MC34268 800 mA, 2.85 V, SCSI-2 Active Terminator, Low Dropout Voltage Regulator The MC34268 is a medium current, low dropout positive voltage regulator specifically designed for use in SCSI-2 active termination circuits. This device offers the circuit designer an economical solution for precision voltage regulation, while keeping power losses to a minimum. The regulator consists of a 1.0 V dropout composite PNP/NPN pass transistor, current limiting, and thermal limiting. These devices are packaged in the SOIC-8 and DPAK-3 and SOT-223 surface mount power packages. Applications include active SCSI-2 terminators and post regulation of switching power supplies. http://onsemi.com MARKING DIAGRAMS 8 8 1 * 2.85 V Output Voltage for SCSI-2 Active Termination 1.0 V Dropout Output Current in Excess of 800 mA Thermal Protection Short Circuit Protection Output Trimmed to 1.4% Tolerance No Minimum Load Required Space Saving DPAK-3, SOT-223 and SOIC-8 Surface Mount Power Packages Pb-Free Packages are Available 34268 ALYW 1 A L Y W Features * * * * * * * * SOIC-8 D SUFFIX CASE 751 = Assembly Location = Wafer Lot = Year = Work Week GND 1 8 2 7 3 6 4 5 Output Input NC Output NC (Top View) DPAK-3 DT SUFFIX CASE 369A 34268 ALYWW SOT-223 ST SUFFIX CASE 318E AYW 268ST 1 3 Simplified Block Diagram 1 3 Input 4 Thermal Limiting Control Circuit 1 2 3 Pin 1. Ground 2. Output 3. Input 4. Output (Top View) Current Limit Output Heatsink surface (shown as terminal 4 in case outline drawing) is connected to Pin 2. ORDERING INFORMATION See detailed ordering and shipping information in the package dimensions section on page 3 of this data sheet. Ground Semiconductor Components Industries, LLC, 2005 April, 2005 - Rev. 6 1 Publication Order Number: MC34268/D MC34268 MAXIMUM RATINGS Rating Power Supply Input Voltage Power Dissipation and Thermal Characteristics DT Suffix, Plastic Package, Case 369A TA = 25C, Derate Above TA = 25C Thermal Resistance, Junction-to-Case Thermal Resistance, Junction-to-Air D Suffix, Plastic Package, Case 751 TA = 25C, Derate Above TA = 25C Thermal Resistance, Junction-to-Case Thermal Resistance, Junction-to-Air ST Suffix, Plastic Package, Case 318E TA = 25C, Derate Above TA = 25C Thermal Resistance, Junction-to-Case Thermal Resistance, Junction-to-Air Operating Ambient Temperature Range Maximum Die Junction Temperature Storage Temperature Symbol Value Unit Vin 15 V PD RqJC RqJA Internally Limited 5.0 87 W C/W C/W PD RqJC RqJA Internally Limited 22 140 W C/W C/W PD RqJC RqJA Internally Limited 15 245 W C/W C/W TA 0 to +125 C TJ +150 C Tstg - 55 to +150 C Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. ELECTRICAL CHARACTERISTICS (Vin = 4.25 V, CO = 10 mF, for typical values TA = 25C, for min/max values TA = 0C to +125C, unless otherwise noted.) Symbol Min Typ Max Unit VO 2.81 2.76 2.85 2.85 2.89 2.93 V Line Regulation (Vin = 4.25 V to 15 V, IO = 0 mA, TA = 25C) Regline - - 0.3 % Load Regulation (IO = 0 mA to 800 mA, TA = 25C) Regload - - 0.5 % Dropout Voltage (IO = 490 mA) Vin - VO - 0.95 1.1 V RR 55 - - dB I(max) 800 - - mA IB - 5.0 to 3.0 8.0 mA IL(min) - - 0 mA Characteristic Output Voltage (TA = 25C, IO = 0 mA) Output Voltage, over Line, Load, and Temperature (Vin = 3.9 V to 15 V, IO = 0 mA to 490 mA) Ripple Rejection (f = 120 Hz) Maximum Output Current (Vin = 5.0 V) Bias Current (Vin = 4.25 V, IO = 0 mA) I O, OUTPUT CURRENT VO , OUTPUT VOLTAGE DEVIATION Minimum Load Current to maintain Regulation (Vin = 15 V) V in -VO , DROPOUT VOLTAGE (V) 1.5 TJ = 25C 1.3 1.1 0.9 0.7 0.5 0 200 400 600 800 1000 IO, OUTPUT LOAD CURRENT (mA) Figure 1. Dropout Voltage versus Output Load Current Vin = 5.0 V CO = 10 mF TA = 25C 20 ms/DIV Figure 2. Transient Load Regulation http://onsemi.com 2 MC34268 Vin 5.0V 1N5819 MC34268 SCSI Regulator 10 110W VO CO GN D 10 To SCSI Bus Figure 3. Typical SCSI Application The MC34268 requires an external 10 mF capacitor with an ESR of less than 10 W for stability over temperature. With economical electrolytic capacitors, cold temperature operation can pose a stability problem. As temperature decreases, the capacitance also decreases and the ESR increases, which could cause the circuit to oscillate. Tantalum capacitors may be a better choice if small size is a requirement. Also, the capacitance and ESR of a tantalum capacitor is more stable over temperature. 