LT1271/LT1269 4A High Efficiency Switching Regulators U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ Wide Input Voltage Range 3.5V to 30V Low Quiescent Current: 7mA Internal 4A Switch Very Few External Parts Required Self Protected Against Overloads Shutdown Mode Draws Only 100µA Supply Current Flyback Regulated Mode Has Fully Floating Outputs Comes in Standard 5-Pin Package Can Be Externally Synchronized (See LT1072 Data Sheet) UO APPLICATI ■ ■ ■ ■ ■ S Boost Converter High Efficiency Buck Converter PC Power Supply with Multiple Outputs Battery Up-Converter Negative-to-Positive Converter The LT®1271 and LT1269 are monolithic high power switching regulators. Identical to the popular LT1070, except for switching frequency (LT1271 = 60kHz, LT1269 = 100kHz) and slightly lower switch current, they can be operated in all standard switching configurations including buck, boost, flyback and inverting. A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1271/LT1269 to be built in a standard TO-220 power package. This makes them extremely easy to use and provides “bust proof” operation similar to that obtained with 3-pin linear regulators. The LT1271/LT1269 operate with supply voltages from 3.5V to 30V, and draw only 7mA quiescent current. By utilizing current mode switching techniques, they provides 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 antisat switch drive allows very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 100µA typical for standby operation. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. U TYPICAL APPLICATION High Efficiency 5V Regulator with Burst ModeTM Operation Maximum Output Power 50 VSW VIN FB VC GND 1N4148 0.02µF 680Ω 0.03µF 4.7µF TANT 0.1µF + L1 25µH TO 50µH MBR 330pF VC C1 200µF 35V + DIODE 0.015Ω + VOUT 5V, 3A 390µF 16V 30 BUCK-BOOST VO = 12V (INVERTING) FLYBACK† 20 BUCK-BOOST VO = 5V (INVERTING) 10 0 0 V+ 5 15 20 10 INPUT VOLTAGE (V) 25 30 1271/69 TA02 VLIM VIN LT1432 † VOUT MODE BOOST 40 EFFICIENCY ≈ 90% AT IOUT = 0.4A TO 1.5A LT1271 OUTPUT POWER (W) VIN 6.5V TO 25V BUCK MODE OUTPUT POWER ≈ (3.5A)(VOUT) TRANSFORMER TURNS RATIO MUST BE OPTIMUM TO ACHIEVE FULL POWER. GND < 0.3V = NORMAL RUN MODE > 2.5V = SHUTDOWN OPEN = BURST MODE OPERATION 127/691 TA01 1 LT1271/LT1269 W W W AXI U U ABSOLUTE RATI GS Supply Voltage ....................................................... 30V Switch Output Voltage ............................................ 60V Feedback Pin Voltage (Transient, 1ms) ................ ±15V Storage Temperature Range ................ – 65°C to 150°C Operating Junction Temperature Range Operating .............................................. 0°C to 100°C Short Circuit ......................................... 0°C to 125°C Lead Temperature (Soldering, 10 sec.)................ 