ADE7754AR Analog Devices Inc, ADE7754AR Datasheet - Page 22

• Manufacturer Part Number: ADE7754AR
• Description: IC ENERY METER 3PHASE 24-SOIC
• Manufacturer: Analog Devices Inc

Specifications of ADE7754AR

• Input Impedance: 370 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 7mA
• 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
• For Use With: EVAL-ADE7754EBZ - BOARD EVALAUTION FOR ADE7754
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: AD71049AR; AD71049AR

ADE7754
by setting to Logic 1 Bit 3 of the gain register (Address 18h). See
Table X. Any load generating an active power amplitude lower
than the minimum amplitude specified will not be taken into
account when accumulating the active power from this phase.
The minimum instantaneous active power allowed in this mode
is 0.005% of the full-scale amplitude. Because the maximum
active power value is 13,743,895d with full-scale analog input,
the no-load threshold is 687d. For example, an energy meter
with maximum inputs of 220 V and 40 A and Ib = 10 A, the
maximum instantaneous active power is 3,435,974d, assuming
that both inputs represent half of the analog input full scale. As
the no-load threshold represents 687d, the start-up current
represents 8 mA or 0.08% of Ib.
Mode Selection of the Sum of the Three Active Energies
The ADE7754 can be configured to execute the arithmetic sum
of the three active energies, Wh = Wh
sum of the absolute value of these energies, Wh = |Wh
|Wh
be made by setting Bit 2 of the gain register (Address 18h). See
Table X. Logic high and logic low of this bit correspond to the
sum of absolute values and the arithmetic sum, respectively.
This selection affects the active energy accumulation in the
AENERGY, RAENERGY, and LAENERGY registers as well
as the CF frequency output.
When the sum of the absolute values is selected, the active
energy from each phase is always counted positive in the total
active energy. It is particularly useful in a 3-phase, 4-wire instal-
lation where the sign of the active power should always be the
same. If the meter is misconnected to the power lines (e.g., CT
is connected in the wrong direction), the total active energy
recorded without this solution can be reduced by two thirds. The
sum of the absolute values ensures that the active energy recorded
represents the actual active energy delivered. In this mode, the
reverse power information available in the CFNUM register is
still detecting when negative active power is present on any of
the three phase inputs.
FROM VA
ADC
FROM VB
ADC
FROM VC
ADC
B
| + |Wh
LPF1
LPF1
LPF1
C
|. The selection between the two modes can
ZERO-CROSS
ZERO-CROSS
ZERO-CROSS
DETECT
DETECT
DETECT
REGISTER BIT 4
REGISTER BIT 5
REGISTER BIT 6
MMODE
MMODE
MMODE
A
+ Wh
Figure 31. Active Energy Calibration
B
+ Wh
C
A
, or the
| +
CALIBRATION
LINCYC[15:0]
ACCUMULATE ACTIVE POWER
DURING LINCYC ZERO CROSSINGS
CONTROL
–22–
LINE ENERGY ACCUMULATION
The ADE7754 is designed with a special energy accumulation
mode that simplifies the calibration process. By using the on-
chip zero-crossing detection, the ADE7754 accumulates the
active power signal in the LAENERGY register for an integer
number of half cycles, as shown in Figure 31. The line active
energy accumulation mode is always active.
Using this mode with only one phase selected is recommended.
If several phases are selected, the amount accumulated may be
smaller than it should be.
Each one of three phases zero-crossing detection can contribute
to the accumulation of the half line cycles. Phase A, B, and C
zero crossings, respectively, are taken into account when count-
ing the number of half line cycles by setting Bits 4 to 6 of the
MMODE register to Logic 1. Selecting phases for the zero-
crossing counting also has the effect of enabling the zero-cross-
ing detection, zero-crossing timeout and period measurement
for the corresponding phase as described in the zero-crossing
detection paragraph.
The number of half line cycles is specified in the LINCYC
register. LINCYC is an unsigned 16-bit register. The ADE7754
can accumulate active power for up to 65535 combined half
cycles. Because the active power is integrated on an integer
number of line cycles, the sinusoidal component is reduced to
zero. This eliminates any ripple in the energy calculation. Energy
is calculated more accurately because of this precise timing
control. At the end of an energy calibration cycle, the LINCYC
flag in the interrupt status register is set. If the LINCYC enable
bit in the interrupt enable register is set to Logic 1, the IRQ
output also goes active low.
POWER
PHASE B
POWER
PHASE A
POWER
PHASE C
+
+
+
+
WDIV
51
51
23
AENERGY[23:0]
%
0
REV. 0
0
0