180 JA , THERMAL RESISTANCE JUNCTION-TO-AIR ( C/W) JA , THERMAL RESISTANCE JUNCTION-TO-AIR ( C/W) Figure 3 is a circuit of a typical SCSI terminator application. The MC34268 is designed specifically to provide 2.85 V required to drive a SCSI-2 bus. The output current capability of the regulator is in excess of 800 mA; enough to drive standard SCSI-2, fast SCSI-2, and some wide SCSI-2 applications. The typical dropout voltage is less than 1.0 V, allowing the IC to regulate to input voltages less than 4.0 V. Internal protective features include current and thermal limiting. EE EEE EEEEE EEEEE P.C. Board Heatsink Example 160 L 120 2.0 oz Copper L 9.0 mm L 80 40 0 0 10 20 30 40 50 L, LENGTH OF COPPER FLAGS (mm) 60 70 90 EEEEE EEEEE EEEEE EEEEE P.C. Board Heatsink Example L 80 2.0 oz Copper 70 L 60 50 40 0 Figure 4. SOIC-8 Thermal Resistance versus P.C.B. Copper Length 10 20 30 L, LENGTH OF COPPER (mm) 40 Figure 5. DPAK-3 Thermal Resistance versus P.C.B. Copper Length ORDERING INFORMATION Package Shipping Information SOIC-8 98 Units / Rail MC34268DG SOIC-8 (Pb-Free) 98 Units / Rail MC34268DR2 SOIC-8 2500 Units / Tape & Reel SOIC-8 (Pb-Free) 2500 Units / Tape & Reel DPAK-3 75 Units / Rail DPAK-3 (Pb-Free) 75 Units / Rail Device MC34268D MC34268DR2G MC34268DT MC34268DTG MC34268DTRK DPAK-3 2500 Units / Tape & Reel MC34268DTRKG DPAK-3 (Pb-Free) 2500 Units / Tape & Reel MC34268STT3 SOT-223 4000 Units / Tape & Reel For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. http://onsemi.com 3 MC34268 PACKAGE DIMENSIONS SOIC-8 D SUFFIX CASE 751-07 ISSUE AB -X- NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. 6. 751-01 THRU 751-06 ARE OBSOLETE. NEW STANDARD IS 751-07. A 8 5 S B 1 0.25 (0.010) M Y M 4 -Y- K G C N X 45 _ SEATING PLANE -Z- 0.10 (0.004) H D 0.25 (0.010) M Z Y S X M J S DIM A B C D G H J K M N S SOLDERING FOOTPRINT* 1.52 0.060 7.0 0.275 4.0 0.155 0.6 0.024 1.270 0.050 SCALE 6:1 SOIC-8 mm inches *For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. http://onsemi.com 4 MILLIMETERS MIN MAX 4.80 5.00 3.80 4.00 1.35 1.75 0.33 0.51 1.27 BSC 0.10 0.25 0.19 0.25 0.40 1.27 0_ 8_ 0.25 0.50 5.80 6.20 INCHES MIN MAX 0.189 0.197 0.150 0.157 0.053 0.069 0.013 0.020 0.050 BSC 0.004 0.010 0.007 0.010 0.016 0.050 0_ 8_ 0.010 0.020 0.228 0.244 MC34268 PACKAGE DIMENSIONS DPAK-3 DT SUFFIX CASE 369A-13 ISSUE AB -T- C B V NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. SEATING PLANE E R 4 Z A S 1 2 DIM A B C D E F G H J K L R S U V Z 3 U K F J L H D G 2 PL 0.13 (0.005) M T SOLDERING FOOTPRINT* 6.20 0.244 3.0 0.118 2.58 0.101 5.80 0.228 1.6 0.063 6.172 0.243 SCALE 3:1 mm inches DPAK-3 *For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. http://onsemi.com 5 INCHES MIN MAX 0.235 0.250 0.250 0.265 0.086 0.094 0.027 0.035 0.033 0.040 0.037 0.047 0.180 BSC 0.034 0.040 0.018 0.023 0.102 0.114 0.090 BSC 0.175 0.215 0.020 0.050 0.020 --- 0.030 0.050 0.138 --- MILLIMETERS MIN MAX 5.97 6.35 6.35 6.73 2.19 2.38 0.69 0.88 0.84 1.01 0.94 1.19 4.58 BSC 0.87 1.01 0.46 0.58 2.60 2.89 2.29 BSC 4.45 5.46 0.51 1.27 0.51 --- 0.77 1.27 3.51 --- MC34268 PACKAGE DIMENSIONS SOT-223 ST SUFFIX CASE 318E-04 ISSUE K A F NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 4 S 1 2 INCHES DIM MIN MAX A 0.249 0.263 B 0.130 0.145 C 0.060 0.068 D 0.024 0.035 F 0.115 0.126 G 0.087 0.094 H 0.0008 0.0040 J 0.009 0.014 K 0.060 0.078 L 0.033 0.041 M 0_ 10 _ S 0.264 0.287 B 3 D L G J C 0.08 (0003) M H K MILLIMETERS MIN MAX 6.30 6.70 3.30 3.70 1.50 1.75 0.60 0.89 2.90 3.20 2.20 2.40 0.020 0.100 0.24 0.35 1.50 2.00 0.85 1.05 0_ 10 _ 6.70 7.30 SOLDERING FOOTPRINT* 3.8 0.15 2.0 0.079 2.3 0.091 2.3 0.091 6.3 0.248 2.0 0.079 1.5 0.059 SCALE 6:1 mm inches SOT-23 *For additional information on our Pb-Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. 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