LT3976 40V, 5A, 2MHz Step-Down Switching Regulator with 3.3A Quiescent Current Fea T Descrip T n Ultralow Quiescent Current: The LT 3976 is an adjustable frequency monolithic buck 3.3A I at 12V to 3.3V switching regulator that accepts a wide input voltage range Q IN OUT n Low Ripple Burst Mode Operation up to 40V. Low quiescent current design consumes only Output Ripple < 15mV 3.3A of supply current while regulating with no load. Low P-P n Wide Input Range: Operation from 4.3V to 40V ripple Burst Mode operation maintains high efficiency at n 5A Maximum Output Current low output currents while keeping the output ripple below n Excellent Start-Up and Dropout Performance 15mV in a typical application. The LT3976 can supply up n Adjustable Switching Frequency: 200kHz to 2MHz to 5A of load current and has current limit foldback to n Synchronizable Between 250kHz to 2MHz limit power dissipation during short-circuit. A low dropout n Accurate Programmable Undervoltage Lockout voltage of 500mV is maintained when the input voltage n Low Shutdown Current: I = 700nA drops below the programmed output voltage, such as Q n Power Good Flag during automotive cold crank. n Soft-Start Capability An internally compensated current mode topology is used n Thermal Shutdown Protection for fast transient response and good loop stability. A high n Current Limit Foldback with Soft-Start Override efficiency 75m switch is included on the die along with a n Saturating Switch Design: 75m On-Resistance boost Schottky diode. An accurate 1.02V threshold enable n Small, Thermally Enhanced 16-Lead MSOP and pin can be driven directly from a microcontroller or used 24-Lead 3mm 5mm QFN Packages as a programmable undervoltage lockout. A capacitor on the SS pin provides a controlled inrush current (soft-start). a T A power good flag signals when V reaches 91.6% of OUT n Automotive Battery Regulation the programmed output voltage. The LT3976 is available n Portable Products in small 16-lead MSOP and 24-lead 3mm 5mm QFN n Industrial Supplies packages with exposed pad for low thermal resistance. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical a T No-Load Supply Current 3.3V Step-Down Converter 8 IN REGULATION V IN V = 3.3V 7 OUT 4.3V TO 40V V IN 6 OFF ON EN BOOST 0.47F 3.3H 5 PG SW 4 10F PDS540 2 LT3976 470pF 3 SS OUT 2 1M V OUT 3.3V RT FB 1 10pF 5A SYNC GND 10nF 0 47F 130k 576k 0 5 10 15 20 25 30 35 40 1210 INPUT VOLTAGE (V) 2 3976 TA01a f = 400kHz 3976 G05 3976f 1 For more information www.linear.com/3976 INPUT CURRENT (A) ion pplica ions pplica ion uresLT3976 a T e Maxi Mu M r a T (Note 1) V , EN Voltage (Note 3) ...........................................40V Operating Junction Temperature Range (Note 2) IN BOOST Pin Voltage ...................................................55V LT3976E ............................................. 40C to 125C BOOST Pin Above SW Pin .........................................30V LT3976I ............................................. 40C to 125C FB, RT, SYNC, SS Voltage ...........................................6V LT3976H ............................................ 40C to 150C PG Voltage ................................................................30V Storage Temperature Range .................. 65C to 150C OUT Voltage ..............................................................16V Lead Temperature (Soldering, 10 sec) ...................300C p c F T TOP VIEW 24 23 22 21 1 SS 20 SYNC TOP VIEW OUT 2 19 PG FB 1 16 SYNC SS 2 15 PG NC 3 18 RT OUT 3 14 RT BST 4 17 NC BOOST 4 17 13 EN 25 SW 5 GND 12 V IN NC 5 EN 16 GND SW 6 11 V IN SW 7 10 V 6 IN SW 15 VIN NC 8 9 NC SW 7 14 VIN MSE PACKAGE SW 8 VIN 13 16-LEAD PLASTIC MSOP = 40C/W 9 10 11 12 JA EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB UDD PACKAGE 24-LEAD (3mm 5mm) PLASTIC QFN = 46C/W JA EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB o r D i n F Ma T LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3976EMSE PBF LT3976EMSE TRPBF 3976 16-Lead Plastic MSOP 40C to 125C LT3976IMSE PBF LT3976IMSE TRPBF 3976 16-Lead Plastic MSOP 40C to 125C LT3976HMSE PBF LT3976HMSE TRPBF 3976 16-Lead Plastic MSOP 40C to 150C LT3976EUDD PBF LT3976EUDD TRPBF LGHV 24-Lead (3mm 5mm) Plastic QFN 40C to 125C LT3976IUDD PBF LT3976IUDD TRPBF LGHV 24-Lead (3mm 5mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: