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| LT1271/LT1269 4A High Efficiency Switching Regulators FEATURES s s DESCRIPTIO Wide Input Voltage Range 3.5V to 30V The LT1271 and LT1269 are monolithic high power switchLow Quiescent Current: 7mA ing regulators. Identical to the popular LT1070, except for s Internal 4A Switch switching frequency (LT1271 = 60kHz, LT1269 = 100kHz) s Very Few External Parts Required and slightly lower switch current, they can be operated in s Self Protected Against Overloads all standard switching configurations including buck, boost, s Shutdown Mode Draws Only 100A Supply Current flyback, and inverting. A high current, high efficiency s Flyback Regulated Mode Has Fully Floating Outputs switch is included on the die along with all oscillator, s Comes in Standard 5-Pin Package control, and protection circuitry. Integration of all funcs Can Be Externally Synchronized (See LT1072 Data Sheet) tions allows the LT1271/LT1269 to be built in a standard TO-220 power package. This makes them extremely easy APPLICATI S to use and provides "bust proof" operation similar to that s Boost Converter obtained with 3-pin linear regulators. s High Efficiency Buck Converter The LT1271/LT1269 operate with supply voltages from s PC Power Supply with Multiple Outputs 3.5V to 30V, and draw only 7mA quiescent current. By s Battery Up-Converter utilizing current mode switching techniques, they pros Negative-to-Positive Converter vides excellent AC and DC load and line regulation. USER NOTE: This data sheet is only intended to provide specifications, graphs, and a general functional description of the LT1271/LT1269. Application circuits are included to show the capability of the LT1271/LT1269. A complete design manual (AN-19) should be obtained to assist in developing new designs. This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1271/LT1269 by factoring in the higher switch current rating and higher operating frequency. A patented adaptive anti-sat switch drive allows very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100A typical for standby operation. High Efficiency 5V Regulator with Burst Mode VIN 6.5V TO 25V VSW LT1271 FB VC 0.02F 680 0.1F 0.03F VIN 50 EFFICIENCY 90% AT IOUT = 0.4A TO 1.5A 1N4148 OUTPUT POWER (W) GND BOOST BUCK-BOOST VO = 12V (INVERTING) FLYBACK 40 + 4.7F TANT L1 25H TO 50H 0.015 VOUT 5V, 3A 30 20 BUCK-BOOST VO = 5V (INVERTING) 0 5 15 20 10 INPUT VOLTAGE (V) 25 30 MBR 330pF VC C1 200F 35V DIODE LT1432 VOUT MODE GND V+ VLIM + 390F 16V 10 + VIN <0.3V = NORMAL RUN MODE >2.5V = SHUTDOWN OPEN = BURST MODE LT1271 TA01 U Maximum Output Power 0 BUCK MODE OUTPUT POWER (3.5A)(VOUT) TRANSFORMER TURNS RATIO MUST BE LT1271 TA02 OPTIMUM TO ACHIEVE FULL POWER. UO 1 LT1271/LT1269 ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO FRONT VIEW 5 4 3 2 1 T PACKAGE 5-LEAD TO-220 VIN VSW GND FB VC Supply Voltage ....................................................... 30V Switch Output Voltage ............................................ 60V Feedback Pin Voltage (Transient, 1ms) ................ 15V Operating Junction Temperature Range (Oper.) ................................................ 0C to +100C (Short Ckt.)......................................... 0C to +125C Storage Temperature Range .............. - 65C to +150C Lead Temperature (Soldering, 10 sec.)................ 300C FRONT VIEW 5 4 3 2 1 Q PACKAGE 5-LEAD DD VIN VSW GND FB VC TJ MAX = 100C, JC = 4C/W, JA = 50C/W TJ MAX = 100C, JC = 4C/W JA = 30C/W* ORDER PART NUMBER LT1271CT LT1269CT ground plane. LT1271CQ LT1269CQ *With device soldered to 1/2 square inch of 1oz copper over backside or internal layer ELECTRICAL CHARACTERISTICS SYMBOL VREF IB gm PARAMETER Reference Voltage Feedback Input Current Error Amplifier Transconductance Error Amplifier Source or Sink Current Error Amplifier Clamp Voltage Reference Voltage Line Regulation AV IQ Error Amplifier Voltage Gain Minimum Input Voltage (Note 3) Supply Current Control Pin Threshold Normal/Flyback Threshold on Feedback Pin VFB VFB Flyback Reference Voltage Change in Flyback Reference Voltage Flyback Reference Voltage Line Regulation Flyback Amplifier Transconductance (gm) Flyback Amplifier Source and Sink Current VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted. MIN q q CONDITIONS Measured at Feedback Pin VC = 0.8V VFB = VREF IC = 25A q TYP 1.244 1.244 350 MAX 1.264 1.274 750 1100 6000 7000 350 400 2.3 0.52 0.03 UNITS V V nA nA mho mho A A V V %/V V/V 1.224 1.214 3000 2400 150 120 1.8 0.25 4400 200 VC = 1.5V q Hi Clamp, VFB = 1V Lo Clamp, VFB = 1.5V 3V VIN VMAX, VC = 0.8V 0.9V VC 1.4V q q 0.38 500 800 2.8 7 3.0 10 1.08 1.25 0.54 17.6 18 8.5 0.03 650 70 70 3V VIN VMAX, VC = 0.6V Duty Cycle = 0 q 0.7 0.5 0.4 0.9 0.45 16.3 6.8 0.01 IFB = 50A q 15 14 4.5 0.05 IFB 1mA IFB = 50A 3V VIN VMAX IC = 10A VC = 0.6V IFB = 50A Source Sink q q 150 15 25 300 32 40 mho A A 2 U V mA V V V V V V %/V W U U WW W LT1271/LT1269 ELECTRICAL CHARACTERISTICS SYMBOL BV VSAT PARAMETER Output Switch Breakdown Voltage Output Switch (Note 1) "On" Resistance Control Voltage to Switch Current Transconductance ILIM IIN ISW f DC (max) Switch Current Limit (Note 2) Supply Current Increase During Switch On-Time Switching Frequency Maximum Switch Duty Cycle Flyback Sense Delay Time Shutdown Mode Supply Current Shutdown Mode Threshold Voltage LT1271 LT1269 LT1271 LT1269 VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted. MIN q q CONDITIONS 3V VIN VMAX ISW = 1.5mA TYP 75 0.2 6.4 MAX UNITS V 60 0.33 A/V Duty Cycle = 50% Duty Cycle = 80% q q 4 3.2 25 8 8 40 70 115 95 95 400 250 300 A A mA/A kHz kHz % % s A mV mV q q 50 85 85 80 60 100 92 90 1.5 100 3V VIN VMAX, VC = 0.05V 3V VIN VMAX q 100 50 150 The q denotes the specifications which apply over the full operating temperature range. Note 1: Measured with VC in hi clamp, VFB = 0.8V. Note 2: For duty cycles (DC) between 50% and 85%, minimum guaranteed switch current is given by ILIM = 2.67 (2 - DC). Note 3: Minimum input voltage. TYPICAL PERFOR A CE CHARACTERISTICS Switch Current Limit vs Duty Cycle 12 SWITCH SATURATION VOLTAGE (V) SWITCH CURRENT (A) 9 -55C 6 125C 3 0 0 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%) LT1271 G01 UW Switch Saturation Voltage 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5 LT1271 G02 TJ = 25C 25C SWITCH CURRENT (A) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 3 LT1271/LT1269 TYPICAL APPLICATI Negative-to-Positive Buck-Boost Converter L2 L1 100H** D1 MBR340 VSW C2 200F OPTIONAL OUTPUT FILTER C3 5V 100H* VIN C4 200F* OPTIONAL INTPUT FILTER L3 VIN -12V + LT1271 GND x C3 100F* OPTIONAL INTPUT FILTER L3 10H VIN -8V TO -30V PACKAGE DESCRIPTIO T Package 5-Lead TO-220 0.380 - 0.420 (9.652 - 10.668) 0.139 - 0.153 (3.531 - 3.886) DIA 0.079 - 0.135 (2.007 - 3.429) 0.169 - 0.185 (4.293 - 4.699) 0.560 - 0.650 (14.224 - 16.510) 0.866 - 0.913 (21.996 - 23.190) 0.460 - 0.500 (11.68 - 12.70) 0.970 - 1.050 (24.64 - 26.67) 0.057 - 0.077 (1.448 - 1.956) 0.015 - 0.025 (0.381 - 0.635) 0.210 - 0.240 (5.334 - 6.096) 0.028 - 0.035 (0.711 - 0.889) 0.327 - 0.335 (8.306 - 8.509) 4 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7487 (408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977 U UO VC S Boost Converter (5V to 12V) + x VIN VOUT 12V, 1.5A R1 11.3k LT1271 VSW MBR330 12V 0.5A 10.7k FB 1k Q1 2N3906 FB R3 2.2k C1 0.22F R2 1.24k * REQUIRED IF INPUT LEADS 2" ** COILTRONICS CTX100-2-52 LT1271 TA04 GND VC + - 1.24k 100F 25V + - + 1F - * COILTRONICS CTX100-2-52 LT1271 TA03 Negative Buck Converter D1 MBR735 C2 100F L1 100H** VSW + R1 4.64k LOAD -5.2V AT 3.5A 12k VIN x + LT1271 Q1 2N3906 VC FB C1 R3 R2 1.24k OPTIONAL OUTPUT FILTER L2 4H GND + C4 200F x * REQUIRED IF INPUT LEADS 2" ** COILTRONICS CTX100-2-52 LT1271 TA05 Dimensions in inches (millimeters) unless otherwise noted. Q Package 5-Lead DD 0.035 - 0.055 (0.889 - 1.397) 0.060 (1.524) TYP 0.401 0.015 (10.185 0.381) 0.175 0.08 (4.445 0.203) 15 TYP 0.050 0.08 (1.270 0.203) 0.620 0.020 (15.75 0.508) 0.700 - 0.728 (17.780 - 18.491) ( +0.012 0.331 -0.020 +0.305 8.407 -0.508 ) 0.067 0.010 (1.702 0.254) 0.032 0.008 (0.813 0.203) 0.059 (1.499) TYP ( +0.008 0.004 -0.004 +0.203 0.102 -0.102 ) 0.105 0.008 (2.667 0.203) 0.055 - 0.090 (1.397 - 2.286) 0.079 - 0.115 (2.007 - 2.921) 0.170 - 0.185 (4.318 - 4.699) T5 0392 ( +0.012 0.143 -0.020 +0.305 3.632 -0.508 ) 0.022 0.005 (0.559 0.127) 0.050 0.012 (1.270 0.305) Q5 0592 LT/GP 10393 15K REV A (c) LINEAR TECHNOLOGY CORPORATION 1992 |
Price & Availability of LT1271
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