ADE7758ARW Analog Devices Inc, ADE7758ARW Datasheet - Page 51

• 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

To set APCFNUM (0x45) and APCFDEN (0x46) to the
calculated value to perform a coarse adjustment on the
imp/kW-hr ratio, use Equation 45 to Equation 47.
Under the test conditions above, the AWATTHR register value
is 15559d after the LENERGY interrupt. Using Equation 60 and
Equation 61, the value to be written to AWG is −199d, 0xF39.
Using Equation 66, the Wh/LSB constant is
Phase Calibration Using Line Accumulation
The ADE7758 includes a phase calibration register on each
phase to compensate for small phase errors. Large phase errors
should be compensated by adjusting the antialiasing filters. The
ADE7758’s phase calibration is a time delay with different weights
in the positive and negative direction (see the Phase Compensation
section). Because a current transformer is a source of phase
error, a fixed nominal value can be decided on to load into the
xPHCAL (0x3F to 0x41) registers at power-up. During
calibration, this value can be adjusted for CT-to-CT error.
Figure 82 shows the steps involved in calibrating the phase
using the line accumulation mode.
AccumTime
WATTHR
xWG
APCF
APCF
APCFDEN
AccumTime
4
Wh
LSB
×
3200
=
NOMINAL
EXPECTED
=
10
=
⎛
⎜
⎝
3600
1000
×
14804
15559
2
×
EXPECTED
10
×
=
220
=
FREQ
×
INT
=
×
×
=
2
220
16
14804
×
3600
−
3200
×
1
. 6
1000
⎛
⎜
⎜
⎝
kH
2085
[
⎞
× ⎟
⎠
=
. 1
11
×
832
541
1
956
2
×
z
:
×
12
] 0
5 .
10
×
0
×
1
×
=
. 6
x
×
=
3600
Hz
9
Hz
220
500
832
0.000282
1
800
×
9
6 .
LINECYC
–198.87640
6 .
220
×
⎞
⎟
⎟
⎠
×
×
10
×
=
10
130
277
×
277
10
−
1
−6
6
cos
0
×
×
=
×
[
3
15
( )
No.
1
. 0
θ
=
=
:
=
5415
0
–199
=
6.832128s
]
14804
of
1.956
Phases
kHz
=
0xF39
Hz
Selected
Rev. D | Page 51 of 72
Step 1: If the values were changed after gain calibration, Step 1,
Step 3, and Step 4 from the gain calibration should be repeated
to configure the LCYCMODE and LINECYC registers.
Step 2: Set the test system for I
inductive.
Step 3: Reset the interrupt status register by reading RSTATUS
(0x1A).
Step 4: The xWATTHR registers should be read after the
LENERGY interrupt. Measure the percent error in the energy
register readings (AWATTHR, BWATTHR, and CWATTHR)
compared to the energy register readings at unity power factor
(after gain calibration) using Equation 69. The readings at unity
power factor should have been repeated after the gain calibration
and stored for use in the phase calibration routine.
Step 5: Calculate the Phase Error in degrees using the equation
Step 6: Calculate xPHCAL and write to the xPHCAL registers
(0x3F to 0x41).
Phase
xPHCAL
Error
Phase
Error
Figure 82. Phase Calibration Using Line Accumulation
=
=
Error
×
xWATTHR
PHCAL
( )
°
=
–
SET UP SYSTEM FOR
I
READ ALL xWATTHR
ERROR IN DEGREES
xPHCAL REGISTERS
_
LINECYC AND MASK
STEP 1
STEP 2
TEST
STEP 3
STEP 4
STEP 5
CALCULATE PHASE
STEP 6
xWATTHR
REGISTERS AFTER
FOR ALL PHASES
Arcsin
CALCULATE AND
SET LCYCMODE,
LSB
RESET STATUS
WRITE TO ALL
PF
1
REGISTERS
INTERRUPT
, V
INDUCTIVE
REGISTER
LENERGY
=
NOM
5
_
–
⎛
⎜
⎝
Weight
2
TEST
, PF = 0.5,
Error
xWATTHR
, V
PF
3
=
NOM
⎞
⎟
⎠
1
×
2
Line
, and 0.5 power factor
PF
Period
=
1
1
ADE7758
(
s
)
×
360
1
°
(69)
(70)
(71)