ade7953 Analog Devices, Inc., ade7953 Datasheet - Page 31

• Manufacturer Part Number: ade7953
• Description: Single Phase, Multifunction Metering Ic With Neutral Current Measurement Ade7953
• Manufacturer: Analog Devices, Inc.

Apparent Energy Line Cycle Accumulation Mode
In apparent energy line cycle accumulation mode, the energy
accumulation of the ADE7953 is synchronized to the voltage
channel zero crossing so that the apparent energy on Current
Channel A and Current Channel B can be accumulated over
an integral number of half line cycles. Line cycle accumulation
mode is disabled by default and can be enabled on Current
Channel A and Current Channel B by setting the ALVA and
BLVA bits to 1 in the LCYCMODE register (Address 0x004).
The accumulation time should be written to the LINECYC
register (Address 0x101) in the unit of number of half line cycles.
The number of half line cycles written to the LINECYC register
is used for both the Current Channel A and Current Channel B
accumulation periods. The ADE7953 can accumulate apparent
energy for up to 65,535 half line cycles. This equates to an accu-
mulation period of approximately 655 sec with 50 Hz inputs
and 546 sec with 60 Hz inputs.
At the end of a line cycle accumulation cycle, the APENERGYA
and APENERGYB registers are updated, and the CYCEND flag
in the IRQSTATA register (Address 0x22D and Address 0x32D)
is set. If the CYCEND bit in the IRQENA register is set, an external
interrupt is issued on the IRQ pin. In this way, the IRQ pin can
also be used to signal the completion of the line cycle accumula-
tion. Another accumulation cycle begins immediately, as long as
the ALVA and BLVA bits in the LCYCMODE register remain set.
The contents of the APENERGYA and APENERGYB registers
are updated synchronous to the CYCEND flag. The APENERGYA
and APENERGYB registers hold their current values until the
end of the next line cycle period, when the contents are replaced
with the new reading. If the read-with-reset bit (RSTREAD) in
the LCYCMODE register (Address 0x004) is set, the contents of
the APENERGYA and APENERGYB registers are cleared after
a read and remain at 0 until the end of the next line cycle period.
VOLTAGE CHANNEL
OUTPUT FROM
APPARENT
POWER
SIGNAL
ADC
LPF1
Figure 56. Apparent Energy Line Cycle Accumulation
xVAGAIN
ZERO-CROSSING
DETECTION
Rev. 0 | Page 31 of 68
+
xVAOS
+
15
48
FIXED INTERNAL
ACCUMULATION
CALIBRATION
If a new value is written to the LINECYC register (Address 0x101)
midway through a line cycle accumulation, the new value is not
internally loaded until the end of a line cycle period. When the
LINECYC register is updated mid-reading, the current energy
accumulation cycle is completed, and the new value is then
programmed, ready for the next cycle. This prevents any invalid
readings due to changes to the LINECYC register (see Figure 47).
Note that when line cycle accumulation mode is first enabled, the
reading after the first CYCEND flag should be ignored because
it may be inaccurate. This is because the line cycle accumulation
mode is not synchronized to the zero crossing and, therefore,
the first reading may not be over a complete number of half line
cycles. After the first line cycle accumulation is complete, all
successive readings will be correct.
AMPERE-HOUR ACCUMULATION
In a tampering situation where no voltage is available to the energy
meter, the ADE7953 can accumulate the ampere-hour measure-
ment instead of the apparent power in the APENERGYA and
APENERGYB registers. If enabled, the Current Channel A and
Current Channel B IRMS measurements are continually accu-
mulated instead of the apparent power. If enabled, the apparent
power CF output pin also reflects the ampere-hour measurement
(see the Energy-to-Frequency Conversion section). All the signal
processing and calibration registers available for the apparent
power and apparent energy accumulation remain active when
the ampere-hour accumulation mode is enabled. This includes
the apparent energy no-load feature (see the Apparent Energy
No-Load section). Recalibration is required in this mode due to
internal scaling differences between the IRMS and apparent
signals.
THRESHOLD
INTERNAL
CONTROL
LINECYC
0
0
23
APENERGYx
0
ADE7953