ROHM releases a new compact PFC + flyback control reference design for power
ROHM’s new reference design (REF67004) is capable of controlling two commonly used power converter types in consumer and industrial power supply applications by using a single MCU: critical conduction mode PFC (Power Factor Correction) and quasi-resonant flyback. This is part of ROHM’s LogiCoA Power Supply Solution, that leverages analog-digital hybrid control technology. It combines an analog-controlled power stage circuit featuring ROHM’s superior silicon MOSFETs and gate driver ICs with a digitally managed power supply circuit built around the low-power LogiCoA MCU.
Analog-controlled power supplies are widely used in small- to medium-power industrial applications, such as industrial robots and semiconductor manufacturing equipment. However, growing demands for higher reliability and more precise control have made it increasingly difficult for analog-only configurations to meet market expectations. On the other hand, while fully digital power supplies offer fine control and greater flexibility, their adoption in the small to medium power range has been limited due to the high cost and power consumption of digital controllers.
To overcome these challenges, ROHM has developed the LogiCoA Power Supply Solution, a hybrid approach that integrates the advantages of both analog and digital control. Combined with ROHM’s high-performance, the low power LogiCoA MCUs enable easy control of various power topologies. As the first step, ROHM has released the REF66009 evaluation reference design, allowing users to explore the LogiCoA Power Supply Solution using a non-isolated buck converter circuit. This was followed by the launch of the REF67004, a reference design incorporating both PFC and flyback converters – topologies commonly used in consumer and industrial equipment.
The newly introduced REF67004 is a reference design that boosts AC input using a Critical Conduction Mode PFC converter, followed by a Quasi-Resonant Flyback converter to deliver a regulated DC 24V output. Features include a calibration function that compensates for variations in the external component characteristics, enabling the LogiCoA MCU to perform high-precision voltage configuration and overcurrent protection. This allows for reduced design margins, making it possible to select more compact (low power) power devices and inductors, ultimately helping to minimise PCB area and lower overall system costs.
The REF67004 also includes a logging function that allows the LogiCoA MCU to store operational data, such as input/output voltage, current, temperature, pre-shutdown system status, and cumulative operating time, in its built-in non-volatile memory. This data can be analysed to easily identify the root cause of power supply failures. On top, various power control parameters and operational history can be easily configured and retrieved from a PC via UART (with a signal conversion device) using sample programs, including the RMOS (Real-time Micro Operating System) power control OS, available on ROHM’s website. Practical evaluation is possible through the use of the reference design board LogiCoA003-EVK-001. Going forward, ROHM will continue to provide a variety of power supply reference designs to support and accelerate customer power supply development.
