ADE7878ACPZ Analog Devices Inc, ADE7878ACPZ Datasheet - Page 42

• Manufacturer Part Number: ADE7878ACPZ
• Description: IC ENERGY METERING 3PH 40LFCSP
• Manufacturer: Analog Devices Inc

Specifications of ADE7878ACPZ

• Input Impedance: 400 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.4V
• Current - Supply: 22mA
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 40-WFQFN, CSP Exposed Pad
• Meter Type: 3 Phase
• Supply Voltage Range: 3V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: LFCSP
• No. Of Pins: 40
• Msl: MSL 1 - Unlimited
• Peak Reflow Compatible (260 C): Yes
• Supply Voltage Min: 3V
• Rohs Compliant: Yes
• Leaded Process Compatible: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADE7878
If the phase currents and voltages contain only the fundamental
component, are in phase (that is φ
full-scale ADC inputs, then multiplying them results in an
instantaneous power signal that has a dc component, V
and a sinusoidal component, V
the corresponding waveforms.
Because LPF2 does not have an ideal brick wall frequency
response (see Figure 60), the active power signal has some
ripple due to the instantaneous power signal. This ripple is
sinusoidal and has a frequency equal to twice the line
frequency. Because the ripple is sinusoidal in nature, it is
removed when the active power signal is integrated over
time to calculate the energy.
0x1FF6A6B =
Vrms × Irms
0x3FED4D6
0x000 0000
67,032,278
33,516,139
INSTANTANEOUS
POWER SIGNAL
i(t) = √2 × Irms × sin(ωt)
v(t) = √2 × Vrms × sin(ωt)
Figure 59. Active Power Calculation
VA
IA
APHCAL
p(t)= Vrms × Irms – Vrms × Irms × cos(2ωt)
1
× I
1
AVGAIN
AIGAIN
1
= γ
cos(2ωt). Figure 59 shows
1
= 0) and correspond to
HPFDIS
HPFDIS
[23:0]
[23:0]
HPF
HPF
INSTANTANEOUS
ACTIVE POWER
SIGNAL: Vrms × Irms
Figure 58. Total Active Power Datapath
1
INTEGRATOR
× I
DIGITAL
1
,
Rev. 0 | Page 42 of 92
DIGITAL SIGNAL PROCESSOR
LPF
The ADE7878 stores the instantaneous total phase active
powers into the AWATT[23:0], BWATT[23:0], and
CWATT[23:0] registers. Their expression is
where:
U
the ADC inputs are at full scale.
PMAX = 33,516,139; it is the instantaneous power computed
when the ADC inputs are at full scale and in phase.
The xWATT[23:0] waveform registers can be accessed using
various serial ports. Refer to the Waveform Sampling Mode
section for more details.
FS
, I
FS
xWATT
AWATTOS
–10
–15
–20
–25
–5
are the rms values of the phase voltage and current when
0
0.1
Figure 60. Frequency Response of the LPF Used
to Filter Instantaneous Power in Each Phase
=
∑
k
AWGAIN
∞
=
1
U
U
FS
k
×
I
INSTANTANEOUS
PHASE A ACTIVE
I
FS
FREQUENCY (Hz)
k
×
POWER
cos(φ
1
k
– γ
k
) × PMAX ×
3
2
1
10
4
(20)