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Renesas Electronics Introduces 32-Bit RX21A Group of Microcontrollers with Large Memory Capacity and Built-In A/D Converter Enabling High-Resolution Measurement for Highly-Functional Smart Meters
[September 06, 2012]

Renesas Electronics Introduces 32-Bit RX21A Group of Microcontrollers with Large Memory Capacity and Built-In A/D Converter Enabling High-Resolution Measurement for Highly-Functional Smart Meters

SANTA CLARA, Calif. --(Business Wire)--

Renesas Electronics Corporation (TSE: 6723), a premier supplier of advanced semiconductor solutions, today announced the RX21A Group of 32-bit microcontrollers (MCUs) for smart meters with advanced functionality. The new MCUs are the first in the industry to combine large flash memory capacity of 512 KB and a 24-bit delta-sigma (Delta-sigma) A/D converter (Note 1) for high-resolution measurement.

RX21A chip shot

RX21A chip shot

The RX21A Group of MCUs implements in a single chip functions that previously required separate devices, such as power measurement, meter control, calculation of electricity charges, and data encryption. This reduces the number of external components required and helps to lower the overall cost. In addition, the RX21A Group includes product versions for a variety of meter models, allowing common and effective system design.

"As we continue to move toward a more energy efficiency society, "green" or "smart" solutions like smart meters will require innovative peripherals at the chip level which includes but is not limited to the high-precision analog, low power consumption and multiple connectivity options. In addition, customers would benefit from the unified set of peripheral drivers conforming to the safety standards," said Ritesh Tyagi, Senior Director, Microcontroller Products & Solutions Marketing, Renesas Electronics America. "The new RX21A group of MCUs represents the latest example of how Renesas brings smart design to these growing markets, leveraging our low-power and advanced technology roots."

Recently, the smart meter market has expanded rapidly with the spread of smart grids as a way to increase energy efficiency. It is estimated that more than 100 million smart meters will be in operation by 2014. The proliferation of smart meters has created demand for MCUs that provide, in addition to reduced power consumption, higher performance to support advanced functions such as complex power calculation, needed for time-of-day rate systems and other diverse power services in many countries, and strong security, including communication data protection and unauthorized access prevention, in addition to reduced power consumption. There is also a greater need for shorter development cycles and improved development efficiency for new meter models, which spurs the need for an extensive lineup of MCUs supporting a wide range of smart meter models. At the same time, the home energy management system (HEMS) market is growing rapidly, driving the trend toward MCUs with enhanced functionality and larger memory capacity.

Renesas already mass produces 8-bit and 16-bit MCUs with on-chip Delta-sigma A/D converters for use in power meters with power calculation and ordinary billing capabilities. The RX21A Group of MCUs expands the product lineups to further meet the market demands. Renesas now offers a full range of Delta-sigma A/D converter-equipped MCU product lineups, allowing designers to scale from the low-end to high-end smart meters more easily.

Key features of the new RX21A Group of MCUs:

(1) On-chip peripheral functions for meters, such as 24-bit Delta-sigma A/D converter and encryption engine

The RX21A Group of MCUs integrates a newly-developed 24-bit Delta-sigma A/D converter module that delivers higher resolution than the 16-bit module of existing MCU products. The new MCUs incorporate in a single chip all the main functions required by smart meters, including encryption engine, real-time clock (RTC) with tamper, temperature sensor, and IrDA.3 (Infrared Data Association). This reduces the total number of components required and lowers the overall system cost.

The 24-bit Delta-sigma A/D converter achieves conversion accuracy (SNDR) of 85 dB, and the encryption engine supports AES (256-bit key length). This provides smart meters with improved calculation precision and enhanced security functionality, such as communication data protection and unauthorized data access prevention that will be needed for the next-generation smart meters.

(2) High-performance CPU and large memory capacity to support advanced-functionality smart meters

In addition to the performance boost moving from the existing Delta-sigma A/D converter-equipped 16-bit MCUs to a 32-bit architecture, the operating frequency of the RX21A Group of MCUs has been increased to 50 megahertz (MHz), and DSP functions added for filter calculation. The RX21A Group of MCUs also has a large on-chip flash memory with a capacity of up to 512 KB, twice that of Renesas' existing products, to accommodate larger programs.

