AD7755

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.

The AD7755 supplies average real power information on the low frequency outputs F1 and F2. These logic outputs may be used to directly drive an electromechanical counter or interface to an MCU. The CF logic output gives instantaneous real power information. This output is intended to be used for calibration purposes, or interfacing to an MCU.

The AD7755 includes a power supply monitoring circuit on the AVDD supply pin. The AD7755 will remain in a reset condition until the supply voltage on AVDD reaches 4 V. If the supply falls below 4 V, the AD7755 will also be reset and no pulses will be issued on F1, F2 and CF.

Internal phase matching circuitry ensures that the voltage and current channels are phase matched whether the HPF in Channel 1 is on or off. An internal no-load threshold ensures that the AD7755 does not exhibit any creep when there is no load.

The AD7755 is available in 24-lead DIP and SSOP packages.