LTC1649 3.3V Input High Power Step-Down Switching Regulator Controller DESCRIPTIO FEATURES The LTC 1649 is a high power, high efficiency switching n High Power 3.3V to 1.xV-2.xV Switching Regulator regulator controller optimized for use with very low supply Controller: Up to 20A Output voltages. It operates from 2.7V to 5V input, and provides n All N-Channel External MOSFETs a regulated output voltage from 1.26V to 2.5V at up to 20A n Provides 5V MOSFET Gate Drive with 3.3V Input load current. A typical 3.3V to 2.5V application features n Excellent Output Regulation: 1% Over Line, Load efficiency above 90% from 1A to 10A load. The LTC1649 and Temperature Variations uses a pair of standard 5V logic-level N-channel external n Constant Frequency Operation Minimizes MOSFETs, eliminating the need for expensive P-channel Inductor Size or super-low-threshold devices. n High Efficiency: Over 90% Possible n No Low-Value Sense Resistor Needed The LTC1649 shares its internal switching architecture n Available in 16-Lead SO Package with the LTC1430, and features the same 1% line, load and temperature regulation characteristics. Current limit U is user-adjustable without requiring an external low-value APPLICATIO S sense resistor. The LTC1649 uses a 200kHz switching n 3.3V Input Power Supply for Low Voltage frequency and voltage mode control, minimizing external Microprocessors and Logic component count and size. Shutdown mode drops the n Low Input Voltage Power Supplies quiescent current to below 10m A. n High Power, Low Voltage Regulators The LTC1649 is available in the 16-pin narrow SO package. n Local Regulation for Multiple Voltage Distributed , LTC and LT are registered trademarks of Linear Technology Corporation. Power Systems TYPICAL APPLICATIO 3.3V to 2.5V, 15A Converter LTC1649 Efficiency V IN 100 3.3V + R IMAX Q1, Q2 C IN 50k IRF7801 3300F 1F MBR0530 90 TWO IN L * PARALLEL EXT 1.2H 80 P G1 V OUT VCC1 2.5V 22 1k 15A P I VCC2 FB R1 70 12.4k Q3 V G2 CC IRF7801 LTC1649 60 I FB MAX + C SHDN V OUT SHDN IN 4400F 50 + + C 10F COMP 1F SS C 40 R C R2 7.5k GND CP 0.1 1 10 OUT 12.7k C C LOAD CURRENT (A) 0.01F 1649 TA02 + C1 0.1F 10F 0.33F MBR0530 220pF 1649 TA01 IRF7801 = INTERNATIONAL RECTIFIER MBR0530 = MOTOROLA *12TS-1R2HL = PANASONIC 1 EFFICIENCY (%) U ULTC1649 UUW ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) TOP VIEW ORDER PART Supply Voltage NUMBER G1 1 16 G2 V ........................................................................................... 6V IN P 2 15 P VCC1 VCC2 V ........................................................................................... 9V LTC1649CS CC GND 3 14 V CC P ................................................................................ 13V LTC1649IS VCC1, 2 FB 4 13 I FB Input Voltage SHDN 5 12 I MAX I ....................................................................... 0.3V to 18V FB SS 6 11 COMP + C , C ................................................ 0.3V to (V + 0.3V) IN V 7 10 CP IN OUT All Other Inputs ....................... 0.3V to (V + 0.3V) + C 8 9 CC C Operating Temperature Range S PACKAGE LTC1649C ............................................... 0 C to 70 C 16-LEAD PLASTIC SO LTC1649I............................................ 40 C to 85 C T = 150 C, q = 110 C/ W JMAX JA Storage Temperature Range ................. 65 C to 150 C Consult factory for parts specified with wider operating temperature ranges. Lead Temperature (Soldering, 10 sec).................. 300 C The l denotes the specifications which apply over the full operating ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T = 25 C. V = 3.3V (Note 2) A IN LTC1649CS LTC1649IS SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS V Minimum Supply Voltage Figure 1 (Note 3) l 2.7 2.7 V IN V Feedback Voltage Figure 1 l 1.25 1.265 1.28 1.23 1.265 1.29 V FB V Charge Pump Output Voltage Figure 1 l 4.8 5 5.2 4.75 5 5.25 V CPOUT I Supply Current (V)V = V , I = 0 l 35 3 5 mA IN IN SHDN CC LOAD V = 0V 10 25 10 25 m A SHDN I Supply Current (P)P = 5V, V = V (Note 4) 1.5 1.5 mA PVCC1, 2 VCC1, 2 VCC SHDN CC V = 0V 0.1 0.1 m A SHDN f Internal Charge Pump Frequency I = 20mA (Note 5) 700 700 kHz CP CPOUT f Internal PWM Oscillator Frequency l 140 200 260 130 200 325 kHz OSC V SHDN Input High Voltage l 2.4 2.4 V IH V SHDN Input Low Voltage l 0.8 0.8 V IL I SHDN Input Current l 0.01 1 0.01 1 m A IN gm Error Amplifier Transconductance 650 650 m Mho V gm I Amplifier Transconductance (Note 6) 1300 1300 m Mho I LIM I I Sink Current V = V l 8 12 16 8 12 17 m A IMAX MAX IMAX CC I Soft Start Source Current V = 0V l 8 12 16 8 12 17 m A SS SS t , t Driver Rise/Fall Time P = P = 5V (Note 7) 80 250 80 250 ns r f VCC1 VCC2 t Driver Non-Overlap Time P = P = 5V 25 130 250 25 130 250 ns NOV VCC1 VCC2 DC Maximum Duty Cycle V = V 90.5 93 90.5 93 % MAX COMP CC 2 W U WW