Single Inductor High Efficiency Synchronous

LinearTechnology Corp.'s LTC3789 is a high efficiency,up to 98 percent, synchronous buck-boost dc/dc controller that operates frominput voltages above, below or equal to the regulated output voltage. Highpower circuits that step-up and-down typically rely on transformers or twodc/dc converters, one for step-up (boost) and the other for step-down (buck)conversion. The LTC3789 operates using a single inductor with 4-switchsynchronous rectification and can deliver output power up to 150W with a singledevice. Even higher output power can be achieved when multiple circuits areparalleled.

The LTC3789 operates with a selectable fixed frequency between 200 and 600 kHz,and can be synchronized to an external clock over the same range with itsintegrated phase-locked loop (PLL). Its wide 4 to 38V input range, 0.8 to 38Voutput range and seamless transitions between operating modes make it ideal fora wide range of industrial controls, automotive, solar and high powerbattery-supplied systems.

The LTC3789 employs a proprietary current-modecontrol architecture for constant frequency operation in buck or boost mode andhas powerful onboard quad N-channel MOSFET gate drivers. The LTC3789 alsoprovides an accurate, constant-current regulation loop for either input oroutput current, over a wide input voltage range. The input current limitfunction prevents overloading of the input source, and the output current limitprovides an easy solution for regulated output current applications such asbattery charger or LED drivers. Fault protection is provided for overvoltage,overcurrent and short circuit conditions in all operating modes. In addition,the LTC3789 disconnects the input voltage from the output when in shutdown. Theuser can select continuous or pulse skip mode to maximize light loadefficiency. The LTC3789 has adjustable soft-start, a power good output andmaintains A plus or minus 1.5 percent reference voltage accuracy over an operating junctiontemperature range of -40 to 125C.

The LTC3789 is available in 28-pin 4 x 5mm QFN and 28-lead SSOP packages.Pricing starts at $4.65 each in 1,000-piece quantities.

Single Inductor High Efficiency Synchronous