UCC5617 18-Line SCSI Terminator (Reverse Disconnect) FEATURES DESCRIPTION • Complies with SCSI, SCSI-2, SCSI-3 and FAST-20 Standards • 2pF Channel Capacitance During Disconnect The UCC5617 provides 18 lines of active termination for a SCSI (Small Computers Systems Interface) parallel bus. The SCSI standard recommends and Fast-20 (Ultra) requires active termination at both ends of the cable. • 50µA Supply Current in Disconnect Mode • 110Ω Termination • SCSI Hot Plugging Compliant, 10nA Typical • +400mA Sinking Current for Active Negation • −650mA Sourcing Current for Termination • Trimmed Impedance to 5% Pin for pin compatible with the UC5609, the UCC5617 is ideal for high performance 5V SCSI systems, Termpwr 4.0V to 5.25V. During disconnect the supply current is only 50µA typical, which makes the IC attractive for lower powered systems. The UCC5617 is designed with a low channel capacitance of 2pF, which eliminates effects on signal integrity from disconnected terminators at interim points on the bus. The power amplifier output stage allows the UCC5617 to source full termination current and sink active negation current when all termination lines are actively negated. The UCC5617, as with all Unitrode terminators, is completely hot pluggable and appears as high impedance at the ter minating channels with TRMPWR=0V or open. Internal circuit trimming is utilized, first to trim the 110Ω impedance, and then most importantly, to trim the output current as close to the maximum SCSI-3 specification as possible, which maximizes noise margin in fast SCSI operation. Other features include thermal shutdown and current limit. This device is offered in low thermal resistance versions of the industry standard 28 pin wide body SOIC, TSSOP and PLCC. BLOCK DIAGRAM UDG-96073 Circuit Design Patented 4/97 Powered by ICminer.com Electronic-Library Service CopyRight 2003 UCC5617 ABSOLUTE MAXIMUM RATINGS Tempwr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+7V Signal Line Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0V to +7V Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1A Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .−65°C to +150°C Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .−55°C to +150°C Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300°C All currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. CONNECTION DIAGRAMS PLCC-28 (Top View) QP Package TSSOP-28 (Top View) PWP Package * DWP package pins 12 - 18 serve as both heatsink and signal ground. * PWP package pin 23 serves as signal ground; pins 7, 8, 9, 20, 21, and 22 serve as heatsink ground. DIL-24 (Top View) N Package SOIC-28 (Top View) DWP Package * N package for engineering samples only. Powered by ICminer.com Electronic-Library Service CopyRight 2003 * DWP package pin 28 serves as signal ground; pins 7, 8, 9, 20, 21, 22 serve as heatsink/ground. Note: Drawings are not to scale. 2 UCC5617 ELECTRICAL CHARACTERISTICS Unless otherwise stated these specifications apply for TA = 0°C to 70°C, TRMPWR = 4.75V, DISCNCT = 4.75V, TA = TJ. PARAMETER Supply Current Section Termpwr Supply Current TEST CONDITIONS Power Down Mode Output Section (Termination Lines) Termination Impedance Output High Voltage Maximum Output Current Output Leakage Output Capacitance Regulator Section Regulator Output Voltage Drop Out Voltage Short Circuit Current Sinking Current Capability Thermal Shutdown Thermal Shutdown Hysteresis Disconnect Section Disconnect Threshold Input Current MIN All termination lines = Open All termination lines = 0.2V DISCNCT = 0V (Note 3) 104.5 VTRMPWR = 4V (Note 1) 2.6 VLINE = 0.2V, TJ = 25°C −22.1 VLINE = 0.2V −20.7 VLINE = 0.2V, TRMPWR = 4V, TJ = 25°C (Note 1) –21 VLINE = 0.2V, TRMPWR = 4V (Note 1) –20 VLINE = 0.5V DISCNCT = 0V, TRMPWR = 0V to 5.25V, REG = 0.2V, VLINE = 5.25V DISCNCT = 2.4V (Note 2) 2.6 All Termination Lines = 0.2V VREG = 0V VREG = 3.5V –475 200 0.8 DISCNCT = 0V TYP MAX UNITS 1 420 50 2 450 100 mA mA µA 110 2.8 −23.3 −23.3 –23 –23 10 115.5 3 −24 −24 –24 –24 −22.4 400 Ω V mA mA mA mA mA nA 2 3.5 pF 2.8 0.4 −650 400 170 10 3 0.8 −850 800 V V mA mA °C °C 1.5 −10 2 −30 V µA Note 1: Measuring each termination line while other 17 are low (0.2V). Note 2: Guaranteed by design. Not 100% tested in production. Note 3: Tested by measuring IOUT with VOUT = 0.2V and VOUT with no load, then calculating: Z = VOUT N.L. – 0.2V . IOUT at 0.2V Procedure: 1) Measure VREG N.L. 2) Set VL = 0.2V; Measure IMAX at 0.2V 3) Impedance = VREG N.L. – 0.2V IMAX at 0.2V Figure 1.Termline Impedance Measurement Circuit Powered by ICminer.com Electronic-Library Service CopyRight 2003 3 UDG-97108 UCC5617 PIN DESCRIPTIONS DISCNCT: Taking this pin low causes the 18 channels to become high impedance and the chip to go into low-power mode; a high or open state allows the channels to provide normal termination. LINE 1-18: 110Ω termination channels. REG: Output of the internal 2.8V regulator. TRMPWR: Power for the IC. GND: Ground reference for the IC. APPLICATION INFORMATION UDG-96074 UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. 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