The ADE7759 is an accurate active power and energy measurement IC with a serial interface and a pulse output. The ADE7759 incorporates two second-order Σ-? ADCs， a digital integrator （on CH1）， reference circuitry， temperature sensor， and all the signal processing required to perform active power and energy measurement. An on-chip digital integrator allows direct interface to di/dt current sensors such as a Rogowski coil. The digital integrator eliminates the need for an external analog integrator and provides excellent long-term stability and precise phase matching between the current and the voltage channels. The integrator can be switched off if the ADE7759 is used with conventional current sensors. The ADE7759 contains a sampled waveform register and an active energy register capable of holding at least 11.53 seconds of accumulated power at full ac load. Data is read from the ADE7759 via the serial interface. The ADE7759 also provides a pulse output （CF） with frequency that is proportional to the active power. In addition to active power information， the ADE7759 also provides various system calibration features， i.e.， channel offset correction， phase calibration， and power offset correction. The part also incorporates a detection circuit for short duration voltage drop （SAG）。 The voltage threshold and the duration （in number of half-line cycles） of the drop are user programmable. An open-drain logic output （SAG） goes active low when a sag event occurs. A zero crossing output （ZX） produces an output that is synchronized to the zero crossing point of the line voltage. This output can be used to extract timing or frequency information from the line. The signal is also used internally to the chip in the line cycle energy accumulation mode; i.e.， the number of half-line cycles in which the energy accumulation occurs can be controlled. Line cycle energy accumulation enables a faster and more precise energy accumulation and is especially useful during calibration. This signal is also useful for synchronization of relay switching with a voltage zero crossing. The interrupt request output is an open drain， active low logic output. The interrupt status register indicates the nature of the interrupt， and the interrupt enable register controls which event produces an output on the IRQ pin. The ADE7759 is available in a 20-lead SSOP package.