GENERAL DESCRIPTION

The AD7755 is a high accuracy electrical energy measurement IC. The part specifications surpass the accuracy requirements as quoted in the IEC1036 standard. See Analog Devices’ Application Note AN-559 for a description of an IEC1036 watt-hour meter reference design.

The only analog circuitry used in the AD7755 is in the ADCs and reference circuit. All other signal processing (e.g., multiplication and filtering) is carried out in the digital domain. This approach provides superior stability and accuracy over extremes in environmental conditions and over time.

FEATURES

High Accuracy, Supports 50 Hz/60 Hz IEC 687/1036 Less than 0.1 Error Over a Dynamic Range of 500 to 1

The AD7755 Supplies Average Real Power on the Frequency Outputs F1 and F2

The High Frequency Output CF Is Intended for Calibration and Supplies Instantaneous Real Power

The Logic Output REVP Can Be Used to Indicate a Potential Miswiring or Negative Power

Direct Drive for Electromechanical Counters and Two Phase Stepper Motors (F1 and F2)

A PGA in the Current Channel Allows the Use of Small Values of Shunt and Burden Resistance

Proprietary ADCs and DSP Provide High Accuracy over Large Variations in Environmental Conditions and

Time

On-Chip Power Supply Monitoring

On-Chip Creep Protection (No Load Threshold)

On-Chip Reference 2.5 V 6 8 (30 ppm/8C Typical) with External Overdrive Capability

Single 5 V Supply, Low Power (15 mW Typical)

Low Cost CMOS Process