Renesas Electronics Improves Energy Efficiency with Precision Control Solution for Home Appliances, Industrial and Office Equipment

32-Bit RX23T Microcontrollers Feature On-Chip Floating Point Unit, Reducing Code Size and Development Time by 30 Percent

TOKYO, Japan,  Renesas Electronics Corporation (TSE: 6723), a premier provider of advanced semiconductor solutions, continues to develop embedded solutions that contribute to a reduced energy footprint. Today, the company introduced the RX23T Group of microcontrollers (MCUs), designed to enable highly precise control of inverter circuits employed in energy-efficient electric home appliances, industrial machinery, and office equipment. Based on the fast RX core, the new 32-bit MCUs are ideal for building high-performance inverter control systems for applications such as DC motor control in energy-efficient electric home appliances such as refrigerators, air conditioners, washing machines, vacuum cleaners, and fans; entry-level to mid-range industrial equipment such as general-purpose inverters, electrical tools, and drones; and office equipment. The functions are optimized for single inverter drive, including the inclusion of an on-chip floating point unit (FPU) that reduces code size and development time both by 30 percent.

Energy efficiency regulations have become stricter in many countries in recent years, expanding to include entry-level and mid-range energy-efficient electric home appliances and industrial equipment. System designers in these price-competitive markets are looking for new approaches to achieve the reduced power consumption desired within increasingly constrained budget requirements for energy-efficient, cost-attractive products. The demand for more compact, more highly efficient, and quieter motors in office equipment such as printers and multifunction units has led to a move away from stepping motors and toward the adoption of brushless DC motors. There is a need for more highly precise position control without increased system cost.

To respond to these market demands for improved energy efficiency, more precise control, and lower development cost, Renesas has developed the RX23T Group of MCUs, offering an excellent cost-to-performance ratio. The new MCUs provide an optimized subset of the functions of the RX62T Group, which has a proven track record in the inverter control field, designed specifically for use in single inverter drive applications.

Key Features of the RX23T Group of MCUs:

  • (1) Highly precise inverter control and reduced development time for mid-range and entry-level devices

    Inverter control requires a large number of arithmetic operations involving decimal points, and it is useful to perform these using a floating-point arithmetic unit. However, cost constraints on mid-range and affordably priced power-efficient electric home appliances and industrial equipment have prevented the use of expensive microcontrollers with on-chip FPUs. Instead, the most common approach has been to develop software for a fixed-point arithmetic unit. The new RX23T Group MCUs incorporate an on-chip FPU without increased costs, eliminating the need to implement the decimal position shifting required when using a fixed-point arithmetic unit. This simplifies the software configuration and can reduce code size and development time by as much as 30 percent. The on-chip peripheral functions are also optimized for single inverter drive, boosting the cost-to-performance ratio and making it possible to add high-precision inverter control to mid-range and entry-level products.

  • (2) High power efficiency among the best in the industry for even lower power consumption in inverter products

    The RX23T MCUs feature the RXv2 core (4.0 CoreMark/MHz (target), among the best in the industry) and digital signal processing (DSP) functionality, allowing operation processing to be maintained with no loss of real-time responsiveness when performing inverter control (sensor-less vector control), even when the CPU is not running at high speed. In addition, current consumption in low-power mode (data retained in RAM) is only 450 nA (typ.).This power efficiency is among the best in the industry, enabling inverter products with lower power consumption.

  • (3) Support for 5 V peripheral I/O, making it easier to implement measures to reduce effects of electromagnetic noise from inverter drive

    As systems become more power efficient and the power supply voltage drops, it becomes necessary to take steps to prevent electromagnetic noise from peripheral components from adversely affecting high-precision control because MCUs become more susceptible to such interference when the power supply voltage is low. Supporting a 5 V power supply voltage, the new RX23T Group MCUs are less vulnerable to inverter drive noise than MCUs using a 3 V power supply, reducing the number of components required to reduce the noise effects.

  • (Note 1) FPU (Floating Point Unit):
    A type of functional unit designed specifically to perform floating point arithmetic operations.
  • (Note 2). DSP (Digital Signal Processing):
    A functionality provided by a processor that performs digital signal processing. It converts continuous analog signals into discrete digital signals and performs operation processing, making it possible to extract the desired signal elements (information).

Refer to the separate sheet (PDF: 78 KB) for the main specifications of the RX23T Group of MCUs.

Pricing and Availability

Samples of the 12 RX23T MCUs are available now in package pin counts ranging from 48 to 64 pins and on-chip flash memory capacities ranging from 64 to 128 kilobytes (KB) for a total of 12 individual products. Pricing varies depending on memory capacity, number of pins, and package. For example, the R5F523T3ADFL with 64 KB of flash equipped in a 48-pin QFP package is priced at US$1.25 per unit in 10,000-unit quantities. Mass production is scheduled to begin in August 2015 and is expected to reach a scale of 500,000 units per month in July 2016. Integrated development environment (CS+, e2 studio) and code generator support tools are scheduled to be available from June 2015. Renesas also plans to expand the lineup of motor control application notes and solutions. (Pricing and availability are subject to change without notice.)

Roadmap of Renesas MCUs for Inverter Control Systems

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