ADI 72V Hybrid Step-Down DC/DC Controller Reduces Solution Size by 50% Compared to Traditional Architectures


Analog Devices Inc. announced the Power by Linear LTC7821, a hybrid step-down synchronous controller that merges a switched capacitor circuit with a synchronous step-down controller, enabling up to a 50% reduction in DC/DC converter solution size compared to traditional step-down solutions, according to the company. This improvement is enabled by a 3x higher switching frequency without compromising efficiency. Alternatively, when operating at the same frequency, a LTC7821-based solution can provide up to 3% higher efficiency. Other benefits include low electromagnetic interference (EMI) and reduced metal-oxide semiconductor field-effect transistor (MOSFET) stress due to a soft-switched front end, which is intended for next-generation non-isolated intermediate bus applications in power distribution, datacom, and telecom as well as emerging 48-V automotive systems.

The LTC7821 operates over a 10-V to 72-V (80-V abs max) input voltage range and can produce an output voltage from 0.9 V to 33.5 V with currents in multiple 10s of amps, depending on the choice of external components. In a typical 48-V to 12-V/20-A application, an efficiency of 97% is attainable with the LTC7821 switching at 500 kHz. The same efficiency can only be achieved in a traditional synchronous step-down converter by switching at one-third the operating frequency, resulting in the use of much larger magnetics and output filter components. External MOSFETs switch at a fixed frequency programmable from 200 kHz to 1.5 MHz. The LTC7821’s powerful 1 Ohm N-channel MOSFET gate drivers maximize efficiency and can drive multiple MOSFETs in parallel for higher power applications.

The LTC7821 implements many proprietary protection features for robust performance in a wide range of applications.

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