Single phase for LCD energy meter ICs – provide best in class performance


Single phase for LCD energy meter ICs – provide best in class performance

The AS8218 and AS8228 ICs from austriamicrosystems include all the functional requirements for 1-phase LCD energy meters. The precision measurement front end which ensures best in class performance. The AS8218 and AS8228 precision energy measurement front-end comprises the analog front-end (AFE) and digital signal processor (DSP) which enables precision accuracy performance of better than Class 0.1 over a dynamic range of greater than 1000:1.

The AFE has three analog inputs for measuring the mains voltage, and both the phase and neutral currents. The voltage and current inputs provide for full bidirectional energy measurement. This ensures that the meter can measure and record energy when all the tamper connection configurations are applied, including incoming and outgoing interchanged, phase and neutral interchanged and load is connected to earth, as well as combinations of these.

Furthermore, when current is measured and the mains voltage signal is not available for calculation, the DSP provides for a simulated mains voltage input to ensure that consumption can still be metered, thus incorporating all the anti-tamper requirements specified by utility companies. The on-chip 8-bit 8051 microcontroller enables the recording of tamper conditions and the real-time clock/ calendar provides the time and date stamp for such vents.

The multi-purpose inputs/outputs (MPIO) are fully programmable for data direction, pull-up or pull-down resistors and for current drive strength. This allows for direct connection of LEDs for the display of current reversal, phase availability and load to earth connection, besides all other standard display requirements such as LED pulse output for calibration and consumption monitoring. The fully programmable on-chip liquid crystal display driver (LCDD) can also be used for the display of the various tamper conditions.

The AS8218 IC provides for an 80-segment LCD display and has nine independently programmable inputs/outputs; the AS8228 IC provides for a 96-segment LCD display and 12 programmable inputs/outputs. These ICs far surpass the utility specification requirements laid out in the IEC6052 and ANSI standards and require a minimum of external components.