Single Inductor High Efficiency Synchronous Buck-Boost DC/DC Controller

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

The LTC3789 employs a proprietary current-mode control architecture for constant frequency operation in buck or boost mode and has powerful onboard quad N-channel MOSFET gate drivers. The LTC3789 also provides an accurate, constant-current regulation loop for either input or output current, over a wide input voltage range. The input current limit function prevents overloading of the input source, and the output current limit provides an easy solution for regulated output current applications such as battery 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. The user can select continuous or pulse skip mode to maximize light load efficiency. Furthermore, the LTC3789 has adjustable soft-start, a power good output and maintains ±1.5% reference voltage accuracy over an operating junction temperature range of -40°C to 125°C.