arily targeting conventional meter applications, the 78K0R/LG3-M MCU can be used together with other Renesas power-line and wireless communications solutions to create highly optimized and low cost smart meters.
Through awareness campaigns, consumers have become more conscious of their electricity consumption and the importance of reducing it. The next generation of smart meters will enable this reduction by including integrated LCD displays and bi-directional communication, which will allow remote reading, tariff updates and load balancing through the intelligent control of smart appliances.
Key features of the 78K0R/LG3-M microcontroller
(1) Support for increased meter functionality
To support the increased application requirements of single-phase electricity meters, the 78K0R/LG3-M MCU features 128 KB of embedded Flash memory and 7 KB RAM.
(2) On-chip DSP metrology engine with four second-order precision Sigma Delta 24-bit ADCs (differential input) and a two-channel 10-bit successive approximation ADC.
The metrology engine includes calibration and power calculation functions to free up the main CPU core to manage other application-related tasks. Furthermore, the 78K0R/LG3-M MCU achieves a 0.1 percent active power-measurement error as its power calculation precision, and it conforms to all power meter standards in Japan, Europe and China.
(3) Integration to reduce system costs
To enable meter designers to optimize system costs, the 78K0R/LG3-M MCU integrates several additional peripherals required in metering applications, including:
• Advanced RTC with independent power supply
• Anti-tamper detection circuit to prevent the falsification of power calculations
• Power quality measurement circuit that includes both power outage and current/voltage peak detection functions
• 160-segment LCD driver for the user interface
• Zero-cross and surge-level detection circuits
Many other peripherals are integrated to facilitate system design such as multiple timers, multiple serial interfaces and robust I/O.
(4) Ultra-low power consumption.
With an operating voltage (V) range from 1.8 V to 3.6 V and ultra-low current consumption with the RTC operating, the device offers leading-class power consumption, enabling further cost reduction due to the smaller batteries needed for backup operation if the power fails.