The RL78/I1C MCUs also retain the measurement accuracy and low power consumption of their predecessors, the RL78/I1B MCUs, of which more than 30 million units have been sold over a three-year period.
 
Renesas developed the RL78/I1C MCUs for smart meters with DLMS support, leveraging the key features of the current RL78/I1B MCU group, with low power consumption and numerous integrated peripheral functions to reduce system cost.
 
The new RL78/I1C MCUs are available in seven versions, with on-chip memory capacities of 64 kilobytes (KB) for low-end single-phase meters, 128 KB for high-end single-phase meters, and 256 KB for three-phase meters; and from 64 pins for space-saving needs, 80 pins for single-phase meters intended for emerging countries, and 100 pins for single-phase meters intended for use in advanced applications.
 
Features of the RL78 / I1C MCUs:
 1) Ability to implement electrical energy measurement processing and DLMS processing on a single chip
The RL78/I1C integrates a hardware AES engine for this purpose. In particular, the RL78/I1C is the first to implement in hardware the AES GCM mode required by the DLMS standard, providing a speed increase of 20 times or more compared to encryption and decryption using software processing in existing Renesas MCUs. Furthermore, the on-chip PLL (Phase-Locked Loop) increases the maximum operating frequency from 24 megahertz (MHz) to 32 MHz, and the 32-bit multiplier unit dramatically reduces the load imposed by software power calculations with 24-bit data converted by the 24-bit ΔΣs A/D converter, resulting in an approximate 30 percent increase in arithmetic throughput. This means that a single chip can handle both power measurement processing and DLMS processing. The RL78/I1C MCUs can perform the processing required to support DLMS communication while simultaneously processing electrical power measurement. Up to 256 KB of on-chip ROM can accommodate program code for both electrical power measurement and DLMS processing. This results in approximately 30 percent reduced power consumption compared to a two-chip configuration and a lower system cost compared to previous two-chip solutions comprised of dedicated power measurement and DLMS processing MCUs.
 
2) Support for three-phase, four-wire meters
The event link controller and phase adjustment functions coordinate the operation of the 24-bit ΔΣ A/D converter and the three-channel 10-bit successive approximation register (SAR) A/D converter. This enables current and voltage measurement across seven channels, as required by three-phase, four-wire meters. The addition of support for three-phase, four-wire meters, in addition to conventional three-phase, single-phase, two-wire, and three-phase meters, allows meter manufacturers to use the RL78/I1C as a common platform for developing various meters for both industrial and consumer applications.
 
In addition, Renesas has extended the features and functionalities of the existing RL78/I1B to the new MCUs, along with improvements to the real-time timer that achieves a standby current consumption of 0.7μA (typical) during operation with an independent power supply, and a power monitoring function with battery backup that allows the CPU and peripheral functions to continue operating even when a power outage occurs.
 
3) Assessment and reference kit
Using the evaluation kit in the initial study phase, it is possible to begin assessing the performance characteristics of the RL78/I1C without actually writing any programs. The reference kit, which includes hardware and drivers for the measurement functions, as well as a highly reliable DLMS library, can be used in the meter development phase to reduce development time by approximately 25 percent compared to independent development, and also to lower costs.
 
 Availability
Samples of the RL78 / I1C are now available.

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