LT1271/LT1269 4A High Efficiency Switching Regulators FEATURES DESCRIPTIOU n Wide Input Voltage Range 3.5V to 30V The LT®1271 and LT1269 are monolithic high power n Low Quiescent Current: 7mA switching regulators. Identical to the popular LT1070, n Internal 4A Switch except for switching frequency (LT1271 = 60kHz, LT1269 n Very Few External Parts Required = 100kHz) and slightly lower switch current, they can be n Self Protected Against Overloads operated in all standard switching configurations includ- n Shutdown Mode Draws Only 100m A Supply Current ing buck, boost, flyback and inverting. A high current, high n Flyback Regulated Mode Has Fully Floating Outputs efficiency switch is included on the die along with all n Comes in Standard 5-Pin Package oscillator, control and protection circuitry. Integration of n Can Be Externally Synchronized (See LT1072 Data Sheet) all functions allows the LT1271/LT1269 to be built in a standard TO-220 power package. This makes them ex- APPLICATIOUS tremely easy to use and provides “bust proof” operation n Boost Converter similar to that obtained with 3-pin linear regulators. n High Efficiency Buck Converter The LT1271/LT1269 operate with supply voltages from n PC Power Supply with Multiple Outputs 3.5V to 30V, and draw only 7mA quiescent current. By n Battery Up-Converter utilizing current mode switching techniques, they pro- n Negative-to-Positive Converter vides excellent AC and DC load and line regulation. USER NOTE: A patented adaptive antisat switch drive allows very wide 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 ranging load currents with no loss in efficiency. An exter- 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 nally activated shutdown mode reduces total supply cur- 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 rent to 100m A typical for standby operation. current rating and higher operating frequency. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. TYPICAL APPLICATIONU High Efficiency 5V Regulator with Burst ModeTM Operation Maximum Output Power 50 6.5V TO 2V5IVN(cid:13) VSW VIN BOOST BUCK-BOOST(cid:13) FBVC LT1271 GND EAFTF1 IINOC4UIE1TN 4=8C 0Y. 4»A 9 T0O% 1(cid:13).5A OWER (W) 3400 FLYBACK†(INVVOE =R 1T2INVG(cid:13)) P 0(cid:13).026m8F0(cid:13)W 0.03m F(cid:13) 4.7m F(cid:13)+ 25Lm1H(cid:13) (cid:13) UTPUT 20 0.1m F(cid:13)(cid:13) (cid:13) TANT(cid:13)(cid:13) TO 50m H 0.015W VOUT(cid:13) O 10 BUVCOK -=B O5VO(cid:13)ST(cid:13) MBR(cid:13) + 5V, 3A (INVERTING) 330pF 390m F(cid:13) 0 16V 0 5 10 15 20 25 30 VC DIODE V+ INPUT VOLTAGE (V) 1271/69 TA02 200Cm 1F(cid:13)(cid:13) + VIN LT1432 VVOLIUMT †(cid:13)BTORUPACTNIKMS MUFOOMRD TMEO EO ARUC TTHPUIUERTVN EPS O FRUWALETLRI OP » OM W(U3ES.5RTA. B)(EV(cid:13)OUT)(cid:13) 35V MODE GND <0.3V = NORMAL RUN MODE(cid:13) >2.5V = SHUTDOWN(cid:13) OPEN = BURST MODE OPERATION 127/691 TA01 1

