ADE7752ARZ Analog Devices Inc, ADE7752ARZ Datasheet - Page 12

• Manufacturer Part Number: ADE7752ARZ
• Description: IC ENERGY METERING DETEC 24-SOIC
• Manufacturer: Analog Devices Inc

Specifications of ADE7752ARZ

• Input Impedance: 450 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 6mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SOIC (0.300", 7.50mm Width)
• Meter Type: 3 Phase
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADE7752/ADE7752A
THEORY OF OPERATION
The six voltage signals from the current and voltage transducers
are digitized with ADCs. These ADCs are 16-bit second-order
∑-Δ with an oversampling rate of 833 kHz. This analog input
structure greatly simplifies transducer interface by providing a
wide dynamic range for direct connection to the transducer and
also by simplifying the antialiasing filter design. A high-pass
filter in the current channel removes the dc component from
the current signal. This eliminates any inaccuracies in the real
power calculation due to offsets in the voltage or current
signals. See the
The real power calculation is derived from the instantaneous
power signal. The instantaneous power signal is generated by a
direct multiplication of the current and voltage signals of each
phase. In order to extract the real power component (the dc
component), the instantaneous power signal is low-pass filtered
on each phase.
power signal and shows how the real power information can be
extracted by low-pass filtering the instantaneous power signal.
This method is used to extract the real power information on
each phase of the polyphase system. The total real power
information is then obtained by adding the individual phase
real power. This scheme correctly calculates real power for
nonsinusoidal current and voltage waveforms at all power
factors. All signal processing is carried out in the digital domain
for superior stability over temperature and time.
Figure 15 illustrates the instantaneous real
HPF and Offset Effects section.
VBP
VCP
VAP
V × I
V × I
IAN
IBN
ICN
IAP
IBP
ICP
VN
2
TIME
ADC
ADC
ADC
ADC
ADC
ADC
p(t) = i(t) × v(t)
WHERE:
POWER SIGNAL - p(t)
v(t) = V × cos (ωt)
i(t) = I × cos (ωt)
p(t) =
INSTANTANEOUS
MULTIPLIER
MULTIPLIER
MULTIPLIER
V × I
2
HPF
HPF
HPF
{1+ cos (2ωt)}
Figure 15. Signal Processing Block Diagram
LPF
LPF
LPF
Rev. C | Page 12 of 24
V × I
2
ABS
REAL POWER SIGNAL
|X|
|X|
|X|
INSTANTANEOUS
The low frequency output of the ADE7752 is generated by
accumulating the total real power information. This low
frequency inherently means a long accumulation time between
output pulses. The output frequency is therefore proportional to
the average real power. This average real power information
can, in turn, be accumulated (by a counter, for example) to
generate real energy information. Because of its high output
frequency and therefore shorter integration time, the CF output
is proportional to the instantaneous real power. This pulse is
useful for system calibration purposes that would take place
under steady load conditions.
POWER FACTOR CONSIDERATIONS
Low-pass filtering, the method used to extract the real power
information from the individual instantaneous power signal, is
still valid when the voltage and current signals of each phase are
not in phase.
condition and a DPF (displacement power factor) = 0.5, or
current signal lagging the voltage by 60°, for one phase of the
polyphase. Assuming that the voltage and current waveforms
are sinusoidal, the real power component of the instantaneous
power signal, or the dc term, is given by
Σ
⎛
⎜
⎝
V
2
×
1
VA × IA + VB × IB +
⎞
⎟
⎠
×
Figure 16 displays the unity power factor
cos
Σ
Σ
INSTANTANEOUS
VC×IC
POWER SIGNAL
FREQUENCY
FREQUENCY
2
DIGITAL-TO-
DIGITAL-TO-
(
60
TOTAL
°
)
CF
F1
F2