LTC3785-1 10V, High Effi ciency, Buck-Boost Controller with Power Good FEATURESDESCRIPTION n Single Inductor Architecture Allows VIN Above, The LTC®3785-1 is a high power synchronous buck-boost Below or Equal to VOUT controller that drives all N-channel power MOSFETs from n Power Good Output Indicator input voltages above, below and equal to the output volt- n 2.7V to 10V Input and Output Range age. With an input range of 2.7V to 10V, the LTC3785-1 is n Up to 96% Effi ciency well suited for a wide variety of single or dual cell Li-Ion n Up to 10A of Output Current or multicell alkaline/NiMH applications. n All N-channel MOSFETs, No RSENSE™ The operating frequency can be programmed from 100kHz n True Output Disconnect During Shutdown to 1MHz. The soft-start time and current limit are also n Programmable Current Limit and Soft-Start programmable. The soft-start capacitor doubles as the n Optional Short-Circuit Shutdown Timer fault timer which can program the IC to latch off or recycle n Output Overvoltage and Undervoltage Protection after a determined off time. Burst Mode operation is user n Programmable Frequency: 100kHz to 1MHz controlled and can be enabled by driving the mode pin n Selectable Burst Mode® Operation high. The LTC3785-1 includes a power good output that n Available in 24-Lead (4mm × 4mm) Exposed Pad indicates when the output voltage is within 7.5% of its QFN Package designed setpoint. Protection features include foldback current limit, APPLICATIONS short-circuit and overvoltage protection. n Palmtop Computers L n , LT, LTC ,LTM and Burst Mode are registered trademarks of Linear Technology Corporation. Handheld Instruments No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the n Wireless Modems property of their respective owners. n Cellular Telephones TYPICAL APPLICATION VIN 2.7V V Effi ciency vs Input Voltage OUT 4.7μF TO 10V VIN 100 VCC VOUT = 3.3V 215k F I OSC = 500kHz SVIN V TG1 22μF SENSE 1.3k 215k 127k A 95 V I BST1 270pF LOAD = 2A 0.22μF FB SW1 ILOAD = 1A ISSW1 127k 12k VDRV EFFICIENCY (%) 90 BG1 4.7μH 1nF LTC3785-1 V B C VOUT RT ISVOUT 3.3V 5A 85 49.9k 2.5 4 5.5 7 8.5 10 MODE TG2 VIN (V) D 37851 TA01b PGOOD VBST2 0.22μF RUN/SS SW2 I I LSET SSW2 100μF CCM BG2 2.2nF 42.2k GND C 37851 TA01a 37851fa 1
