The JWE1280 features proprietary ADCs and DSP for high accuracy over large variations in environmental conditions and time. The JWE1280 incorporates two second-order 16-bit Ó-Δ ADCs, a digital integrator (on CH1), reference circuitry, temperature sensor, and all the signal processing required to perform active, reactive, and apparent energy measurements,line-voltage period measurement, and rms calculation on the voltage and current. The selectable on-chip digital integrator provides direct interface to di/dt current sensors such as Rogowski coils, eliminating the need for an external analog integrator and resulting in excellent long-term stability and pre- cise phase matching between the current and voltage channels.
The JWE1280 provides a serial interface to read data, and a pulse output frequency (CF), which is proportional to the active power. Various system calibration features, i.e., channel offset correction, phase calibration, and power calibration, ensure high accuracy. The part also detects short duration low or high voltage variations.
The positive-only accumulation mode gives the option to accumulate energy only when positive power is detected. An internal no-load threshold ensures that the part does not exhibit any creep when there is no load. The zero-crossing output (ZX) produces a pulse that is synchronized to the zero-crossing point of the line voltage. This signal is used internally in the line cycle active and apparent energy accumulation modes,which enables faster calibration.
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, an open-drain, active low logic output.
The JWE1280 is available in a 28-lead SSOP package