Isolated forward converter chipset simplifies design, enhances system reliability

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By eeNews Europe

After start-up, the LTC3765 receives timing signals and bias power from the secondary-side LTC3766 controller through a pulse transformer. Secondary-side control puts the brains near the load, ensuring reliable control of the output voltage and current while providing the fastest transient response and eliminating the need for an optocoupler.

In traditional active clamp forward converters, a large change in output load or input voltage can cause the power transformer to saturate, resulting in converter failure. Direct Flux Limit prevents transformer saturation under all conditions, increasing overall converter reliability while maintaining a superior transient response when compared to alternative solutions. This type of forward converter design is well suited for 12 V, 24 V and 48 V nominal input voltages that are commonly found in telecom, datacom and industrial applications.

The LTC3765/LTC3766 contains control circuitry to implement an active clamp transformer reset technique enabling higher efficiencies (up to 96%) and greater power densities when compared to conventional catch winding or resonant reset techniques. High current gate drivers for the main switch, the active clamp switch and the synchronous switches include adjustable delays to achieve maximum efficiency. Additional features include a fast and accurate average current limit, fixed-frequency adjustable operation from 75 kHz to 500 kHz, clean start-up into pre-biased loads, multiphase operation for high power designs, overtemperature protection and true remote output voltage sense.

Availability and Pricing

The LTC3765 is available in a thermally enhanced MSOP-16 package and the 1,000-piece price starts at $1.55. The LTC3766 is available in a 4 mm x 5 mm QFN-28 and SSOP-28 packages and the 1,000-piece pricing starts at $2.60.

More information about the LTC3765 and LTC3766 synchronous forward converter chipset visit: and


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