Date: 10/09/2012

32 bit MCU from Renesas measure, control and calculate energy in smart meter

Renesas Electronics has announced the new RX21A Group of 32-bit microcontrollers (MCUs) for smart meters with on-chip flash memory up to of 512 KB and a 24-bit delta-sigma ADC for high-resolution measurement. The RX21A Group of MCUs has on-chip support for power measurement, meter control, calculation of electricity charges, and data encryption.

Detailed explanation by Renesas on the features of the new RX21A Group of MCUs includes:
(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.

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.)