LT1271/LT1269 ABSOLUTE WAXIWUW RATIUGS Supply Voltage ....................................................... 30V Operating Junction Temperature Range Switch Output Voltage............................................ 60V Operating.............................................. 0(cid:176) C to 100(cid:176) C Feedback Pin Voltage (Transient, 1ms) ................ – 15V Short Circuit......................................... 0(cid:176) C to 125(cid:176) C Storage Temperature Range................ –65(cid:176) C to 150(cid:176) C Lead Temperature (Soldering, 10 sec.)................ 300(cid:176) C PACKAGE/ORDER IUFORWATIOU FRONT VIEW ORDER PART ORDER PART 5(cid:13) VIN(cid:13) NUMBER TOP VIEW NUMBER 4(cid:13) VSW(cid:13) VSW(cid:13) 1(cid:13) 20(cid:13) VSW(cid:13) 3(cid:13) GND(cid:13) LT1271CQ LT1269CS VSW(cid:13) 2(cid:13) 19(cid:13) VSW(cid:13) 2(cid:13) FB(cid:13) LT1269CQ NC(cid:13) 3(cid:13) 18(cid:13) NC(cid:13) 1 VC GND(cid:13) 4(cid:13) 17(cid:13) GND(cid:13) Q PACKAGE(cid:13) 5-LEAD PLASTIC DD POWER(cid:13) GND(cid:13) 5(cid:13) 16(cid:13) GND(cid:13) POWER(cid:13) TJ MAX = 100(cid:176)C, q JC = 4(cid:176)C/W, q JA = 30(cid:176)C/W* SWITCH GND(cid:13) 6(cid:13) 15(cid:13) GND(cid:13) SWITCH GND(cid:13) 7(cid:13) 14(cid:13) GND(cid:13) FRONT VIEW ORDER PART AGND(cid:13) 8(cid:13) 13(cid:13) VIN(cid:13) 5(cid:13) VIN(cid:13) NUMBER VC(cid:13) 9(cid:13) 12(cid:13) NC(cid:13) 4(cid:13) VSW(cid:13) FB 10 11(cid:13) NC 3(cid:13) GND(cid:13) LT1271CT SW PACKAGE(cid:13) (cid:13) 2(cid:13) FB(cid:13) LT1269CT 20-LEAD PLASTIC WIDE S(cid:13)O 1 VC q WILL VARY FROM APPROXIMATELY 40(cid:176)C/W WITH 0.75 SQ. IN. OF 1 OZ. COPPER TO 46(cid:176)C/W T PACKAGE(cid:13) WITH 0.33 SQ. IN. OF 1 OZ. COPPER 5-LEAD PLASTIC TO-220 TJ MAX = 100(cid:176)C, q JC = 4(cid:176)C/W, q JA = 50(cid:176)C/W *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 V = 15V, V = 0.5V, V = V switch pin open, unless otherwise noted. IN C FB REF, SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Reference Voltage Measured at Feedback Pin 1.224 1.244 1.264 V REF V = 0.8V l 1.214 1.244 1.274 V C I Feedback Input Current V = V 350 750 nA B FB REF l 1100 nA gm Error Amplifier D I = – 25m A 3000 4400 6000 m mho C Transconductance l 2400 7000 m mho Error Amplifier Source or V = 1.5V 150 200 350 m A C Sink Current l 120 400 m A Error Amplifier Clamp Hi Clamp, V = 1V 1.8 2.3 V FB Voltage Lo Clamp, V = 1.5V 0.25 0.38 0.52 V FB Reference Voltage Line 3V £ V £ V V = 0.8V l 0.03 %/V IN MAX, C Regulation A Error Amplifier Voltage Gain 0.9V £ V £ 1.4V 500 800 V/V V C Minimum Input Voltage (Note 3) l 2.8 3.0 V I Supply Current 3V £ V £ V , V = 0.6V 7 10 mA Q IN MAX C 2

LT1271/LT1269 ELECTRICAL CHARACTERISTICS V = 15V, V = 0.5V, V = V switch pin open, unless otherwise noted. IN C FB REF, SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Control Pin Threshold Duty Cycle = 0 0.7 0.9 1.08 V l 0.5 1.25 V Normal/Flyback Threshold 0.4 0.45 0.54 V on Feedback Pin V Flyback Reference Voltage I = 50m A 15 16.3 17.6 V FB FB l 14 18 V V Change in Flyback 0.05 £ I £ 1mA 4.5 6.8 8.5 V FB FB Reference Voltage Flyback Reference Voltage I = 50m A 0.01 0.03 %/V FB Line Regulation 3V £ V £ V IN MAX Flyback Amplifier