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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