POWER LOSS (mW) LT3481 36V, 2A, 2.8MHz Step-Down Switching Regulator with 50A Quiescent Current FEATURES DESCRIPTION Wide Input Range: 3.6V to 34V Operating, The LT 3481 is an adjustable frequency (300kHz to 2.8MHz) 36V Maximum monolithic buck switching regulator that accepts input 2A Maximum Output Current voltages up to 34V (36V maximum). A high ef ciency Low Ripple Burst Mode Operation 0.18 switch is included on the die along with a boost 50A I at 12V to 3.3V Schottky diode and the necessary oscillator, control, and Q IN OUT Output Ripple < 15mV logic circuitry. Current mode topology is used for fast Adjustable Switching Frequency: 300kHz to 2.8MHz transient response and good loop stability. Low ripple Low Shutdown Current: I < 1A Burst Mode operation maintains high ef ciency at low Q Integrated Boost Diode output currents while keeping output ripple below 15mV Power Good Flag in a typical application. In addition, the LT3481 can fur- Saturating Switch Design: 0.18 On-Resistance ther enhance low output current ef ciency by drawing 1.265V Feedback Reference Voltage bias current from the output when V is above 3V. OUT Output Voltage: 1.265V to 20V Shutdown reduces input supply current to less than 1A Soft-Start Capability while a resistor and capacitor on the RUN/SS pin provide a Synchronizable Between 275kHz to 475kHz controlled output voltage ramp (soft-start). A power good Small 10-Pin Thermally Enhanced MSOP and ag signals when V reaches 90% of the programmed OUT (3mm x 3mm) DFN Packages output voltage. The LT3481 is available in 10-Pin MSOP and 3mm x 3mm DFN packages with exposed pads for low thermal resistance. APPLICATIONS L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their Automotive Battery Regulation respective owners. Power for Portable Products Distributed Supply Regulation Industrial Supplies Wall Transformer Regulation TYPICAL APPLICATION 3.3V Step-Down Converter Ef ciency V V 90 10000.0 IN OUT 4.5V TO 3.3V 34V 2A V BD IN 80 1000.0 OFF ON RUN/SS BOOST 70 100.0 0.47F 4.7H 16.2k V SW C LT3481 60 10.0 4.7F RT 330pF 50 1.0 PG BIAS V = 12V IN 324k V = 3.3V OUT 40 0.1 60.4k FB L = 4.7 GND F = 800 kHz 22F 200k 30 0.01 0.0001 0.001 0.01 0.1 1 10 LOAD CURRENT (A) 3481 TA01 3481 TA01b 3481fc 1 EFFICIENCY (%)LT3481 (Note 1) ABSOLUTE MAXIMUM RATINGS V , RUN/SS Voltage .................................................36V Operating Temperature Range (Note 2) IN BOOST Pin Voltage ...................................................56V LT3481E ............................................... 40C to 85C BOOST Pin Above SW Pin .........................................30V LT3481I.............................................. 40C to 125C FB, RT, V Voltage .......................................................5V LT3481H ............................................ 40C to 150C C BIAS, PG, BD Voltage ................................................30V Storage Temperature Range ................... 65C to 150C Maximum Junction Temperature........................... 125C Lead Temperature (Soldering, 10 sec) LT3481E, LT3481I .............................................125C MSE Only .......................................................... 300C LT3481H ........................................................... 150C PIN CONFIGURATION TOP VIEW TOP VIEW BD 1 10 RT BD 1 10 RT BOOST 2 9 V C BOOST 2 9 V C 11 SW 3 11 8 FB SW 3 8 FB V 4 7 BIAS IN V 4 7 BIAS IN RUN/SS 5 6 PG RUN/SS 5 6 PG MSE PACKAGE 10-LEAD PLASTIC MSOP DD PACKAGE 10-LEAD (3mm s 3mm) PLASTIC DFN EXPOSED PAD (PIN 11) IS GND MUST BE CONNECTED TO GND EXPOSED PAD (PIN 11) IS GND = 40C/W JA MUST BE CONNECTED TO GND = 43C/W JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3481EDD PBF LT3481EDD TRPBF LBVS 10-Lead (3mm 3mm) Plastic DFN 40C to 85C LT3481IDD PBF LT3481IDD TRPBF LBVV 10-Lead (3mm 3mm) Plastic DFN 40C to 125C LT3481HDD PBF LT3481HDD TRPBF LBVS 10-Lead (3mm 3mm) Plastic DFN 40C to 150C LT3481EMSE PBF LT3481EMSE TRPBF LTBVT 10-Lead Plastic MSOP 40C to 85C LT3481IMSE PBF LT3481IMSE TRPBF LTBVW 10-Lead Plastic MSOP 40C to 125C LT3481HMSE PBF LT3481HMSE TRPBF LTBVT 10-Lead Plastic MSOP 40C to 150C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3481EDD LT3481EDD TR LBVS 10-Lead (3mm 3mm) Plastic DFN 40C to 85C LT3481IDD LT3481IDD TR LBVV 40C to 125C 10-Lead (3mm 3mm) Plastic DFN LT3481HDD LT3481HDD TR LBVS 40C to 150C 10-Lead (3mm 3mm) Plastic DFN LT3481EMSE LT3481EMSE TR LTBVT 10-Lead Plastic MSOP 40C to 85C LT3481IMSE LT3481IMSE TR LTBVW 10-Lead Plastic MSOP 40C to 125C LT3481HMSE LT3481HMSE TR LTBVT 10-Lead Plastic MSOP 40C to 150C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. For more information on lead free part marking, go to: