Power Electronics

Linear Technology adds single-inductor, high-power buck-boost dc/dc controller

The LTC3780 from Linear Technology Corporation is a high-performance buck-boost switching regulator controller, suited for automotive applications, that operates from input voltages above, below or equal to the output voltage. It offers three operating modes--constant frequency, burst mode, and discontinuous current.

Until now, according to the company, high-power buck-boost circuits have relied on transformers or two dc/dc converters--one for step-up (boost) and the other for step-down (buck) conversion. With a single inductor, the LTC3780 can deliver output power as high as 75 W, and 4-switch synchronous rectification delivers efficiencies up to 97%. The constant frequency current mode architecture allows a phase-lockable frequency of up to 400 kHz. The controller’s input range is 4 V to 30 V (36 V max). Its output range is 0.8 V to 30 V.

The device uses a proprietary current control architecture for constant frequency operation in buck or boost mode. Fault protection is provided for overvoltage, overcurrent and short circuit conditions in all operating modes. A power good output open-drain pin signals whether the output voltage is in or out of regulation.

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