300°C W U U PACKAGE/ORDER I FOR ATIO ORDER PART NUMBER FRONT VIEW 5 VIN 4 VSW 3 GND 2 FB 1 VC TOP VIEW LT1271CQ LT1269CQ Q PACKAGE 5-LEAD PLASTIC DD TJ MAX = 100°C, θJC = 4°C/W, θJA = 30°C/W* POWER SWITCH FRONT VIEW 5 VIN 4 VSW 3 GND 2 FB 1 VC ORDER PART NUMBER ORDER PART NUMBER LT1271CT LT1269CT T PACKAGE 5-LEAD PLASTIC TO-220 TJ MAX = 100°C, θJC = 4°C/W, θJA = 50°C/W VSW 1 20 VSW VSW 2 19 VSW NC 3 18 NC GND 4 17 GND GND 5 16 GND GND 6 15 GND GND 7 14 GND AGND 8 13 VIN VC 9 12 NC FB 10 11 NC LT1269CS POWER SWITCH SW PACKAGE 20-LEAD PLASTIC WIDE SO θ WILL VARY FROM APPROXIMATELY 40°C/W WITH 0.75 SQ. IN. OF 1 OZ. COPPER TO 46°C/W WITH 0.33 SQ. IN. OF 1 OZ. COPPER *With device soldered to 1/2 square inch of 1oz copper over backside or internal layer ground plane. Consult factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VREF Reference Voltage Measured at Feedback Pin VC = 0.8V 1.224 1.214 1.244 1.244 1.264 1.274 V V 350 750 1100 nA nA IB Feedback Input Current ● VFB = VREF ● gm AV Error Amplifier Transconductance ∆IC = ±25µA Error Amplifier Source or Sink Current VC = 1.5V Error Amplifier Clamp Voltage Hi Clamp, VFB = 1V Lo Clamp, VFB = 1.5V Reference Voltage Line Regulation 3V ≤ VIN ≤ VMAX, VC = 0.8V Error Amplifier Voltage Gain 0.9V ≤ VC ≤ 1.4V Minimum Input Voltage (Note 3) IQ 2 Supply Current 3000 2400 4400 ● 6000 7000 µmho µmho 150 120 200 ● 350 400 µA µA 2.3 0.52 V V 0.03 %/V 1.8 0.25 ● 500 ● 3V ≤ VIN ≤ VMAX, VC = 0.6V 0.38 800 V/V 2.8 3.0 V 7 10 mA LT1271/LT1269 ELECTRICAL CHARACTERISTICS SYMBOL VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted. PARAMETER CONDITIONS Control Pin Threshold Duty Cycle = 0 MIN TYP MAX UNITS 0.7 0.5 0.9 1.08 1.25 V V 0.4 0.45 0.54 V 15 14 16.3 17.6 18 V V 4.5 6.8 8.5 V 0.01 0.03 %/V 150 300 650 µmho ● ● 15 25 32 40 70 70 µA µA ● 60 75 ● Normal/Flyback Threshold on Feedback Pin VFB Flyback Reference Voltage IFB = 50µA ● Change in Flyback Reference Voltage 0.05 ≤ IFB ≤ 1mA Flyback Reference Voltage Line Regulation IFB = 50µA 3V ≤ VIN ≤ VMAX Flyback Amplifier Transconductance (gm) ∆IC = ±10µA Flyback Amplifier Source and Sink Current VC = 0.6V IFB = 50µA BV Output Switch Breakdown Voltage 3V ≤ VIN ≤ VMAX ISW = 1.5mA VSAT Output Switch (Note 1) “On” Resistance VFB Source Sink 0.2 ● Control Voltage to Switch Current Transconductance V 0.33 6.4 ILIM Switch Current Limit (Note 2) Duty Cycle = 50% Duty Cycle = 80% ∆IIN ∆ISW Supply Current Increase During Switch On-Time f Switching Frequency LT1271 LT1269 DC (max) Maximum Switch Duty Cycle LT1271 LT1269 ● ● ● ● 4 3.2 A/V 8 8 A A 25 40 mA/A 50 85 60 100 70 115 kHz kHz 85 80 92 90 95 95 % % Flyback Sense Delay Time µs 1.5 Shutdown Mode Supply Current 3V ≤ VIN ≤ VMAX, VC = 0.05V Shutdown Mode Threshold Voltage 3V ≤ VIN ≤ VMAX The ● denotes the specifications which apply over the full operating temperature range. Note 1: Measured with VC in hi clamp, VFB = 0.8V. ● Ω 100 50 100 400 µA 150 250 300 mV mV 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. 3 LT1271/LT1269 U W TYPICAL PERFOR A CE CHARACTERISTICS Switch Current Limit vs Duty Cycle Switch Saturation Voltage 1.6 SWITCH SATURATION VOLTAGE (V) SWITCH CURRENT (A) 12 9 –55°C 25°C 6 125°C 3 0 TJ = 25°C 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%) 0 1 2 3 1271/69 G02 UO S Negative-to-Positive Buck-Boost Converter L2 L1** 100µH OPTIONAL INTPUT FILTER VSW C2 200µF LT1271 VC × × VOUT 12V, 1.5A R1 11.3k FB R3 2.2k VIN –12V + C3 Q1 2N3906 GND L3 4 + OPTIONAL OUTPUT FILTER D1 MBR340 VIN C4* 200µF 5 SWITCH CURRENT (A) 1271/69 G01 TYPICAL APPLICATI 4 C1 0.22µF R2 1.24k * REQUIRED IF INPUT LEADS ≥ 2" ** COILTRONICS CTX100-2-52 1271/69 TA04 