(3) RX CPU and low-power peripheral functions for the system's overall reduced power consumption

The new RX21A Group of MCUs is part of the RX200 MCU series that brings new levels of capability and performance to ultra-low-power, low-voltage embedded-system applications. Based on the advanced 32-bit RX CPU core, the RX21A Group of MCUs achieves the industry-leading power consumption of 0.2 mA/MHz. Power consumption in standby mode is only 1.0 microampere (µA) when the RTC is operating and 0.3 µA when the RTC is stopped. These enhancements enable system designers to develop smart meters with reduced power consumption and smaller backup batteries.

(4) Nine product versions to support wide range of power meters, such as single-phase and poly-phase models

The new RX21A Group of MCUs includes product versions with three, four, and seven 24-bit Delta-sigma A/D converter channels to accommodate both single-phase smart meters, and poly-phase smart meters. System designers can choose from three on-chip flash memory capacities, 256 KB, 384 KB, and 512 KB, to accommodate the differing billing and communication systems in various countries and regions. The nine product versions in total support a variety of meter models, allowing common system design and a shortened development cycle.

Renesas plans to supply a development support environment, including middleware for power measurement and calibration tools, for the new RX21A Group of MCUs. The company will also provide one-stop kit solutions combining the new MCUs with devices such as the PS2513/14 photocouplers to insulate the MCU from the communication interface in smart meter applications.

(Note 1) Delta-sigma A/D converter: A module that converts analog data into digital form by delta-modulation of a bit stream generated by oversampling the analog signal, after which integration processing and filtering are used to eliminate noise. As of June 28, 2012 the RX21A Group is the first in the industry to combine a 32-bit CPU, 512 KB or more on-chip flash memory, and a 24-bit Delta-sigma A/D converter (source: Renesas).

Refer to the separate sheet for the main specifications of the RX21A Group of MCUs.

Pricing and Availability

Samples of Renesas' RX21A Group of MCUs are available now, priced at US$5.07 per unit when ordered 10,000 units. Mass production is scheduled to begin in December 2012 and is expected to reach a combined volume of 500,000 units per month. (Pricing and availability are subject to change without notice.)

All other registered trademarks or trademarks are the property of their respective owners.

Separate Sheet

Product Specifications of the RX21A Group


RX21A Group

Pin 64-pin 80-pin 100-pin
Part No. R5F521AxxDFM R5F521AxxDFN R5F521AxxDFP
Maximum operating frequency / Voltage range 50MHz : VCC=2.7 to 3.6V
25MHz : VCC=1.8 to 3.6V
ROM 256KB, 384KB, 512KB
E2 Data Flash 8KB
RAM (News - Alert) 32KB, 64KB
24-bit ?S A/D converter (SNDR=85dB) 3 ch 4 ch 7 ch
Data encryption unit Yes
Real time clock Yes
Serial peripheral interface 2 ch
Serial communications interfaces 5 ch (including one channel for IrDA)
I2C bus interface 1 ch 2 ch 2 ch
Event link controller Yes
Multi-function pin controller Yes
DMA controller 4 ch
Data transfer controller Yes
Multi-function timer pulse unit 2 16-bit × 6 ch
Port output enable2 5
8-bit timer 8-bit 4ch
Compare match timer 16-bit 4ch
CRC calculator Yes
Data operating circuit Yes
10-bit A/D converter 4 ch 7 ch 7 ch
D/A converter No 2 ch 2 ch
Voltage detection Yes
Comparator 3 ch 4 ch 4 ch
Safety functions Independent Watchdog Timer, Clock-Accuracy Check: etc
Clock Main clock oscillator, sub-clock oscillator
Internal Clock low-speed on-chip oscillator, high-speed on-chip oscillator
Current consumption Normal operation (CPU-Core) : 0.2mA/MHz*2
Deep software standby mode (with RTC operation) : 1.0uA*2
Delta-sigma A/D Convertor : 1mA/ch*2
Operating temperature -40? to +85?, -40? to +105?
Package LQFP (0.5mm pitch)

*1: "xx" differs depending on package type
*2: Target (News - Alert) value

About Renesas Electronics Corporation

Renesas Electronics Corporation (TSE: 6723), the world's number one supplier of microcontrollers, is a premier supplier of advanced semiconductor solutions including microcontrollers, SoC solutions and a broad-range of analog and power devices. Business operations began as Renesas Electronics in April 2010 through the integration of NEC (News - Alert) Electronics Corporation (TSE:6723) and Renesas Technology Corp., with operations spanning research, development, design and manufacturing for a wide range of applications. Headquartered in Japan, Renesas Electronics has subsidiaries in 20 countries worldwide.

More information about Renesas products can be found at

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