It combines an analogically controlled power stage circuit with ROHM silicon MOSFETs and gate control ICs with a digitally managed power supply circuit built around the low-power LogiCoA™ MCU . (Figure 1)

Rohm logical reference design

Analog-controlled power supplies are used in small- and medium-power industrial applications, such as industrial robots and semiconductor manufacturing equipment. However, increasing demands for greater reliability and more precise control have made it increasingly difficult for purely analog configurations to meet market expectations. On the other hand, while fully digital power supplies offer precise control and greater flexibility, their adoption in the small- and 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 analog and digital control. Combined with ROHM's high performance, the low-power LogiCoA™ MCUs enable the control of various power topologies. As a first step, ROHM released the REF66009 evaluation reference design, which allows users to explore the LogiCoA™ power supply solution using a non-isolated buck converter circuit. This was followed by the release of REF67004, a reference design that incorporates PFC and flyback converters, topologies commonly used in consumer and industrial equipment.

The new REF67004 is a reference design that boosts the AC input using a critical conduction-mode PFC converter, followed by a quasi-resonant flyback converter to provide a regulated 24V DC output. Features include a calibration function that compensates for variations in the characteristics of external components, enabling the LogiCoA™ MCU to perform high-precision voltage setting 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 the printed circuit board area and reduce overall system costs.

The REF67004 also includes a logging function that allows the LogiCoA™ MCU to store operating data, such as input/output voltage, current, temperature, system state before shutdown, and accumulated operating time, in its onboard non-volatile memory. This data can be analyzed to identify the root cause of power supply failures. Furthermore, various power control parameters and operating history can be configured and retrieved from a PC via UART (using a signal converter) with sample programs, including the RMOS (Real-time Micro Operating System) power control operating system, available from the ROHM website. A hands-on evaluation can be performed using the LogiCoA003-EVK-001 reference design board.


LogiCoA™ brand
embodies a design philosophy that merges digital elements to maximize the performance of analog circuits. By combining the advantages of analog circuits with those of digital control, it is possible to maximize the potential of circuit topologies, contributing to more efficient energy utilization. Since LogiCoA™ is a design concept applicable not only to the field of power supplies 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 Solutions Page
The basic architecture and main features of the LogiCoA™ power solution are available on the ROHM website: https://www.rohm.com/support/logicoa

LogiCoA™ Power Solution Reference Design Range.
In addition to the sample software, various tools necessary for evaluation, such as circuit diagrams, PCB layouts, parts lists, and supporting documentation, can be found on the ROHM website, while actual device evaluation is also possible using the reference design board. (Figure 2)

In the future, ROHM will continue to expand its range of reference designs to support a wide range of power topologies.
• Reference design reference number
• PFC and flyback converter: REF67004
• Step-down converter: REF66009

LogiCoA™ MCU Range.
Key features include an integrated 3-channel 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. (Figure 3)

LogiCoA™ MCU Development Support System
Based on a ROHM-exclusive 16-bit RISC CPU core, LogiCoA™ MCUs are fully compatible with a dedicated integrated development environment and emulation tools.

For more information about the LogiCoA™ development support system and a product overview, please visit ROHM's LogiCoA™ MCU development system support page. 

• 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

Application examples
• Industrial robots
• Semiconductor manufacturing equipment
• Gaming devices
TM power solution is also suitable for integration into general industrial equipment and consumer devices with power requirements ranging from approximately 50 W to 1 kW.