® REG5608 RE G5 60 8 RE G5 60 8 LOW CAPACITANCE 18-Line SCSI ACTIVE TERMINATOR FEATURES DESCRIPTION ● ACTIVE 18-Line TERMINATOR ● 2pF CAPACITANCE PER LINE IMPORTANT FOR SCSI FAST-20 ● ON-CHIP TERMINATION RESISTORS ● ALL TERMINATIONS DISCONNECT WITH SINGLE LOGIC SIGNAL ● 325mA CURRENT SINKING FOR ACTIVE NEGATION ● 22.4mA PER LINE DURING ASSERTION The REG5608 is a low capacitance 18-line active terminator for SCSI (Small Computer Systems Interface) parallel bus systems. On-chip resistors and voltage regulator provide the prescribed SCSI bus termination. Low line capacitance (2pF) meets requirements for high data rate systems. All terminations can be disconnected from the bus with a single logic control line. In the disconnect mode, output lines remain high impedance with or without power applied. This allows “hot socket” equipment plugging as required for “plug and play” applications. ● CURRENT LIMIT AND THERMAL LIMIT ● HOT-SOCKET CAPABLE ● 28-Lead SOIC and SSOP PACKAGES The internal voltage regulator is temperature-compensated to assure proper termination characteristics over a wide operating range. Output current and thermal limit circuitry protect against damage. The REG5608 is available in 28-lead SOIC and fine-pitch SSOP packages and is specified for 0°C to 70°C operation. 2.9V Regulator TERMPWR Reg Out 110Ω 110Ω Thermal Limit Current Limit Disconnect SCSI Termination Lines 110Ω Switch Drive (18 lines) International Airport Industrial Park • Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706 Tel: (520) 746-1111 • Twx: 910-952-1111 • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 © 1995 Burr-Brown Corporation PDS-1305 Printed in U.S.A. November, 1995 SPECIFICATIONS At TA = 0°C to +70°C, TERMPWR = 4.75V, and Disconnect = Low and IREG OUT = 0, unless otherwise specified. REG5608U REG5608E PARAMETERS CONDITIONS POWER SUPPLY TERMPWR Supply Voltage TERMPWR Supply Current TERMINATION LINES Termination Impedance Output Termination High Voltage(1) Maximum Line Current Line Leakage Current Line Capacitance REG5608U SO-28 Package REG5608E SSOP-28 REGULATOR Output Voltage Line Regulation Drop-Out Voltage Source Current Limit Sink Current Limit Thermal Shutdown, TJ DISCONNECT LOGIC INPUT Input High Voltage Input Low Voltage Input Low Current Threshold Hysteresis MIN TYP 4 All Termination Lines Open Circuit All VLINE = 0.5V Disconnect = High ∆ILINE = 5 to 15mA TERMPWR = 4.0V VLINE = 0.5V TA = 0°C to 70°C TA = 25°C TERMPWR = 4.0V, TA=0°C to 70°C(1) TERMPWR = 4.0V, TA = 25°C(1) Disconnect = High TERMPWR = 5.25V, VLINE = 0V TERMPWR = 5.25V, VLINE = 5.25V TERMPWR = 0V, VLINE = 5.25V Disconnect = High 18 390 5 MAX UNITS 5.25 25 430 V mA mA mA 104.5 2.65 110 2.9 115.5 3.0 Ω V 19.8 20.3 19.0 19.5 21.5 21.5 21.5 21.5 22.4 22.4 22.4 22.4 mA mA mA mA 10 10 10 400 400 400 nA nA nA 2.5 1.8 2.8 TERMPWR = 4.0 to 6.0V All VLINE = 0.5V, ∆Reg Out = 100mV Reg Out = 0V Reg Out = 3.5V 400 100 (Logic High = Switches Open) (Logic Low = Switches Closed) 2 0 2.9 2 0.9 550 325 145 10 50 TEMPERATURE RANGE Specification Storage θJL (Junction to Lead) 0 -40 25 20 pF pF 3.0 20 1.2 950 500 V mV V mA mA °C TERMPWR 0.8 20 V V µA mV 70 150 °C °C °C/W NOTE: (1) Measurement of each termination line while the other 17 lines are held low (VLINE = 0.5V). The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems. ® REG5608 2 CONNECTION DIAGRAM Top View SOIC SSOP Disconnect 1 28 GND Termination Line 1 2 27 Termination Line 18 Termination Line 2 3 26 Termination Line 17 Termination Line 3 4 25 Termination Line 16 Termination Line 4 5 24 Termination Line 15 Termination Line 5 6 23 Termination Line 14 (Thermal) GND 7 22 GND (Thermal) 8 21 GND (Thermal) REG5608 (Thermal) GND (Thermal) GND 9 20 GND (Thermal) Termination Line 6 10 19 Termination Line 13 Termination Line 7 11 18 Termination Line 12 Termination Line 8 12 17 Termination Line 11 Termination Line 9 13 16 Termination Line 10 TERMPWR 14 15 Reg Out NOTE: Pin 28 is electrical ground. Connect pins 7, 8, 9, 20, 21, 22 to large circuit trace for proper heat sinking. Connect to ground or leave open-circuit. ABSOLUTE MAXIMUM RATINGS ELECTROSTATIC DISCHARGE SENSITIVITY TERMPWR Voltage ............................................................................. +7V Signal Line Voltage ................................................................... 