Energy Metering Ic With On-chip Fault Detection - Analog Devices

The ADE7751 is a high-accuracy, fault-tolerant electrical energy measurement IC that is intended for use with 2-wire distribution systems. The part specifications surpass the accuracy require- ments as quoted in the IEC1036 standard. The only Analog circuitry used in the ADE7751 is in the ADCs and reference circuit. All other signal processing (e.g., multipli- cation 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 ADE7751 incorporates a novel fault detection scheme that warns of fault conditions and allows the ADE7751 to continue accurate billing during a fault event. The ADE7751 does this by continuously monitoring both the phase and neutral (return) currents. A fault is indicated when these currents differ by more than 12.5%. Billing is continued using the larger of the two currents. The ADE7751 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. The ADE7751 includes a power supply monitoring circuit on the AVDD supply pin. The ADE7751 will remain in a reset condition until the supply voltage on AVDD reaches 4 V. If the supply falls below 4 V, the ADE7751 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 matched whether the HPF in Channel 1 is on or off. The ADE7751 also has anticreep protection. The ADE7751 is available in 24-lead DIP and SSOP packages. By Analog Devices, Inc.