32-bit MCU integrates 24-bit A/D converter, 512KB flash memory

Renesas Electronics Corp. has launched the RX21A group of 32-bit microcontrollers (MCUs) with advanced functions for smart meters.

According to Renesas, the new MCUs are the first in the industry to combine large flash memory capacity of 512 KB and a 24-bit delta-sigma A/D converter for high-resolution measurement.

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.

The RX21A Group of MCUs integrates several other key functions for smart meters, including power measurement, meter control, calculation of electricity charges, and data encryption. 

The operating frequency has been increased to 50 megahertz (MHz), and DSP functions added for filter calculation. The RX21A 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.

Based on the advanced 32-bit RX CPU core, the RX21A MCU achieves 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.

The latest RX21A MCUs include 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 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.