LT1271/LT1269 UO TYPICAL APPLICATI S Boost Converter (5V to 12V) 5V 100µH* VIN VSW MBR330 12V 0.5A LT1271 10.7k + FB VC GND 1k 100µF 25V 1.24k 1µF * COILTRONICS CTX100-2-52 U PACKAGE DESCRIPTIO 1271/69 TA03 Dimensions in inches (millimeters) unless otherwise noted. Q Package 5-Lead Plastic DD Pak (LTC DWG # 05-08-1461) 0.256 (6.502) 0.060 (1.524) 0.060 (1.524) TYP 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.572) 15° TYP 0.060 (1.524) 0.183 (4.648) 0.059 (1.499) TYP 0.330 – 0.370 (8.382 – 9.398) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK ( +0.008 0.004 –0.004 +0.203 0.102 –0.102 ) 0.095 – 0.115 (2.413 – 2.921) 0.075 (1.905) 0.300 (7.620) 0.045 – 0.055 (1.143 – 1.397) ( +0.012 0.143 –0.020 +0.305 3.632 –0.508 ) 0.057 – 0.077 (1.447 – 1.955) 0.028 – 0.038 (0.711 – 0.965) 0.013 – 0.023 (0.330 – 0.584) 0.050 ± 0.012 (1.270 ± 0.305) Q(DD5) 0396 5 LT1271/LT1269 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. T Package 5-Lead Plastic TO-220 (Standard) (LTC DWG # 05-08-1421) 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.572) 0.147 – 0.155 (3.734 – 3.937) DIA 0.045 – 0.055 (1.143 – 1.397) 0.230 – 0.270 (5.842 – 6.858) 0.460 – 0.500 (11.684 – 12.700) 0.570 – 0.620 (14.478 – 15.748) 0.330 – 0.370 (8.382 – 9.398) 0.620 (15.75) TYP 0.700 – 0.728 (17.78 – 18.491) 0.152 – 0.202 0.260 – 0.320 (3.861 – 5.131) (6.60 – 8.13) 0.095 – 0.115 (2.413 – 2.921) 0.013 – 0.023 (0.330 – 0.584) 0.057 – 0.077 (1.448 – 1.956) 0.028 – 0.038 (0.711 – 0.965) 0.135 – 0.165 (3.429 – 4.191) 0.155 – 0.195 (3.937 – 4.953) T5 (TO-220) 0398 6 LT1271/LT1269 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. SW Package 20-Lead Plastic Small Outline (Wide 0.300) (LTC DWG # 05-08-1620) 0.496 – 0.512* (12.598 – 13.005) 20 19 18 17 16 15 14 13 12 11 0.394 – 0.419 (10.007 – 10.643) NOTE 1 0.291 – 0.299** (7.391 – 7.595) 0.010 – 0.029 × 45° (0.254 – 0.737) 1 2 3 4 5 6 7 8 9 0.093 – 0.104 (2.362 – 2.642) 10 0.037 – 0.045 (0.940 – 1.143) 0° – 8° TYP 0.009 – 0.013 (0.229 – 0.330) NOTE 1 0.016 – 0.050 (0.406 – 1.270) 0.050 (1.270) TYP 0.014 – 0.019 (0.356 – 0.482) TYP 0.004 – 0.012 (0.102 – 0.305) S20 (WIDE) 0396 NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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. 7 LT1271/LT1269 U TYPICAL APPLICATION Negative Buck Converter D1 MBR735 + OPTIONAL INTPUT FILTER VIN –8V TO –30V × VC 12k FB R3 × –5.2V AT 3.5A Q1 2N3906 OPTIONAL OUTPUT FILTER C1 L3 10µH LOAD R1 4.64k VSW LT1271 GND + L1** 100µH VIN C3* 100µF C2 100µF R2 1.24k + C4 200µF L2 4µH * REQUIRED IF INPUT LEADS ≥ 2" ** COILTRONICS CTX100-2-52 1271/69 TA05 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1171 100kHz, 2.5A Boost Switching Regulator Good for VIN Up to 40V LT1370 500kHz, 6A Boost Switching Regulator 6A, 42V Internal Switch LT1371 500kHz, 3A Boost Switching Regulator 3A, 42V Internal Switch, 90% Efficiency LT1372 500kHz, 1.5A Boost Switching Regulator Also Regulates Negative Flyback Outputs LT1374 500kHz, 4.5A Buck Switching Regulator VIN Up to 25V, SO-8 Package LT1376 500kHz, 1.5A Buck Switching Regulator VIN Up to 25V, Uses 4.7µH Inductor 8 Linear Technology Corporation 127169fb LT/TP 0798 2K REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1992