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## ADE7755 Datasheet(HTML) 13 Page - Analog Devices

 13 / 20 page ADE7755Rev. A | Page 13 of 20NONSINUSOIDAL VOLTAGE AND CURRENTThe active power calculation method also holds true for non-sinusoidal current and voltage waveforms. All voltage and currentwaveforms in practical applications have some harmonic content.Using the Fourier Transform operation, instantaneous voltageand current waveforms can be expressed in terms of theirharmonic content.(∑∞≠+××+=0tsin2)(hhhOahωVVtv)(1)where:v(t)is the instantaneous voltage.VOis the average voltage value.Vhis the rms value of the voltage harmonic, h.ahis the phase angle of the voltage harmonic.∑∞≠+××+=0)tsin(2)(hhhOβhωIIti(2)where:i(t) is the instantaneous current.IO is the current dc component.Ih is the rms value of the current harmonic, h.βh is the phase angle of the current harmonic.Using Equation 1 and Equation 2, the active power (P) can beexpressed in terms of its fundamental active power (P1) andharmonic active power (PH).P = P1 + PH(3)where:P1 is the active power of the fundamental component:P1 = V1 × I1 cosΦ1Φ1 = α1 – β1andPH is the active power of all harmonic components:∑∞≠Φ×=1coshhhhHIVPΦh = αh – βhA harmonic active power component is generated for everyharmonic, provided that the harmonic is present in both thevoltage and current waveforms. The power factor calculationpreviously shown is accurate in the case of a pure sinusoid;therefore, the harmonic active power must also correctlyaccount for the power factor because it is made up of a series ofpure sinusoids.Note that the input bandwidth of the analog inputs is 14 kHzwith a master clock frequency of 3.5795 MHz.ANALOG INPUTSChannel 1 (Current Channel)The voltage output from the current transducer is connectedto the ADE7755 at Channel 1. Channel 1 is a fully differentialvoltage input. V1P is the positive input with respect to V1N.The maximum peak differential signal on Channel 1 should beless than ±470 mV (330 mV rms for a pure sinusoidal signal)for specified operation. Note that Channel 1 has a programmablegain amplifier (PGA) with user-selectable gain of 1, 2, 8, or 16(see Table 5). These gains facilitate easy transducer interfacing.+470mV–470mVVCMV1DIFFERENTIAL INPUT±470mV MAX PEAKCOMMON-MODE±100mV MAXV1PV1NV1VCMAGNDFigure 24. Maximum Signal Levels, Channel 1, Gain = 1Figure 24 illustrates the maximum signal levels on V1P andV1N. The maximum differential voltage is ±470 mV divided bythe gain selection. The differential voltage signal on the inputsmust be referenced to a common mode, for example, AGND.The maximum common-mode signal is ±100 mV, as shown inFigure 24.Table 5. Gain Selection for Channel 1G1G0GainMaximum Differential Signal (mV)001±470012±235108±601116±30