LT1370 500kHz High Efficiency 6A Switching Regulator DESCRIPTION FEATURES Faster Switching with Increased Efficiency The LT 1370 is a monolithic high frequency current mode Uses Small Inductors: 4.7H switching regulator. It can be operated in all standard All Surface Mount Components switching configurations including boost, buck, flyback, Low Minimum Supply Voltage: 2.7V forward, inverting and Cuk. A 6A high efficiency switch Quiescent Current: 4.5mA Typ is included on the die, along with all oscillator, control and Current Limited Power Switch: 6A protection circuitry. Regulates Positive or Negative Outputs The LT1370 typically consumes only 4.5mA quiescent Shutdown Supply Current: 12A Typ current and has higher efficiency than previous parts. Easy External Synchronization High frequency switching allows for very small inductors Switch Resistance: 0.065 Typ to be used. U New design techniques increase flexibility and maintain APPLICATIONS ease of use. Switching is easily synchronized to an exter- nal logic level source. A logic low on the Shutdown pin Boost Regulators reduces supply current to 12A. Unique error amplifier Laptop Computer Supplies circuitry can regulate positive or negative output voltage Multiple Output Flyback Supplies while maintaining simple frequency compensation tech- Inverting Supplies niques. Nonlinear error amplifier transconductance reduces output overshoot on start-up or overload recov- ery. Oscillator frequency shifting protects external com- ponents during overload conditions. , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATION 5V to 12V Boost Converter 12V Output Efficiency 92 D1 5V V = 5V IN MBRD835L L1* L = 10H V OUT 90 12V V R1 IN 53.6k 88 ON V S/S SW OFF 1% LT1370 86 C4** *COILTRONICS + C1** + FB 22F UP2-4R7 (4.7H) 22F 25V GND V UP4-100 (10H) 84 25V C 2 ** R2 AVX TPSD226M025R0200 6.19k MAX I OUT 82 C2 1% 0.047F L1 I OUT R3 C3 4.7H 1.8A 80 2k 0.0047F 10H 2A 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 LT1370 TA01 LOAD CURRENT (A) LT1370 TA02 sn1370 1370fs 1 EFFICIENCY (%) U ULT1370 ABSOLUTEXAI U RATI GS Supply Voltage ....................................................... 30V Operating Ambient Temperature Range ...... 0C to 70C Switch Voltage Operating Junction Temperature Range LT1370 ............................................................... 35V Commercial .......................................... 0C to 125C LT1370HV .......................................................... 42V Industrial ......................................... 40C to 125C S/S, SHDN, SYNC Pin Voltage ................................ 30V Storage Temperature Range ................ 65C to 150C Feedback Pin Voltage (Transient, 10ms) .............. 10V Lead Temperature (Soldering, 10 sec)................. 300C Feedback Pin Current........................................... 10mA Negative Feedback Pin Voltage (Transient, 10ms) ............................................. 10V PACKAGE/ORDER I FOR ATIO FRONT VIEW ORDER PART FRONT VIEW ORDER PART 7 V IN NUMBER NUMBER 7 V IN 6 NFB 6 NFB TAB 5 V SW TAB 5 V SW IS 4 GND LT1370CT7 LT1370CR IS 4 GND GND 3 S/S GND 3 S/S 2 FB LT1370HVCR LT1370HVCT7 2 FB 1 V C 1 V C LT1370IT7 LT1370IR R PACKAGE LT1370HVIR T7 PACKAGE LT1370HVIT7 7-LEAD PLASTIC DD 7-LEAD TO-220 T = 125C, = 30C/W, = 4C/W JMAX JA JC T = 125C, = 50C/W, = 4C/W JMAX JA JC 2 WITH PACKAGE SOLDERED TO 0.5 INCH COPPER AREA OVER BACKSIDE GROUND PLANE OR INTERNAL CAN VARY FROM 20C/W TO POWER PLANE. JA >40C/W DEPENDING ON MOUNTING TECHNIQUE Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS V = 5V, V = 0.6V, V = V , V , S/S and NFB pins open, T = 25C unless otherwise noted. IN C FB REF SW A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Reference Voltage Measured at Feedback Pin 1.230 1.245 1.260 V REF V = 0.8V 1.225 1.245 1.265 V C I Feedback Input Current V = V 250 550 nA FB FB REF 900 nA Reference Voltage Line Regulation 2.7V V 25V, V = 0.8V 0.01 0.03 %/V IN C V Negative Feedback Reference Voltage Measured at Negative Feedback Pin 2.525 2.48 2.435 V NFR Feedback Pin Open, V = 0.8V 2.560 2.48 2.400 V C I Negative Feedback Input Current V = V 45 30 15 A NFB NFB NFR Negative Feedback Reference Voltage 2.7V V 25V, V = 0.8V 0.01 0.05 %/V IN C Line Regulation g Error Amplifier Transconductance I = 25A 1100 1500 1900 mho m C 700 2300 mho Error Amplifier Source Current V = V 150mV, V = 1.5V 120 200 350 A FB REF C Error Amplifier Sink Current V = V + 150mV, V = 1.5V 1400 2400 A FB REF C sn1370 1370fs 2 U WU U W W W