Power Electronics

Dual Output, High Power 60V Synchronous Boost Controller Eliminates Heat Sink with 97% Efficiency

Linear Technology Corporation announces the LTC3788/-1, a dual output, high power synchronous step-up switching 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. The LTC3788/-1 can produce a 24V at 5A output with up to 97% efficiency, making it ideal for high power automotive audio amplifiers, industrial and medical applications where a step-up DC/DC converter must deliver high power with low heat dissipation in a small solution size.

The LTC3788/-1 operates from an input voltage ranging from 4.5V to 38V during start-up, maintains operation down to 2.5V after start-up and can regulate an output voltage as high as 60V. The powerful 1.5Ohm onboard N-channel MOSFET gate drivers are capable of slewing large MOSFET gates quickly, minimizing transition losses and allowing for up to a 10A per channel output current. In addition, the LTC3788/-1 draws only 125µA when one output is active and only 200µA when both outputs are enabled.

The constant frequency current mode architecture allows for paralleled outputs. The LTC3788 includes a clock output, phase modulation (for multiphase applications), two separate power good outputs and an adjustable current limit. The LTC3788/-1 has a phase-lockable frequency from 75kHz to 850kHz or a selectable fixed frequency from 50kHz to 900kHz. It 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. In applications where the input voltage may sometimes exceed the regulated output voltage, the LTC3788/-1 is able to keep the synchronous MOSFET on continuously so that the output voltage follows the input voltage with minimal power loss. Furthermore, the LTC3788/-1 has adjustable soft-start and maintains ±1% reference voltage accuracy over an operating temperature range of -40ºC to 125ºC.

The LTC3788-1 is available in an SSOP-28 package and the LTC3788 is housed in a 32-lead 5mm x 5mm QFN. The 1,000-piece price starts at $4.12 each. Both versions are available from stock.

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