D I = – 10m A 150 300 650 m mho C Transconductance (gm) Flyback Amplifier Source V = 0.6V Source l 15 32 70 m A C and Sink Current I = 50m A Sink l 25 40 70 m A FB BV Output Switch Breakdown 3V £ V £ V l 60 75 V IN MAX Voltage I = 1.5mA SW V Output Switch (Note 1) l 0.2 0.33 W SAT “On” Resistance Control Voltage to Switch 6.4 A/V Current Transconductance I Switch Current Limit (Note 2) Duty Cycle = 50% l 4 8 A LIM Duty Cycle = 80% l 3.2 8 A D I Supply Current Increase 25 40 mA/A IN D I During Switch On-Time SW f Switching Frequency LT1271 l 50 60 70 kHz LT1269 l 85 100 115 kHz DC (max) Maximum Switch Duty Cycle LT1271 85 92 95 % LT1269 80 90 95 % Flyback Sense Delay Time 1.5 m s Shutdown Mode 3V £ V £ V , V = 0.05V 100 400 m A IN MAX C Supply Current Shutdown Mode 3V £ V £ V 100 150 250 mV IN MAX Threshold Voltage l 50 300 mV The l denotes the specifications which apply over the full operating Note 2: For duty cycles (DC) between 50% and 85%, minimum temperature range. guaranteed switch current is given by I = 2.67 (2 – DC). LIM Note 1: Measured with V in hi clamp, V = 0.8V. Note 3: Minimum input voltage. C FB 3

LT1271/LT1269 TYPICAL PERFORWAUCE CHARACTERISTICS Switch Current Limit vs Duty Cycle Switch Saturation Voltage 12 1.6 TJ = 25°C V) 1.4 E ( 9 G 1.2 A) TA NT ( VOL 1.0 URRE 6 –55°C 25°C TION 0.8 C A WITCH 125°C SATUR 0.6 S 3 CH 0.4 T WI S 0.2 0 0 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 DUTY CYCLE (%) SWITCH CURRENT (A) 1271/69 G01 1271/69 G02 TYPICAL APPLICATIOUS Negative-to-Positive Buck-Boost Converter L2 L1**(cid:13) OPTIONAL(cid:13) C3 100m H OUTPUT(cid:13) FILTER D1(cid:13) MBR340 VIN VSW + · 1V2OVU,T (cid:13)1.5A + C2(cid:13) R1(cid:13) C4*(cid:13) LT1271 200m F(cid:13) 11.3k 200m F(cid:13) (cid:13) Q1(cid:13) (cid:13) 2N3906 OPTIONAL(cid:13) INTPUT(cid:13) GND VC FB FILTER R3(cid:13) R2(cid:13) 2.2k 1.24k L3 C1(cid:13) * REQUIRED IF INPUT LEADS ‡ 2"(cid:13) –1V2IVN(cid:13) · 0(cid:13) .22m F(cid:13) ** COILTRONICS CTX100-2-52 1271/69 TA04 4

LT1271/LT1269 TYPICAL APPLICATIOUS Boost Converter (5V to 12V) 5V 100m H* VIN VSW MBR330 LT1271 12V(cid:13) 0.5A 10.7k + GND VC FB 100m F(cid:13) 25V(cid:13) (cid:13) 1k 1.24k 1m F(cid:13) (cid:13) * COILTRONICS CTX100-2-52 1271/69 TA03 PACKAGE DESCRIPTIOU Dimensions in inches (millimeters) unless otherwise noted. Q Package 5-Lead Plastic DD Pak (LTC DWG # 05-08-1461) 0.060(cid:13) (1.524)(cid:13) 0.390 – 0.415(cid:13) 0.256(cid:13) 0.060(cid:13) TYP (9.906 – 10.541) 0.165 – 0.180(cid:13) (6.502) (1.524) (4.191 – 4.572) 0.045 – 0.055(cid:13) 15° TYP (1.143 – 1.397) +0.008(cid:13) 0.004 0.060(cid:13) 0.183(cid:13) 0.330 – 0.370(cid:13) 0.059(cid:13) ( –0.004) (1.524) (4.648) (1.499)(cid:13) +0.203(cid:13) (8.382 – 9.398) 0.102 TYP –0.102 0.095 – 0.115(cid:13) (2.413 – 2.921) 0.075(cid:13) (1.905) (07..360200(cid:13)) (0.143+–00..001220(cid:13)) (01..045477 –– 01..097575(cid:13)) (00..031330 –– 00..052834(cid:13)) (01..025700 –– 00..031025(cid:13)) 0.028 – 0.038(cid:13) BOTTOM VIEW OF DD PAK(cid:13) 3.632+–00..350058(cid:13) (0.711 – 0.965) HATCHED AREA IS SOLDER PLATED(cid:13) Q(DD5) 0396 COPPER HEAT SINK 5