0V to +7V Junction Temperature .................................................................... +150°C Storage Temperature ..................................................... –40°C to +150°C This integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. PACKAGE/ORDERING INFORMATION MODEL REG5608U REG5608E PACKAGE PACKAGE DRAWING NUMBER(1) Plastic 28-Lead SOIC Plastic 28-Lead SSOP 217 324 NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix D of Burr-Brown IC Data Book. ® 3 REG5608 TYPICAL PERFORMANCE CURVES TA = 25°C, TERMPWR = 4.75V unless otherwise noted. TERMINATION CURRENT vs TEMPERATURE LINE CAPACITANCE vs PIN NUMBER 10 Line Capacitance (pF) Termination Current (mA) 23 22 VLINE = 0.5V 21 20 8 First-Generation Terminator 6 4 REG5608U SOIC Package 2 19 –25 REG5608E SSOP Package 0 0 25 50 75 100 125 2 27 Temperature (°C) 3 26 4 25 5 24 6 23 10 19 11 18 12 17 13 16 Pin Number shutdown during normal operation is an indication of inadequate heat sinking and/or excessive power dissipation. APPLICATION INFORMATION Figure 1 shows a typical SCSI parallel bus termination circuit. Bypass capacitors should be connected to TERMPWR and Reg Out pins as shown. The terminator's internal power is dissipated primarily by conduction through the package leads to circuit board traces. It is important to connect the six thermal ground leads (7, 8, 9, 20, 21, 22) to a large circuit trace—see Figure 2. Typical measured values of thermal resistance for various circuit board materials are shown. These are approximate values. Variations in circuit board pattern, mounting techniques, air flow, proximity to other circuit boards and heat sources will affect thermal performance. Line capacitance of the REG5608 has been reduced to less than one-fourth that of the first-generation integrated terminator ICs. Capacitance difference between package types and variation by pin number is shown in the typical performance curve, “Line Capacitance vs Pin Number.” It shows that the SSOP package provides the lowest capacitance with typical values under 2pF. This variation is produced primarily by the differences in the interconnection length to the IC. Of course, actual line capacitance on a circuit board is generally determined by circuit board layout. To achieve lowest line capacitance, minimize the total circuit board interconnection length from the interface cable to the SCSI transceiver IC and to the REG5608 terminator. A simple experiment will determine whether the actual circuit board layout is adequate (i.e., θBA is low enough) so that the maximum recommended junction temperature of the REG5608 will not be exceeded. The procedure uses the internal thermal shutdown feature of the REG5608 (at TJ ≈ 145°C) to determine when the junction is approximately 20°C above the maximum recommended junction temperature (TJ = 125°C). Operate the circuit with normal or other desired test electrical conditions. Increase the ambient temperature and determine the value at which thermal limit occurs (by sensing a sudden drop in VREG output). At this point TJ is approximately 145°C. If this occurs at an ambient temperature of more than 20°C above the system ambient temperature design goal, the TJ will not exceed 125°C under the same electrical conditions when the ambient temperature is at the system design goal value. THERMAL CONSIDERATIONS The REG5608 has internal current limit and thermal shutdown that protect it from damage in case of output short-circuit or overload. The current limit is approximately 550mA and thermal shutdown activates at a junction temperature of approximately 145°C. For good long-term reliability, the junction temperature should not exceed 125°C. Any tendency to activate the thermal ® REG5608 4 4V to 5.25V 4.7µF Tantalum + 14 TERMPWR Low = Termination On High = Disconnect 1 28 Disconnect REG5608 Reg Out 15 T18 To Controller Tranceivers + 4.7µF Tantalum Gnd T1 27 2 (18 Lines) To other SCSI Devices and opposite-end termination SCSI Parallel Bus FIGURE 1. SCSI Parallel Bus Termination. Thermal ground (leads 7, 8, 9, 20, 21, 22). Connect to circuit ground or leave open-circuit. TJ = TA + PD θJA PACKAGE CIRCUIT BOARD MATERIAL θJL θBA θJA JUNCTION TO LEAD + BOARD TO AMBIENT = JUNCTION TO AMBIENT (°C/W) (°C/W) (°C/W) SO-28 1-Layer(1) 3-Layer(2) Aluminum(3) 20 20 20 + + + 30 21 12 = = = 50 41 32 SSOP-28 1-Layer(1) 3-Layer(2) Aluminum(3) 20 20 20 + + + 36 23 13 = = = 56 43 33 NOTES: (1) Single-side layout on 0.062 inch FR4, 1 oz copper. (2) Three-layer layout on 0.062 inch FR4, 1 oz copper. (3) Aluminum 0.062 inch substrate, 0.003 insulation, one layer, 1 oz copper (Thermal Clad, Bergqueist Co.) FIGURE 2. Circuit Board Layout. ® 5 REG5608