ADE7758ARW Analog Devices Inc, ADE7758ARW Datasheet - Page 41

• Manufacturer Part Number: ADE7758ARW
• Description: IC ENERGY METERING 24-SOIC
• Manufacturer: Analog Devices Inc

Specifications of ADE7758ARW

• Rohs Status: RoHS non-compliant
• Input Impedance: 380 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 8mA
• 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: Not Compliant

Table 14. Inputs to VA-Hr Accumulation Registers
CONSEL[1, 0]
00
01
10
11
1
Energy Accumulation Mode
The apparent power accumulated in each VA-hr accumulation
register (AVAHR, BVAHR, or CVAHR) depends on the con-
figuration of the CONSEL bits in the COMPMODE register
(Bit 0 and Bit 1). The different configurations are described in
Table 14.
The contents of the VA-hr accumulation registers are affected
by both the registers for the current gain (IGAIN) and rms
voltage gain (VRMSGAIN), as well as the VAGAIN register of
the corresponding phase. IGAIN should not be used when
using CONSEL Mode 0, COMPMODE[1:0].
Apparent Power Frequency Output
Pin 17 (VARCF) of the ADE7758 provides frequency output for
the total apparent power. By setting the VACF bit (Bit 7) of the
WAVMODE register, this pin provides an output frequency that
is directly proportional to the total apparent power.
A digital-to-frequency converter (DFC) is used to generate the
pulse output from the total apparent power. The TERMSEL bits
(Bit 2 to Bit 4) of the COMPMODE register can be used to
select which phases to include in the total power calculation.
Setting Bit 2, Bit 3, and Bit 4 includes the input to the AVAHR,
BVAHR, and CVAHR registers in the total apparent power
calculation. A pair of frequency divider registers, namely
VARCFDEN and VARCFNUM, can be used to scale the output
frequency of this pin. Note that either VAR or apparent power
can be selected at one time for this frequency output (see the
Reactive Power Frequency Output section).
Line Cycle Apparent Energy Accumulation Mode
The line cycle apparent energy accumulation mode is activated
by setting the LVA bit (Bit 2) in the LCYCMODE register. The
total apparent energy accumulated over an integer number of
zero crossings is written to the VA-hr accumulation registers
after the LINECYC number of zero crossings is detected. The
operation of this mode is similar to watt-hr accumulation (see
the Line Cycle Active Energy Accumulation Mode section).
When using the line cycle accumulation mode, the RSTREAD
bit (Bit 6) of the LCYCMODE register should be set to Logic 0.
Note that this mode is especially useful when the user chooses
to perform the apparent energy calculation using the vectorial
method.
AVRMS/BVRMS/CVRMS are the rms voltage waveform, and AIRMS/BIRMS/CIRMS are the rms values of the current waveform.
AVAHR
AVRMS × AIRMS
AVRMS × AIRMS
AVRMS × AIRMS
Reserved
1
BVAHR
BVRMS × BIRMS
AVRMS + CVRMS/2 × BIRMS
BVRMS × BIRMS
Reserved
Rev. D | Page 41 of 72
By setting LWATT and LVAR bits (Bit 0 and Bit 1) of the
LCYCMODE register, the active and reactive energies are
accumulated over the same period. Therefore, the MCU can
perform the squaring of the two terms and then take the square
root of their sum to determine the apparent energy over the
same period.
ENERGY REGISTERS SCALING
The ADE7758 provides measurements of active, reactive, and
apparent energies that use separate signal paths and filtering for
calculation. The differences in the datapaths can result in small
differences in LSB weight between the active, reactive, and
apparent energy registers. These measurements are internally
compensated so that the scaling is nearly one to one. The
relationship between the registers is shown in Table 15.
Table 15. Energy Registers Scaling
Integrator Off
Integrator On
WAVEFORM SAMPLING MODE
The waveform samples of the current and voltage waveform, as
well as the active, reactive, and apparent power multiplier out-
puts, can all be routed to the WAVEFORM register by setting
the WAVSEL[2:0] bits (Bit 2 to Bit 4) in the WAVMODE
register. The phase in which the samples are routed is set by
setting the PHSEL[1:0] bits (Bit 0 and Bit 1) in the WAVMODE
register. All energy calculation remains uninterrupted during
waveform sampling. Four output sample rates can be chosen by
using Bit 5 and Bit 6 of the WAVMODE register (DTRT[1:0]).
The output sample rate can be 26.04 kSPS, 13.02 kSPS,
6.51 kSPS, or 3.25 kSPS (see Table 20).
By setting the WFSM bit in the interrupt mask register to
Logic 1, the interrupt request output IRQ goes active low when
a sample is available. The 24-bit waveform samples are
transferred from the ADE7758 one byte (8 bits) at a time, with
the most significant byte shifted out first.
VAR
VA
VAR
VA
60 Hz
1.004 × WATT
1.00058 × WATT
1.0059 × WATT
1.00058 × WATT
CVAHR
CVRMS × CIRMS
CVRMS × CIRMS
CVRMS × CIRMS
Reserved
Frequency
50 Hz
1.0054 × WATT
1.0085 × WATT
1.0064 × WATT
1.00845 × WATT
ADE7758