LT1271/LT1269 PACKAGE DESCRIPTIOU Dimensions in inches (millimeters) unless otherwise noted. T Package 5-Lead Plastic TO-220 (Standard) (LTC DWG # 05-08-1421) 0.147 – 0.155(cid:13) 0.165 – 0.180(cid:13) 0.390 – 0.415(cid:13) (3.734 – 3.937)(cid:13) (4.191 – 4.572) 0.045 – 0.055(cid:13) (9.906 – 10.541) DIA (1.143 – 1.397) 0.230 – 0.270(cid:13) (5.842 – 6.858) 0.570 – 0.620(cid:13) 0.620(cid:13) 0.460 – 0.500(cid:13) (14.478 – 15.748) (15.75)(cid:13) (11.684 – 12.700) 0.330 – 0.370(cid:13) TYP(cid:13) (8.382 – 9.398) 0.700 – 0.728(cid:13) (cid:13) (17.78 – 18.491)(cid:13) (cid:13) 0.095 – 0.115 (cid:13) 0.152 – 0.202(cid:13) (2.413 – 2.921) 0.260 – 0.320(cid:13) (3.861 – 5.131)(cid:13) (6.60 – 8.13)(cid:13) (cid:13) (cid:13) 0.013 – 0.023(cid:13) (0.330 – 0.584) 0.057 – 0.077(cid:13) 0.028 – 0.038(cid:13) 0.135 – 0.165(cid:13) 0.155 – 0.195(cid:13) (1.448 – 1.956) (0.711 – 0.965) (3.429 – 4.191) (3.937 – 4.953) T5 (TO-220) 0398(cid:3) (cid:13) 6

LT1271/LT1269 PACKAGE DESCRIPTIOU 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*(cid:13) (12.598 – 13.005) 20 19 18 17 16 15 14 13 12 11 NOTE 1 0.394 – 0.419(cid:13) (10.007 – 10.643) 0.291 – 0.299**(cid:13) 1 2 3 4 5 6 7 8 9 10 (7.391 – 7.595) 0.093 – 0.104(cid:13) 0.037 – 0.045(cid:13) 0.010 – 0.029(cid:13) · 45(cid:176) (2.362 – 2.642) (0.940 – 1.143) (0.254 – 0.737) 0° – 8° TYP 0.050(cid:13) 0.009 – 0.013(cid:13) (1.270)(cid:13) 0.004 – 0.012(cid:13) (0.229 – 0.330) NOTE 1 TYP (0.102 – 0.305) 0.016 – 0.050(cid:13) 0.014 – 0.019(cid:13) (0.406 – 1.270) (0.356 – 0.482)(cid:13) S20 (WIDE) 0396 TYP NOTE:(cid:13) 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.(cid:13) THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS *(cid:13)DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE(cid:13) **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE(cid:13) (cid:13) (cid:13) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 7 However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LT1271/LT1269 TYPICAL APPLICATIONU Negative Buck Converter + D1(cid:13) C2(cid:13) MBR735 100m F(cid:13) (cid:13) L1**(cid:13) R1(cid:13) LOAD VIN VSW 100m H 4.64·k –5.2V AT 3.5A + C3*(cid:13) LT1271 12k 100m F Q1(cid:13) 2N3906 OPTIONAL(cid:13) IFNILTTPEURT(cid:13) GND VC FB OPTIONAL(cid:13) + L3(cid:13) C1 OFUILTTPEURT(cid:13) C2040(cid:13) m F 10m H R3 R2(cid:13) L2(cid:13) 1.24k 4m H VIN(cid:13) · –8V TO –30V * REQUIRED IF INPUT LEADS ‡ 2"(cid:13) ** COILTRONICS CTX100-2-52 1271/69 TA05 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1171 100kHz, 2.5A Boost Switching Regulator Good for V Up to 40V IN 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 V Up to 25V, SO-8 Package IN LT1376 500kHz, 1.5A Buck Switching Regulator V Up to 25V, Uses 4.7m H Inductor IN 8 Linear Technology Corporation 127169fb LT/TP 0798 2K REV B • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l w ww.linear-tech.com ª LINEAR TECHNOLOGY CORPORATION 1992