The Power by Linear LTC7821’s structure enables up to a 50% reduction in DC/DC converter size compared to traditional step-down solutions, claims Analog Devices. This is enabled by a 3X higher switching frequency without compromising efficiency, it adds. When operating at the same frequency, it can provide up to a 3% higher efficiency.

Low EMI and reduced MOSFET stress are due to a soft-switched front end, suitable for next-generation non-isolated intermediate bus applications in power distribution, datacomms and telecomms as well as emerging 48V automotive systems.

The controller operates over a 10 to 72V (80V max) input voltage range and can produce an output voltage from 0.9 to 33.5V with currents in multiple 10s of A, depending on the choice of external components. In a typical 48 to 12V/20A application, an efficiency of 97% is attainable with the DC/DC controller switching at 500kHz. The same efficiency can only be achieved in a traditional synchronous step-down converter by switching at one-third the operating frequency, and using much larger magnetics and output filter components, says the company. External MOSFETs switch at a fixed frequency programmable from 200kHz to 1.5MHz.  The 1Ω n-channel MOSFET gate drivers maximise efficiency and can drive multiple MOSFETs in parallel for higher power applications. The current mode control architecture allows multiple LTC7821s to be operated in a parallel, multi-phase configuration with current sharing to enable much higher power applications.

The in-rush current typically associated with switched capacitor circuits is eliminated by pre-balancing the capacitors during start-up. The controller also monitors system voltage, current and temperature for faults, and uses a sense resistor for overcurrent protection. It stops switching and pulls the /fault pin low when a fault occurs. An onboard timer can be set for restart/retry times. The EXTV_CC pin enables the step down DC/DC controller to be powered from the lower voltage output of the converter or other available source up to 40V, reducing power dissipation and improving efficiency. Additional features include ±1% output voltage accuracy over temperature, a clock output for multi-phase operation, a power good output signal, short-circuit protection, monotonic output voltage start-up, optional external reference, under-voltage lockout and internal charge balance circuitry.

The controller is available in a 5.0 x 5.0mm QFN-32 package. Extended and industrial temperature versions are available.