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.