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# 3.3 Energy Metering Analog Front End (EMAFE)

The Energy Metering Analog Front End (EMAFE) peripheral embeds five high-resolution Sigma-Delta Analog-to-Digital converters followed by SINC decimation filters. The current measurement channels feature a low noise programmable gain amplifier to accommodate any type of current sensor configured in any type of IEC/ANSI-C application. One of these channels may be dedicated to neutral current measurement to implement anti-tamper functions.

The EMAFE embeds a high-performance voltage reference and a die temperature sensor. The temperature characteristics of these functions are measured during manufacturing and stored in an internal read-only memory. A low-cost and efficient voltage reference temperature correction can then be implemented at software level and is part of the standard Microchip ANSI and IEC Metrology compliant library.

The EMAFE processes the output data of the five simultaneously sampled Sigma-Delta ADCs. The output of ADCs are pre-filtered and the data transfer to system memory can be performed with a parallel access or a serial access.

The processor can be configured to perform serial or parallel access to collect the pre-filtered ADCs output data. The direct memory access module (PDC) can be configured to collect the pre-filtered ADC output data with minimal CPU intervention.

In addition, the EMAFE embeds several hardware comparators and predefined thresholds to perform on-the-fly comparisons and report interrupts.

The EMAFE can monitor the difference between two configurable channels and report an interrupt if the difference is above a configurable threshold.

It is possible to report an interrupt when there is a change in the value of a configurable channel. The amount of change is configurable. This Comparison mode is useful for channels that vary at a slow rate (e.g., temperature).

Rev: E