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 minimize 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 analyzed 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.

　　LogiCoA™ Brand

　　LogiCoA™ is a brand that embodies a design philosophy of fusing digital elements to maximize the performance of analog circuits. By combining the advantages of analog circuitry with those of digital control, it is possible to maximize the potential of circuit topologies, contributing to more efficient power utilization. As LogiCoA™ is a design concept that can be applied not only to the power supply field, but also to power solutions as a whole, ROHM is considering its application in future products and solutions.

　　・LogiCoA™ is a trademark or registered trademark of ROHM Co., Ltd.

　　LogiCoA™ Power Supply Solution Page

　　The basic architecture and key features of the LogiCoA™ Power Supply Solution are available on ROHM’s website.

　　https://www.rohm.com/support/logicoa

　　LogiCoA™ Power Supply Solution Reference Design Lineup

　　In addition to sample software, a variety of tools necessary for evaluation, such as circuit diagrams, PCB layouts, parts lists, and support documents are available on ROHM’s website, while actual device evaluation is also possible using the reference design board. Going forward, ROHM will continue to expand its lineup of reference designs to support a wide range of power topologies.

　　● Reference Design Part No.

　　• PFC + Flyback Converter: REF67004

　　• Buck Converter: REF66009

　　LogiCoA™ MCU  Lineup

　　Key features include a built-in 3ch analog comparator that can be synchronized with timers, along with a D/A converter that enables digital control of various parameters to support different power supply topologies.

　　LogiCoA™ MCU Development Support System

　　Built on a ROHM’s proprietary 16bit RISC CPU core, LogiCoA™ MCUs are fully supported by a dedicated integrated development environment and emulator tools.

　　For more information on the LogiCoA™ development support system and a product overviews, please visit ROHM’s LogiCoA™ MCU development system support page (link below).

　　https://www.rohm.com/lapis-tech/product/micon/logicoa-software

　　Online Sales Information

　　Reference design boards, reference board and LogiCoA™ MCUs are available for purchase through online distributors such as AMEYA360.

　　• Reference Design Board P/N:

　　LogiCoA003-EVK-001*, LogiCoA001-EVK-001

　　• Reference Board P/N:

　　RB-D62Q2035TD20, RB-D62Q2045GD24

　　• LogiCoA™ MCU P/N:

　　ML62Q2035-NNNTDZWATZ, ML62Q2045-NNNGDZW5BY

　　Pricing : $677/unit (samples for LogiCoA003- EVK-001, excluding tax)

　　Application Examples

　　• Industrial robots　• Semiconductor manufacturing equipment　• Gaming devices

　　The LogiCoA™ Power Supply Solution is also suitable for integration into general industrial equipment and consumer devices with power requirements ranging from approximately 50W to 1kW.

　　Terminology

　　Critical Conduction Mode PFC (Power Factor Correction) Converter

　　A configuration used in AC-DC converters within switching power supplies, Critical Conduction Mode PFC offers a high-power factor (indicating efficient utilization of supplied power) while generating less noise compared to Continuous Conduction Mode PFC. A power factor of ‘1’ signifies that all supplied power is being effectively used without waste.

　　Quasi-Resonant Flyback Converter

　　A DC-DC converter topology commonly used in isolated power supply designs, these converters leverage a quasi-resonant control technique to minimize switching losses and noise. Ideal for applications up to 100W, it offers advantages in terms of reduced component count and cost. While other forward-type topologies exist, advancements in the components used in these designs have led to smaller, more efficient isolated power supply solutions.

　　Analog Control Power Supply

　　A power supply configuration built with analog components, commonly used for applications up to 1kW due to its simplicity and low power consumption. However, implementing advanced features such as customizable parameter settings and data logging is challenging with analog control alone, often requiring fully digital solutions that tend to increase both cost and power consumption.

　　Digital Control Power Supply

　　A power supply is managed using digital technology. High-speed CPUs and DSPs are used to precisely monitor and control key parameters such as voltage and current, improving power supply efficiency and reliability. Digital control also enables advanced functions, such as operation log data acquisition, that are difficult to implement with analog control alone. However, CPUs and DSPs tend to be expensive and consume significant power, posing challenges in terms of cost effectiveness and energy efficiency.

　　• CPU (Central Processing Unit): The core processor responsible for executing programs and performing data processing.

　　• DSP (Digital Signal Processor): A processor that converts analog signals into digital form and performs operations such as filtering and amplification.

　　Topology

　　Refers to the circuit configuration. Power topology defines how electrical energy is transformed and managed within a circuit. The specific configuration depends on factors such as input and output voltage levels, power requirements, and whether electrical isolation is necessary.