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Power Meter (Single-phase)


Electronic power meter  (Single-Phase)


Electronic power meters have been increasingly adopted world wide as a means, to support AMR (Automatic Meter Reading) and AMI (Advanced Meter Infrastructure), and to reduce fraudulent use of electricity. Recently, energy-saving and eco-friendly products are becoming popular. The use of smart meters, which control household equipment, is expanding with the goal of realizing a smart grid that will enable the energy efficiency of a geographical area to be improved. As power meters become a communication gateway to the home, they are becoming more advanced in both their performance and functionality.

A power meter must operate on its internal battery from when it leaves the factory to when it is installed at its final destination. Low-power consumption is essential when only the real-time clock (RTC) is running. Also needed are each communication interface for AMR and AMI support, infrared communication for meter reading, and data transfer to and from prepaid cards.

Renesas has a rich lineup of control microcontrollers for single-phrase meter.  The 78K0/Lx3-M, 78K0R/Lx-3, and RX21A Group with a built-in 24-bit ΔΣ(delta-sigma) ADC help to reduce costs and external components. Renesas offers low-cost and low power consumption microcontrollers such as the RL78/L1x, RX210, and RX220 when using an external ΔΣADC. Renesas also, offers a lineup of microcontrollers with built-in ZigBee/IEEE802.15.4 and Power Line Communication (PLC) functions essential to smart meter.

Within the MCU lineup of Renesas, the 78K0R/Lx3 and the R8C/Lx Series implements three UART channels on-chip, enabling a variety of communication formats used by smart meters, and its integrated RTC operates on very little power. It is also equipped with large-capacity memory, making possible more sophisticated smart meter functions. Additional integrated functions include an on-chip oscillator (OCO), a watchdog timer (WDT), and an LCD drive control circuit. These reduce the number of external parts needed and helping to reduce the overall system cost.


System Block Diagram (Main control block)


System Block Diagram (Main control block)


System Block Diagram (Sensor and power supply block)


Recommended Products

Block Semiconductor device Recommended products Features, etc.
Control MCU
(ΔΣADC integrated)
8-bit CPU, 24-bit ΔΣADC, LCD driver,
power calculation circuit

16-bit CPU, 24-bit ΔΣADC, LCD driver,
power calculation circuit

RX21A Group 32-bit CPU, high capacity memory, DataFlash
24-bit ΔΣADC (7units, SNDR 85dB) 
MCU R8C/Lx Series LCD driver, low power consumption
RL78/L1x LCD driver, ultra low power consumption
RX210 Group 32-bit CPU (50MHz max), high capacity memory
RX220 Group 32-bit CPU (32MHz max), low pin count
EEPROM R1EX24xxx Series I2C bus interface *1
R1EX25xxx Series SPI bus interface *2
RS485 signal I/F Photocoupler
PS23xx Series
PS27xx Series
PS28xx Series
High isolation voltage (5kVr.m.s.), 4p-LSOP, Ta=115°C
High isolation voltage (3.75kVr.m.s.), 4p-SOP, Ta=110°C
High isolation voltage (2.5kVr.m.s.), 4p-SSOP, Ta=110°C
PS91xx Series
PS93xx Series
PS98xx Series
(Small SOP)
PS99xx Series
Digital output   
Low supply current

*1 I2C: Inter-Integrated Circuit
*2 SPI: Serial Peripheral Interface

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