UC5608 18-Line Low Capacitance SCSI Active Terminator FEATURES DESCRIPTION • Complies with SCSI, SCSI-2 and SPI-2 Standards • 6pF Channel Capacitance during Disconnect The UC5608 provides 18 lines of active termination for a SCSI (Small Computer Systems Interface) parallel bus. The SCSI standard recommends active termination at both ends of the bus cable. • 100µA Supply Current in Disconnect Mode • Meets SCSI Hot Plugging Capability • −650mA Sourcing Current for Termination • +200mA Sinking Current for Active Negation • Provides Active Termination for 18 Lines • Logic Command Disconnects all Termination Lines • Trimmed Termination Current to 5% • Trimmed Impedance to 5% • Current Limit and Thermal Shutdown Protection The UC5608 is pin-for-pin compatible with its predecessors, the UC5601 and UC5602 - 18 Line Active Terminator. Parametrically the UC5608 has a 5% tolerance on impedance and current compared to a 3% tolerance on the UC5601 and the sink current is increased from 20 to 200mA. The low side clamps have been removed. Custom power packages are utilized to allow normal operation at full power conditions (2 Watts). When in disconnect mode the terminator will disconnect all terminating resistors and disable the regulator, greatly reducing standby power. The output channels remain high impedance even without Termpwr applied. Internal circuit trimming is utilized to trim the impedance to a 5% tolerance and, most importantly, to trim the output current to a 5% tolerance, as close to the max SCSI spec as possible, which maximizes noise margin in fast SCSI operation. Other features include 4.0 to 5.25V Termpwr, thermal shutdown and current limit. This device is offered in low thermal resistance versions of the industry standard 28 pin wide body SOIC, 28 pin wide body TSSOP, and 28 pin PLCC, as well as 24 pin DIP. BLOCK DIAGRAM UDG-94047 Circuit Design Patented 3/97 UC5608 ABSOLUTE MAXIMUM RATINGS Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V Regulator Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65°C to +150°C Operating Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −55°C to +150°C Lead Temperature (Soldering, 10 Sec.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C Unless otherwise specified all voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Unitrode Integrated Circuits databook for thermal limitations and considerations of packages. RECOMMENDED OPERATING CONDITIONS Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8V to 5.25V Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V Disconnect Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to Termpwr CONNECTION DIAGRAMS PLCC-28 (Top View) QP Package TSSOP-28 (Top View) PWP Package * PWP package pin 23 serves as signal ground; pins 7, 8, 9, 20, 21 and 22 serve as heatsink/ground. * QP package pins 12 - 18 serve as both heatsink and signal ground. DIL-24 (Top View) N or J Package SOIC-28 (Top View) DWP Package * 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 UC5608 ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 0°C to 70°C. TRMPWR = 4.75V, DISCNCT = Ground. TA = TJ. PARAMETER Supply Current Section Termpwr Supply Current TEST CONDITIONS MIN All termination lines = Open All termination lines = 0.5V DISCNCT = Open Power Down Mode Output Section (Terminator Lines) Terminator Impedance ∆ILINE = -5mA to -15mA Output High Voltage VTRMPWR = 4V (Note 1) Max Output Current VLINE = 0.5V Max Output Current Output Leakage Output Capacitance Regulator Section Regulator Output Voltage Regulator Output Voltage Line Regulation Drop Out Voltage Short Circuit Current Sinking Current Capability Thermal Shutdown Thermal Shutdown Hysteresis Disconnect Section Disconnect Threshold 104.5 2.65 TJ = 25°C -20.3 0°C < TJ < 70°C -19.8 TJ = 25°C -19.5 VLINE = 0.5V, TRMPWR = 4V (Note 1) 0°C < TJ < 70°C -19.0 0°C < TJ < 70°C -21.6 VLINE = 0.2V, TRMPWR = 4V to 5.25V TRMPWR = 0V to 5.25V V LINE = 0 to 4V DISCNCT = 4V REG = 0V VLINE = 5.25V TRMPWR = 0V to 5.25V, REG = Open VLINE = 0V to 5.25V DISCNCT = Open (Note 2) All Termination Lines = 4V TRMPWR = 4V to 6V All Termination Lines = 0.5V VREG = 0V VREG = 3.5V 2.8 2.8 -450 100 1.1 TYP MAX UNITS 17 400 100 25 430 150 mA mA µA 110 2.9 -21.5 -21.5 -21.5 -21.5 -24.0 10 10 115.5 3.0 -22.4 -22.4 -22.4 -22.4 -25.4 400 100 400 Ohms V mA mA mA mA mA nA µA nA 6 7 pF 2.9 2.9 10 1.0 -650 200 170 10 3 3 20 1.2 -950 500 V V mV V mA mA °C °C 1.4 1.7 V Note 1: Measuring each termination line while other 17 are low (0.5V). Note 2: Guaranteed by design. Not 100% tested in production. APPLICATION INFORMATION UDG-94048 Figure 1: Typical SCSI Bus Configuration UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. (603) 424-2410 • FAX (603) 424-3460 3 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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