24-bit ΔΣ A/D converter, RTC backup and high-accuracy oscillator combine to introduce RL78 low power microcontrollers to electricity meter market

RL78/I1B microcontrollers adapt various electricity meter metrologies for different regulations by country and realize the efficient power measurement by the combination of low active current 96uA/MHz, standby current 0.66uA (Halt mode with 32kHz oscillator and RTC backup on), 24-bit ΔΣA/D converter, phase adjustment circuits and high pass filter. CPU clock frequency can be minimized taking advantage of the efficient power measurement features, which includes the low power ΔΣ A/D converter 0.53mA/ch. RL78/I1B microcontrollers have +/- 1% high-accuracy high-speed on-chip oscillator with +/-0.05% frequency correction function and keep the system robust by the benefit of the accurate on-chip oscillator even when the external oscillator is stopped.

Key Features:

Memory CODE FLASH 128 KB 64 KB 128 KB 64 KB
RAM 8 KB 6 KB 8 KB 6 KB
24-bit ΔΣ A/D Converter SNDR ~80 dB(x1)
Analog input voltage ±0.500 V(x1)
Sampling frequency 3.906 kHz/1.953 kHz
Programmable gain amplifier Current channels x1~x32 ・Voltage channels x1~x16
Internal refernce voltage Yes
Channels 3 channels 4 channels
8/10-bit SAR A/D Converter Channels 4 channels 6 channels
Temperature sensor 1 channel 1 channel
LCD Controller/Driver Segment/Common 30 seg. x 8 com. 38 seg. x 8 com.
(32 seg. x 6 com., 34 seg. x 4 com.) (40 seg. X 6 com., 42 seg. X 4 com.)
Method Internal voltage boosting method / capacitor split method / external resistance division
Real time clock Error correction function Yes
Error correction resolution 0.96 ppm
1 Hz output 1 channel
Infrared data communication 1 channel
Comparators 2 channels
Battery backup function (VBAT) Yes
Package Pin count / package 80 pin LQFP (12mm) 100 pin LQFP (14mm)
Current consumption (typ.) Normal operation A/D Converter 3 channels
RTC backup mode operation 0.66 uA

Pin Count / Memory Size Lineup:

Program Flash


Block Diagram:




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Software Design Support

Title Description
e² studio This integrated development environment (IDE) is based on the popular combination of the open-source Eclipse IDE and its CDT plug-in that enables C/C++ language development.
CS+ This integrated development environment (IDE) can be used for coding, assembly, compiling, and simulation. CS+ is also included with starter kits.
E2 emulator Lite This entry-level on-chip debugging emulator provides functionality equivalent to that of the E1 emulator at a low price.
E2 emulator This on-chip debugging emulator has advanced features that improve the efficiency of development. In addition to the basic functions from debugging to flash programming, this emulator supports hot plug-in and external triggers as standard items. This emulator also helps to reduce development time by downloading at high speeds (compared to the E1 emulator) and the ability to work in combination with various solutions such as the tuning of current drawn by systems under development.
E1 emulator This on-chip debugging emulator is a standard model which provides basic debugging functions (production is to be discontinued at the end of December 2019).

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