Digital Controllers: Pushing the Limits of Power Control

Aug. 26, 2024

Check out some of the latest real-time MCUs and digital controllers suited for high-density power supplies.

Renesas's RA8T1 family of real-time MCUs run more advanced motor-control and digital power-control algorithms as fast, safely, and securely as possible.

Cortex-M85 MCU Enhanced for Execution of Real-Time Control

Renesas introduced the RA8T1 family of real-time MCUs based on Arm’s Cortex-M85 CPU core to run more advanced motor-control and digital power-control algorithms as fast, safely, and securely as possible.

According to the company, the RA8T1 brings more processing power to the table with the Cortex-M85 clocked at up to 480 MHz, and it takes advantage of Arm Helium technology to enhance its execution of DSP and AI operations and TrustZone to secure it. The chips lend themselves to real-time motor control and digital power supplies that require very fast control-loop computations with multiple sensor inputs. The 32-bit MCU features up to 2 MB of dual-bank flash memory that can be used to upgrade the firmware without interrupting the system.

The RA8T1 incorporates 18-channel PWM timers with a wide range of advanced functions, including three-phase complementary output, duty output capabilities ranging from 0% and 100%, double-buffer compare match register, and several phase-counting modes. The RA8T1 also has up to 1 MB of on-chip SRAM, including 128 kB of tightly coupled memory (TCM) and 512 kB with ECC.

There are also a wide range of analog peripherals: 12-bit ADCs, 12-bit DACs, and high-speed comparators used to measure voltage and current and for protection against short circuits and other overcurrent faults.

It supports SPI, I2C or I3C, CAN or CAN-FD, Ethernet, and USB-FS to interact with other components in the system, including current, voltage, temperature, and other sensors overseeing the power supply’s operation.

Renesas said the RA8T1 MCU is supported by its Flexible Software Package (FSP), giving its customers all of the software and development tools required to roll out advanced motor control and digital power solutions.

Slide 4 of 5

In everything from onboard chargers (OBCs) and DC-DC converters in EVs to the AI power supplies in data centers to solar, wind, and other renewable-energy systems, fully digital power control is trending up. While analog control is widely used in power systems up to 1 kW, it lacks the high level of reliability and accurate control required by modern switch-mode power supplies (SMPS) that are handling more and more power.

As a result, digital power control is becoming more prevalent in both the power factor correction (PFC) and DC-DC converter stages of power converters to help optimize their efficiency, reliability, and robustness. Infineon Technologies, Microchip Technology, Renesas Electronics, and others are trying to tap into the demand for digital power with a new generation of real-time microcontrollers (MCUs) and digital controllers.

These chips bake in high-performance CPU cores with digital signal processing (DSP) and other hardware accelerators that are there to run more advanced power-control algorithms in real-time. These can include adaptive control, which adjusts the control of the power supply based on feedback signals, and predictive control, which can forecast the future operation of the system to avoid undesirable transients or instability.

^{>>Check out the Power Supply Design and Gallium Nitride (GaN) TechXchanges for similar articles and videos.}

TechXchange

Power Supply Design

Examining the challenges and methods of power supply design.

Power

TechXchange: Gallium Nitride (GaN)

GaN is gaining even more ground in the power electronics realm.

They’re also upgrading these digital controllers to handle the faster switching speeds of the latest silicon-carbide (SiC) and gallium-nitride (GaN) power FETs without causing delays, errors, or noise in the control loop. In turn, the chips have tightly integrated interfaces to current, voltage, and other sensors as well as high-precision analog-to-digital converters (ADCs). In addition, high-resolution timers offer tighter control of the pulse-width-modulation (PWM) signals that determine the duty cycle, dead time, phase shift, and switching rate of the power FETs in the system.

One of the pros of digital control is its flexibility. It gives you the ability to adjust the switching frequency and other control parameters by changing the software in the power supply. Digital control also enables more functions and features in the power supply, including fault detection and protection against short circuits or other transients. A rich ecosystem of software development tools is developing around digital power.

In this product roundup, we will run through several of the latest digital power controllers to hit the market:

About the Author

James Morra | Senior Editor

James Morra is a senior editor for Electronic Design, covering the semiconductor industry and new technology trends, with a focus on power electronics and power management. He also reports on the business behind electrical engineering, including the electronics supply chain. He joined Electronic Design in 2015 and is based in Chicago, Illinois.