ROHM Brings Hybrid Control to PFC and Flyback Supplies

Power supply design is often about trade-offs. Analog controllers are simple and efficient, but once engineers need advanced features like calibration or logging, they quickly run into limits. Digital controllers can provide those functions, yet the cost and power overhead are often too high for small and mid-range systems. ROHM’s LogiCoA™ platform was developed to bridge this gap, and its latest reference design shows how hybrid control can be applied to two of the most common converter types.

A Reference for Real-World Applications

The REF67004 evaluation board combines a Critical Conduction Mode power factor correction (PFC) stage with a Quasi-Resonant Flyback converter. Together, they provide a regulated 24V DC output from standard AC mains, a setup widely used in industrial robots, semiconductor tools, and compact consumer devices. What makes the design stand out is not the topologies themselves, but how they are controlled.

ROHM pairs its MOSFETs and driver ICs in the analog stage with a dedicated LogiCoA microcontroller. The result is a circuit that switches efficiently while also gaining digital functions such as calibration, protection, and logging. For engineers, it offers a middle ground: the low loss and simplicity of analog control with the configurability usually reserved for digital power.

Features That Reduce Design Burden

One challenge in any supply is dealing with part tolerances. The REF67004 addresses this by letting the MCU calibrate voltage control and current protection, reducing the need for oversized inductors or conservative margins. Smaller components free up PCB space and bring system costs down.

The design also supports operational logging. Data such as voltage, current, temperature, and pre-shutdown status can be stored in non-volatile memory, giving engineers visibility into how a supply behaves over time. This can shorten debug cycles and make field failures easier to trace. Access is straightforward, using a UART link and sample software supported by ROHM’s own RMOS operating system.

Evaluation and Outlook

Engineers can explore the hybrid approach through the LogiCoA003-EVK-001 board, which includes full documentation, schematics, and sample code.

With LogiCoA, ROHM is making the case for hybrid power supplies in the 50W to 1kW range. The REF67004 is more than a demo board, it’s an example of how mixing analog efficiency with digital control can ease design challenges while adding useful diagnostic features. As demand for compact, reliable supplies continues to grow, this approach could give engineers a valuable new tool.

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