UCC5610 18-Line 3-5 Volt Low Capacitance SCSI Active Terminator FEATURES DESCRIPTION • Complies with SCSI, SCSI-2, SCSI-3 and FAST-20 (Ultra) Standards • 2.75V to 7V Operation The UCC5610 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 cable. • 1.8pF Channel Capacitance during Disconnect • 0.5µA Supply Current in Disconnect Mode • 110 Ohm/2.5k Programmable Termination • Completely Meets SCSI Hot Plugging • -650mA Sourcing Current for Termination • +400mA Sinking Current for Active Negation Drivers • Trimmed Termination Current to 4% • Trimmed Impedance to 7% • Current Limit and Thermal Shutdown Protection The UCC5610 is ideal for high performance 3.3V SCSI systems. The key features contributing to such low operating voltage are the 0.1V drop out regulator and the 2.75V reference. The reduced reference voltage was necessary to accommodate the lower termination current dictated in the SCSI-3 specification. During disconnect the supply current is typically only 0.5µA, which makes the IC attractive for battery powered systems. The UCC5610 is designed with an ultra low channel capacitance of 1.8pF, which eliminates effects on signal integrity from disconnected terminators at interim points on the bus. The UCC5610 can be programmed for either a 110 ohm or 2.5k ohm termination. The 110 ohm termination is used for standard SCSI bus lengths and the 2.5k ohm termination is typically used in short bus applications. When driving the TTL compatible DISCNCT pin directly, the 110 ohm termination is connected when the DISCNCT pin is driven low, and disconnected when driven high. When the DISCNCT pin is driven through an impedance between 80k and 150k, the 2.5k ohm termination is connected when the DISCNCT pin is driven low, and disconnected when driven high. continued BLOCK DIAGRAM UDG-94128-1 Circuit Design Patented 2/97 Powered by ICminer.com Electronic-Library Service CopyRight 2003 UCC5610 Description Continued ohm termination impedance to a 7% tolerance, and then most importantly, to trim the output current to a 4% tolerance, as close to the max SCSI-3 spec as possible, which maximizes noise margin in FAST-20 SCSI operation. The power amplifier output stage allows the UCC5610 to source full termination current and sink active negation current when all termination lines are actively negated. The UCC5610 is pin for pin compatible with Unitrode’s other 18 line SCSI terminators, allowing lower capacitance and lower voltage upgrades to existing systems. The UCC5610, as with all Unitrode terminators, is completely hot pluggable and appears as high impedance at the terminating channels with VTRMPWR = 0V or open. Other features include thermal shutdown and current limit. Internal circuit trimming is utilized, first to trim the 110 This device is offered in low thermal resistance versions of the industry standard 28 pin wide body SOIC, 24 pin wide body DIP and 28 pin PLCC. ABSOLUTE MAXIMUM RATINGS CONNECTION DIAGRAMS Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +7V Regulator Output Current . . . . . . . . . . . . . . . . . . Self-regulating 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. PLCC-28 (Top View) QP Package RECOMMENDED OPERATING CONDITIONS Termpwr Voltage . . . . . . . . . . . . . . . . . . . . . . . . 2.75V to 5.25V Signal Line Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . 0V to +5V Disconnect Input Voltage . . . . . . . . . . . . . . . . . . 0V to Termpwr * 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. Powered by ICminer.com Electronic-Library Service CopyRight 2003 Note: Drawings are not to scale. 2 UCC5610 ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = 0°C to 70°C. TRMPWR = 3.3V, DISCNCT = 0V, RDISCNCT= 0 ohms. TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Supply Current Section Termpwr Supply Current Power Down Mode All termination lines = Open 1 2 mA All termination lines = 0.2V 415 455 mA DISCNCT = Termpwr 0.5 5 µA Output Section (110 ohms - Terminator Lines) Terminator Impedance (Note 4) 102.3 110 117.7 Ohms Output High Voltage (Note 1) 2.5 2.7 3.0 V Max Output Current VLINE = 0.2V, TJ = 25°C VLINE = 0.2V VLINE = 0.2V, TRMPWR = 3V, TJ = 25°C (Note 1) VLINE = 0.2V, TRMPWR = 3V (Note 1) −22.1 −23 −24 mA −21 −23 −24 mA −20.2 −23 −24 mA −19 −23 −24 mA −22.4 mA Output Leakage DISCNCT = 2.4V, TRMPWR = 0V to 5.25V 10 400 nA Output Capacitance DISCNCT = 2.4V (Note 2, 3) (DWP Package) 1.8 2.5 pF kΩ VLINE = 0.5V Output Section (2.5k ohms - Terminator Lines) (RDISCNCT = 80k ohms) Terminator Impedance 2 2.5 3 Output High Voltage TRMPWR = 3V (Note 1) 2.5 2.7 3.0 V Max Output Current VLINE = 0.2V −0.7 −1 −1.4 mA VLINE = 0.2V, TRMPWR = 3V (Note 1) −0.6 −1 −1.5 mA Output Leakage DISCNCT = 2.4V, TRMPWR = 0 to 5.25V 10 400 nA Output Capacitance DISCNCT = 2.4V (Note 2, 3) (DWP Package) 1.8 2.5 pF Regulator Section Regulator Output Voltage 5.25V > TRMPWR > 3V Drop Out Voltage All Termination Lines = 0.2V 2.5 2.7 3.0 V 0.1 0.2 V Short Circuit Current VREG = 0V −450 −650 −800 mA Sinking Current Capability VREG = 3V 200 400 800 mA Thermal Shutdown (Note 2) 170 °C Thermal Shutdown Hysteresis (Note 2) 10 °C Disconnect Section Disconnect Threshold RDISCNCT = 0 & 80k Input Current DISCNCT = 0V Note 1: Note 2: Note 3: Note 4: 0.8 Measuring each termination line while other 17 are low (0.2V). Guaranteed by design. Not 100% tested in production. Output capacitance is measured at 0.5V. Tested by measuring IOUT with VOUT = 0.2V and VOUT = VREG - 0.1V then calculating the impedance. Powered by ICminer.com Electronic-Library Service CopyRight 2003 3 1.5 2.0 V 30 50 µA UCC5610 APPLICATION INFORMATION UDG-94130 Figure 1: Typical SCSI Bus Configurations Utilizing A UCC5610 Device UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. (603) 424-2410 • FAX (603) 424-3460 Powered by ICminer.com Electronic-Library Service CopyRight 2003 4 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. 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INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER’S RISK. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof. Copyright 1999, Texas Instruments Incorporated Powered by ICminer.com Electronic-Library Service CopyRight 2003