Greener BeeGreen ElectronicsRenesas Electronics Introduces 32-Bit RX21A Group of Microcontrollers with Large Memory Capacity and Built-In A/D …

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

“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
, 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

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





Part No.






Maximum operating frequency / Voltage range

50MHz : VCC=2.7 to 3.6V
25MHz : VCC=1.8 to 3.6V


256KB, 384KB, 512KB

E2 Data Flash



32KB, 64KB

24-bit ΔΣ A/D converter (SNDR=85dB)

3 ch

4 ch

7 ch

Data encryption unit


Real time clock


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


Multi-function pin controller


DMA controller

4 ch

Data transfer controller


Multi-function timer pulse unit 2

16-bit × 6 ch

Port output enable2


8-bit timer

8-bit 4ch

Compare match timer

16-bit 4ch

CRC calculator


Data operating circuit


10-bit A/D converter

4 ch

7 ch

7 ch

D/A converter


2 ch

2 ch

Voltage detection



3 ch

4 ch

4 ch

Safety functions

Independent Watchdog Timer, Clock-Accuracy Check: etc


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℃


LQFP (0.5mm pitch)


*1: “xx” differs depending on package type
*2: Target 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
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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