The UC560 provides greater source current drive capability compared to the UC5603 and UC5613. • 2.85V Regulated Output Voltage With 1.4% Tolerance • Provides Current for up to 27 Lines of Active Termination for SCSI Buses • −750mA Sourcing Current for Termination • +300mA Sinking Current for Active Negation Drivers • 0.9V Dropout Voltage Regulator at 750mA and 2.75V Output • 100µA Supply Current in Disconnect Mode The UC560 sink current maintains regulation with all active-negation drivers negated. It provides a disconnect feature which disables the regulator to greatly reduce standby power. Internal circuit trimming is utilized for a 1.4% tolerance output voltage. Other features include thermal shutdown and current limit for short circuit conditions. The UC560 is available in low thermal resistance versions of the industry standard 8-pin power SOIC, 5-pin TO-220 and 5-pin TO-263. • Current Limit and Thermal Shutdown Protection • Low Thermal Resistance Surface Mount Packages BLOCK DIAGRAM Pin Numbers refer to 8-pin DP package. UDG-95136-1 SLUS213 - APRIL 1998 UC560 CONNECTION DIAGRAMS ABSOLUTE MAXIMUM RATINGS TERMPWR Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V ENBL Voltage . . . . . . . . . . . . . . . . –0.3V to TERMPWR + 0.3V Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4A Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5W Storage Temperature . . . . . . . . . . . . . . . . . . . −65°C to +150°C Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C SOIC-8 (Top View) DP Package 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 Note: Pins 2,3,6, and 7 are heat sinking pins. Pin 2 is the connect point for electrical ground. TERMPWR Voltage . . . . . . . . . . . . . . . . . . . . . . . . 4.0V to 6.0V ENBL Voltage . . . . . . . . . . . . . . . . . . . . . . . . 0V to TERMPWR 5-Pin TO-220 (Top View) T Package 5-Pin TO-263 (Top View) TD Package Note: TAB is ground. Note: TAB is ground. ELECTRICAL CHARACTERISTICS Unless otherwise specified, TA = 0°C to 70°C, TERMPWR = 4.75V, ENBL = 0V, COUT = 4.7µF, CTERMPWR = 4.7µF, TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Supply Current Section TERMPWR Supply Current No Load 16 22 mA IOUT = –700mA Power Down Mode ENBL = 2.0V 710 750 mA 100 140 µA 2.85 2.89 V Regulator Section Regulator Output Voltage 25°C, No Load 2.81 Load Regulation IOUT = 300mA to –750mA (Note 2) 25 30 mV Line Regulation TERMPWR = 4.0V to 6.0V, No Load (Note 2) 10 20 mV 0.9 1.2 V 500 600 mA 1 2 mA Dropout Voltage IOUT = –750mA, VOUT = 2.75V Short Circuit Current VOUT = 0.0V Sinking Current VOUT = 3.5V Thermal Shutdown (Note 1) 170 °C Thermal Shutdown Hysteresis (Note 1) 10 °C –0.85 ENBL = 2.0V, VOUT = 3.0V –1.3 A Shutdown Section ENBL Threshold 1.1 1.4 Threshold Hysteresis 100 ENBL Output Current –10 Note 1: Guaranteed by design. Not 100% tested in production. Note 2: Tested at a constant junction temperature by low duty cycle pulse testing. 2 1.7 V mV –15 µA UC560 PIN DESCRIPTIONS rent to prevent damage. When the part is in disabled mode (ENBL ≥ 1.4V typical), the output goes to 0V with no external supply source on OUT. The part will sink current, though, if there is an external supply voltage applied to OUT when in disabled mode. For best perfomance, a 4.7µF low ESR capacitor is recommended. ENBL: Enable Bar pin. The ENBL function is active low, and the pin will source 10µA typically when at ground and TERMPWR is between 4V and 6V. The part will go into disable mode if ENBL is above 1.4V typical, and will turn back on when ENBL drops below 1.3V typical. The part also greatly reduces TERMPWR current when disabled (100µA typical). TERMPWR: Supply voltage pin. The pin should be decoupled with at least a 2.2µF low ESR output capacitor. For best perfomance, a 4.7µF low ESR capacitor is recommended. Lead lengths should be kept at a minimum. GND: Ground pin. OUT: 2.85V regulated output voltage pin. The part is internally current limited for both sinking and sourcing cur- APPLICATIONS INFORMATION UDG-96034 UDG-96033 Figure 1. Typical SCSI Bus Configuration Utilizing UC560 Device Figure 2. Typical Wide SCSI Bus Configuration Utilizing UC560 Device 3 UC560 TYPICAL CHARACTERISTICS IOUT = -750mA NO LOAD IOUT = 300mA LOAD REG (mV) 2.9 2.89 VOUT (V) 2.88 2.87 2.86 2.85 2.84 2.83 2.82 2.81 2.8 0 20 40 60 30 29 28 27 26 25 24 23 22 21 20 0 80 Figure 3. VOUT vs Temperature 40 60 80 Figure 5. Load Regulation vs. Temperature (IOUT = 300mA to –750mA) 1.3 4 1.2 2 LINE REG (mV) VIN - VOUT (V) 20 TEMPERATURE (°C) TEMPERATURE (°C) 1.1 1 0.9 0.8 0 -2 -4 -6 -8 0.7 -10 -12 0.6 0 20 40 60 0 80 20 40 60 TEMPERATURE (°C) TEMPERATURE (°C) Figure 4. Dropout Voltage vs. Temperature (IOUT = –750mA, VOUT = 2.75V) Figure 6. Line Regulation vs Temperature (TERMPWR = 4.0V to 6.0V) UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. 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