Rohm Blends Analog and Digital for Optimal Power Control

LogiCoA provides digital precision with power consumption equivalent to analog power supplies.

Traditional analog-controlled power supplies, commonly used in robotics and semiconductor manufacturing, offer reliability but tend to fall short of delivering the fine control and efficiency required in modern applications. On the other hand, fully digital power supplies provide advanced control capabilities but come at a higher cost and power consumption. 

To address this challenge, Rohm Semiconductor has introduced LogiCoA, the “industry's first” analog-digital fusion control power supply solution. The product aims to strike the right balance between analog and digital control electronics. 

Reference design board for LogiCoA. Image used courtesy of Rohm

Analyzing Pros and Cons

Analog power supplies, based on components like linear regulators and analog controllers, are valued for their simplicity, reliability, and robustness. Additionally, due to their continuous analog feedback, they tend to offer fast response times and stable performance under various conditions. 

However, analog electronics face limitations in precision and flexibility, as they often struggle with efficiency across different loads and input voltages. Analog systems also require larger components, which results in bulkier and larger systems. For these reasons, analog power supplies tend to be the choice for systems up to 1kW.

In contrast, digital power supplies use digital controllers and digital signal processors (DPS). They offer superior precision, flexibility, and efficiency compared to analog solutions, thanks to advanced algorithms and the capability for real-time adjustments. Digital power supplies can also leverage real-time sensor data to monitor variables like temperature and fan performance, enabling dynamic adjustments to continuously optimize performance. 

Despite these benefits, digital systems face challenges such as higher costs and potential susceptibility to electromagnetic interference. Overall, the real challenge for power designers is achieving high precision, flexibility, and efficiency without sacrificing simplicity or cost.

Hybrid Power Control

Rohm aims to address these challenges with its LogiCoA power supply solution, which integrates the benefits of both technologies into a single solution. 

The LogiCoA power supply combines a digital control block with analog components to merge digital control’s precision with analog circuitry’s robustness. The system mitigates the cost issues associated with digital systems by replacing high-speed CPUs and DPSs with low-bit MCUs. It relies on the Rohm LogiCoA MCU, which offers features including three-channel comparators, built-in ADCs, DACs, and programmable amplifiers around a 16 MHz, 16-bit RISC CPU core.

Rohm LogiCoA power supply solution overview. Image courtesy of the Rohm

This design allows for a low-cost system that can use advanced features such as real-time adjustments, storing current and voltage values in the MCU's nonvolatile memory, and logging operation data for industrial applications. 

For these reasons, Rohm states that the LogiCoA system is best suited for small to medium power applications (30 W to 1k W). Target applications include industrial robots, semiconductor manufacturing equipment, and gaming applications.

Electronics for the Future

By merging the strengths of analog and digital systems, Rohm’s power supply could be a promising contender in small-to-medium power applications. To help designers, the company offers reference designs such as the REF66009 and evaluation kits such as the LogiCoA001-EVK-001.