Synchronous Boost Controller with up to 98% Efficiency Eliminates Heat Sink

Nov 10, 2010 1:41 PM

Linear Technology Corp. announces the LTC3786, a synchronous step-up DC/DC controller that replaces the boost diode with a high efficiency N-channel MOSFET. This eliminates the heat sink normally required in medium to high power boost converters. In applications where the input voltage may exceed the regulated output voltage, the LTC3786 is able to keep the synchronous MOSFET on continuously so that the output voltage follows the input voltage with minimal power loss. The LTC3786's low 55µA quiescent current extends the run time in battery-powered applications when in standby mode. This controller can produce a 24V at 5A output from a 12V input with up to 98% efficiency, making it ideal for automotive, industrial, and medical applications where a step-up DC/DC converter must have low heat dissipation in a small solution size.

The LTC3786 operates from an input voltage ranging from 4.5V to 38V during start-up, maintaining operation down to 2.5V after start-up and can regulate an output voltage as high as 60V. The powerful 1.2 Ohm onboard N-channel MOSFET gate drivers are capable of slewing large MOSFET gates quickly, minimizing transition losses and allowing for up to a 10A output current.

The LTC3786 has adjustable cycle-by-cycle current limit protection and uses either a sense resistor or monitors the voltage drop across the inductor (DCR) for current sensing. The LTC3786 has a phase-lockable switching frequency range of 75kHz to 850kHz and a fixed frequency operating range from 50kHz to 900kHz. Furthermore, the LTC3786 has adjustable soft-start and maintains ±1% reference voltage accuracy over an operating temperature range of -40°C to 125°C.

The LTC3786 is available in a thermally enhanced MSOP-16 package and a 3mm x 3mm QFN. The 1,000-piece price starts at $2.80 each and is available from stock.

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