LTC3785 10V, High Efficiency, Synchronous, No R SENSE Buck-Boost Controller Fae Tseru Dpircse Tnoi n The LTC 3785 is a high power synchronous buck-boost Single Inductor Architecture Allows V Above, IN controller that drives all N-channel power MOSFETs from Below or Equal to V OUT n input voltages above, below and equal to the output volt- 2.7V to 10V Input and Output Range n age. With an input range of 2.7V to 10V, the LTC3785 is Up to 96% Efficiency n well suited for a wide variety of single or dual cell Li-Ion Up to 10A of Output Current n or multicell alkaline/NiMH applications. All N-channel MOSFETs, No R SENSE n True Output Disconnect During Shutdown The operating frequency can be programmed from n Programmable Current Limit and Soft-Start 100kHz to 1MHz. The soft-start time and current limit are n Optional Short-Circuit Shutdown Timer also programmable. The soft-start capacitor doubles as n Output Overvoltage and Undervoltage Protection the fault timer which can program the IC to latch off or n Programmable Frequency: 100kHz to 1MHz recycle after a determined off time. Burst Mode opera- n Selectable Burst Mode Operation tion is user controlled and can be enabled by driving the n Available in 24-Lead (4mm 4mm) Exposed Pad MODE pin high. QFN Package Protection features include foldback current limit, short- circuit and overvoltage protection. a acilpp Tsnoi L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. No R is a trademark of Linear Technology Corporation. SENSE n Palmtop Computers All other trademarks are the property of their respective owners. n Handheld Instruments n Wireless Modems n Cellular Telephones T lacipy a acilpp Tnoi V IN 2.7V V OUT Efficiency vs Input Voltage 4.7F TO 10V V IN V CC 100 V = 3.3V OUT 205k I SVIN F = 500kHz OSC 22F V TG1 SENSE 1.3k 205k 121k 95 V BST1 I = 2A 270pF LOAD 0.22F FB SW1 I = 1A I LOAD SSW1 121k 12k V DRV 4.7H 90 BG1 1nF LTC3785 V C V 59k OUT RT I 3.3V SVOUT 5A MODE TG2 85 2.5 4 5.5 7 8.5 10 V (V) IN V 3785 TA01b BST2 0.22F RUN/SS SW2 I I 100F LSET SSW2 42.2k CCM BG2 1nF GND 3785 TA01a 3785fc EFFICIENCY (%)LTC3785 a ulosb T e Mixa Mu M r a Tsgni p ni c no Farugi Tnoi (Note 1) TOP VIEW Input Supply Voltage (V ) ......................... 0.3V to 11V IN I , I .............................................. 0.3V to 11V SVOUT SVIN 24 23 22 21 20 19 SW1, SW2, I , I Voltage: SSW1 SSW2 RUN/SS 1 18 I SSW1 DC ............................................................. 1V to 11V V 2 17 BG1 C Pulsed, <1s ............................................. 2V to 12V FB 3 16 V DRV 25 RUN/SS, MODE, CCM, V , V Voltages .. 0.3V to 6V DRV CC GND V 4 15 BG2 SENSE V Voltage ............................................. 0.3V to 16V BST1 I I 5 14 LSET SSW2 With Respect to SW1 ............................... 0.3V to 6V CCM 6 13 SW2 V Voltage ............................................. 0.3V to 16V BST2 7 8 9 10 11 12 With Respect to SW2 ............................... 0.3V to 6V Peak Driver Output Current < 10s UF PACKAGE (TG1, TG2, BG1, BG2) .................................................3A 24-LEAD (4mm 4mm) PLASTIC QFNs V Average Output Current .................................100mA T = 125C, = 40C/W 1 LAYER BOARD, = 30C/W 4 LAYER BOARD CC JMAX JA JA EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB Operating Junction Temperature Range (Note 2) ..................................................40C to 125C Junction Temperature ........................................... 125C Storage Temperature Range ...................65C to 150C o r D re i n Fro Ma Tnoi LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3785EUF PBF LTC3785EUF TRPBF 3785 24-Lead (4mm 4mm) Plastic QFN 40C to 85C LTC3785IUF PBF LTC3785IUF TRPBF 3785 24-Lead (4mm 4mm) Plastic QFN 40C to 125C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3785EUF LTC3785EUF TR 3785 40C to 85C 24-Lead (4mm 4mm) Plastic QFN LTC3785IUF LTC3785IUF TR 3785 24-Lead (4mm 4mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts speciefi d with wider operating temperature ranges. *The temperature grade is identiefi d by a label on the shipping container. For more information on lead free part marking, go to:
