General Description
The AS8218 / AS8228 are highly integrated CMOS single-phase energy metering devices for fully electronic LCD meter systems. The AS8218 / AS8228 have been designed to ensure that meters can fully comply with the international Standards IEC1036 and ANSI.

KEY FEATUREs
- Precision single-phase, one or two current input energy measurement front-end including SigmaDelta modulators for A/D-conversion and digital signal processor (DSP).
- Low current consumption of 5mA, depending on MCU activity.
- Digital phase correction and selectable gain on both current channels for use with two current transformers (CT) or one CT and one shunt.
- Power-supply monitor (PSM) for power-on reset and reset when the supply voltage falls below a defined threshold.
- Customer programmable 8-bit 8051 compatible microcontroller (MCU).
- Programmable MCU clock with optional low power operating conditions.
- 2 x Universal Asynchronous Receiver / Transmitters (UART) for external communications such as programme download and debugging.
- Real-time clock/calendar (RTC) with on-chip digital calibration and separate battery backup pin.
- On-chip voltage reference (VREF) with small temperature coefficient.
- Low power 3.0 – 4.0MHz crystal oscillator.
- SPI compatible interface for external EEPROM memory.
- Standard on-chip LCD driver (LCDD) interface.
- Programmable multi-purpose I/Os (MPIO) with selectable data direction, pull-up or pull-down resistors and drive strength.
- Low power battery operating mode for meter reading when Mains voltage is not present.
- The difference between the AS8218 and AS8228 ICs are:
    AS8218: 20 x 4 segment LCDD 9 x multi-purpose I/O (MPIO)
    AS8228: 24 x 4 segment LCDD 12 x multi-purpose I/O (MPIO)