ADE7753ARS Analog Devices Inc, ADE7753ARS Datasheet - Page 32

• Manufacturer Part Number: ADE7753ARS
• Description: IC ENERGY METERING DETEC 20-SSOP
• Manufacturer: Analog Devices Inc

Specifications of ADE7753ARS

• Rohs Status: RoHS non-compliant
• Input Impedance: 390 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 3mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 20-SSOP (0.200", 5.30mm Width)
• Meter Type: Single Phase
• For Use With: EVAL-ADE7753ZEB - BOARD EVALUATION AD7753

ADE7753
LINE CYCLE ENERGY ACCUMULATION MODE
In line cycle energy accumulation mode, the energy accumula-
tion of the ADE7753 can be synchronized to the Channel 2 zero
crossing so that active energy can be accumulated over an
integral number of half line cycles. The advantage of summing
the active energy over an integer number of line cycles is that
the sinusoidal component in the active energy is reduced to 0.
This eliminates any ripple in the energy calculation. Energy is
calculated more accurately and in a shorter time because the
integration period can be shortened. By using the line cycle
energy accumulation mode, the energy calibration can be
greatly simplified, and the time required to calibrate the meter
can be significantly reduced. The ADE7753 is placed in line
cycle energy accumulation mode by setting Bit 7 (CYCMODE)
in the mode register. In line cycle energy accumulation mode,
the ADE7753 accumulates the active power signal in the
LAENERGY register (Address 0x04) for an integral number of
line cycles, as shown in Figure 69. The number of half line
cycles is specified in the LINECYC register (Address 0x1C). The
ADE7753 can accumulate active power for up to 65,535 half
line cycles. Because the active power is integrated on an integral
number of line cycles, at the end of a line cycle energy accumu-
lation cycle the CYCEND flag in the interrupt status register is
set (Bit 2). If the CYCEND enable bit in the interrupt enable
register is enabled, the IRQ output also goes active low. Thus the
IRQ line can also be used to signal the completion of the line
cycle energy accumulation. Another calibration cycle can start
as long as the CYCMODE bit in the mode register is set.
From Equations 13 and 18,
where:
n is an integer.
T is the line cycle period.
Since the sinusoidal component is integrated over an integer
number of line cycles, its value is always 0. Therefore,
E(t) =
E =
E(t) = VInT
nT
∫
0
VIdt
nT
∫
0
VI
dt
+ 0
−
⎧
⎪
⎪ ⎪
⎨
⎪
⎪
⎪
⎩
1
+
VI
⎛
⎜
⎝
8
f
9 .
⎞
⎟
⎠
2
⎫
⎪
⎪ ⎪
⎬
⎪
⎪
⎪
⎭
nT
∫
0
cos
(2 π ft)dt
Rev. A | Page 32 of 60
(20)
(21)
(22)
Note that in this mode, the 16-bit LINECYC register can hold a
maximum value of 65,535. In other words, the line energy
accumulation mode can be used to accumulate active energy for
a maximum duration over 65,535 half line cycles. At 60 Hz line
frequency, it translates to a total duration of 65,535/120 Hz =
546 seconds.
POSITIVE-ONLY ACCUMULATION MODE
In positive-only accumulation mode, the energy accumulation
is done only for positive power, ignoring any occurrence of
negative power above or below the no-load threshold, as shown
in Figure 70. The CF pulse also reflects this accumulation
method when in this mode. The ADE7753 is placed in positive-
only accumulation mode by setting the MSB of the mode
register (MODE[15]). The default setting for this mode is off.
Transitions in the direction of power flow, going from negative
to positive or positive to negative, set the IRQ pin to active low
if the interrupt enable register is enabled. The interrupt status
registers, PPOS and PNEG, show which transition has
occurred—see the ADE7753 register descriptions in Table 10.
NO-LOAD THRESHOLD
The ADE7753 includes a no-load threshold feature on the active
energy that eliminates any creep effects in the meter. The
ADE7753 accomplishes this by not accumulating energy if the
multiplier output is below the no-load threshold. This threshold
is 0.001% of the full-scale output frequency of the multiplier.
Compare this value to the IEC1036 specification, which states
that the meter must start up with a load equal to or less than
0.4% Ib. This standard translates to .0167% of the full-scale
output frequency of the multiplier.
Figure 70. Energy Accumulation in Positive-Only Accumulation Mode
A CTIVE ENERG Y
ACTIVE POWER
THRESHOLD
THRESHOLD
NO-LOAD
NO-LOAD
IRQ
PPOS
INTERRUPT STATUS REGISTERS
PNEG
PPOS
PNEG
PPOS
PNEG
02875-0-069