Renesas Electronics RX21A 32-bit microcontrollers (MCUs) for smart meters

The Renesas Electronics RX21A 32-bit microcontrollers (MCUs) for smart meters combine large flash memory capacity of 512 KB and a 24-bit delta-sigma A/D converter for high-resolution measurement.

In a single chip, the RX21A series implements 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.

The RX21A MCUs have on-chip peripheral functions for meters, such as a 24-bit Delta-sigma A/D converter and an encryption engine which delivers higher resolution than the 16-bit module of existing MCU products. It incorporates a real-time clock (RTC) with tamper, temperature sensor and IrDA.3. 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).

The RX21A Group of MCUs is part of the RX200 MCU series which offers ultralow-power and low-voltage embedded-system applications. Based on the advanced 32-bit RX CPU core, the RX21A MCUs achieve a consumption of 0.2 mA/MHz. Power consumption in standby mode is only 1.0 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.

Nine product versions are available to support a wide range of power meters. Variants include single-phase and poly-phase models; three, four and seven 24-bit Delta-sigma A/D converter channels. System designers can also choose from three on-chip flash memory capacities - 256, 384 and 512 KB - to accommodate the differing billing and communication systems in various countries and regions.