LT1619 Low Voltage Current Mode PWM Controller FEATURES DESCRIPTIO n Wide V Range: 1.9V to 18V The LT 1619 is a fixed frequency PWM controller for IN n 300kHz Fixed Frequency Current Mode Control implementing current mode DC/DC converters with mini- n mum external parts. The LT1619 operates with input 1A Rail-to-Rail N-Channel MOSFET Driver n Low 53mV Current Limit Threshold Voltage voltages ranging from 1.9V to 18V and is suitable for a Improves Efficiency variety of battery-powered and distributed DC/DC con- n verters. The internal rail-to-rail N-channel MOSFET driver Implements Boost, SEPIC and Flyback Converters Requiring Low Side Power Transistors operates either from the input in the nonbootstrapped n Internal Current Sense Amplifier mode or from the output in bootstrapped operation. The driver is designed to drive a low side power transistor in with Leading Edge Blanking n Up to 500kHz External Synchronization boost, SEPIC, flyback and other topologies. n Burst Mode Operation for High Efficiency Converter efficiency is improved at heavy loads with a at Light Load 53mV current sense voltage and at light load with Burst n 140m A Quiescent Current Mode operation. The operating frequency is internally set n 15m A Shutdown Current at 300kHz. The oscillator can also be synchronized exter- n 8-Lead MSOP and SO Packages nally up to 500kHz. No load quiescent current is 140m A and shutdown current is 15m A. U APPLICATIO S The LT1619 is available in 8-lead MSOP and SO packages. , LTC and LT are registered trademarks of Linear Technology Corporation. n 3.3V to 5V DC/DC Converters Burst Mode is a registered trademark of Linear Technology Corporation. n Distributed Power Supplies n Isolated Power Supplies TYPICAL APPLICATIO Efficiency V IN 3.3V 95 90 1 8 L1 37.4k S/S V IN + 5.6H C1 0.1F 5A 22F 12.4k 2 7 85 FB DRV V OUT 5V LT1619 0.1F 3 6 2.2A M1 D1 V GATE C 80 Si9804 + 75k C OUT 4 5 440F 220pF GND SENSE 75 15nF R SENSE 0.01 1619 F01 70 C1: PANASONIC EEFCDOK220R 1 10 100 1000 C : KEMET T495X227K010AS ( 2) OUT LOAD CURRENT (mA) D1: MBRD835L 1619 F01a L1: COILCRAFT DO5022P-562 Figure 1. High Efficiency 3.3V to 5V DC/DC Converter 1619fa 1 EFFICIENCY (%) U ULT1619 ABSOLUTE AXI U RATI GS (Note 1) Input Voltage (V ) ................................... 0.3V to 20V Current Sense Voltage (SENSE) ................. 0.5V to V IN IN Gate Drive Supply Voltage (DRV) ............. 0.3V to 20V Operating Temperature Range (Note 2) .. 40 C to 85 C Shutdown/Synch Voltage (S/S) ................ 0.3V to 20V Junction Temperature (Note 3)............................. 125 C Feedback Voltage (FB) .............................................. V Storage Temperature Range ................. 65 C to 150 C IN Compensation Voltage (V ) ...................................... 3V Lead Temperature (Soldering, 10 sec).................. 300 C C Gate Drive Output Current (GATE) ........................ 1.5A UUW PACKAGE/ORDER I FOR ATIO ORDER PART ORDER PART NUMBER NUMBER TOP VIEW TOP VIEW S/S 1 8 V IN S/S 1 8 V LT1619EMS8 LT1619ES8 IN FB 2 7 DRV FB 2 7 DRV V 3 6 GATE C V GATE 3 6 C GND 4 5 SENSE GND SENSE 4 5 MS8 PACKAGE MS8 PART MARKING S8 PART MARKING 8-LEAD PLASTIC MSOP S8 PACKAGE T = 125 C, q = 200 C/ W 8-LEAD PLASTIC SO JMAX JA 1619 LTHC T = 125 C, q = 120 C/ W JMAX JA Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are at T = 25 C. A V = V = 2.5V, V = V , COMP open, V = 0V unless otherwise noted. IN DRV S/S IN SENSE PARAMETER CONDITIONS MIN TYP MAX UNITS Reference Voltage Measured at the FB Pin l 1.22 1.24 1.26 V Reference Line Regulation 1.9V V 18V 0.004 0.05 %/V IN FB Input Bias Current V = V 10 25 nA FB REF 1 Error Amplifier Transconductance 80 170 260 Error Amplifier Output Source Current V = 1V, V = 1V 4 8.7 14 m A FB COMP Error Amplifier Output Sink Current V = 1.5V, V = 1V 4 8.7 14 m A FB COMP Error Amplifier Clamp Voltage V = 1V 1.6 2.2 V FB Undervoltage Lockout Threshold 1.65 1.85 V Input Voltage Range l 1.9 18 V Switching Frequency 1.9V V 18V l 220 300 360 kHz IN Synchronization Frequency Range 370 500 kHz Maximum Duty Cycle l 88 92 % Current Limit Threshold l 40 53 66 mV Burst Mode Operation Current Limit 10 mV 1619fa 2 mW U WWW