ADE7753ARSZ Analog Devices Inc, ADE7753ARSZ Datasheet - Page 42

• Manufacturer Part Number: ADE7753ARSZ
• Description: IC ENERGY METERING 1PHASE 20SSOP
• Manufacturer: Analog Devices Inc

Specifications of ADE7753ARSZ

• 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
• Ic Function: Single-Phase Multifunction Metering IC
• Supply Voltage Range: 4.75V To 5.25V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: SSOP
• No. Of Pins: 20
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-ADE7753ZEB - BOARD EVALUATION AD7753
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

ADE7753
Calibrating Watt Offset with an Accurate Source Example
Figure 83 is the flowchart for watt offset calibration with an
accurate source.
For this example:
Meter Constant:
Line Voltage:
Line Frequency:
CF Numerator:
CF Denominator:
Base Current:
Half Line Cycles Used at Base Current:
Period Register Reading:
Clock Frequency:
Expected LAENERGY Register Value at Base Current
(from the Watt Gain section):LAENERGY
Minimum Current:
Number of Half Line Cycles used at Minimum Current:
Active energy Reading at Minimum Current:
Figure 83. Calibrating Watt Offset with an Accurate Source
SET HALF LINE CYCLES FOR ACCUMULATION
ENABLE LINE CYCLE ACCUMULATION
CALCULATE APOS. SEE EQUATION 49.
ACCUMULATION ADDR. 0x09 = 0x0080
READ LINE ACCUMULATION ENERGY
SET I
WRITE APOS VALUE TO THE APOS
IN LINECYC REGISTER ADDR. 0x1C
RESET THE INTERRUPT STATUS
RESET THE INTERRUPT STATUS
INTERRUPT ADDR. 0x0A = 0x04
READ REGISTER ADDR. 0x0C
READ REGISTER ADDR. 0x0C
SET MODE FOR LINE CYCLE
TEST
REGISTER: ADDR. 0x11
= I
INTERRUPT?
INTERRUPT?
MIN
YES
YES
ADDR. 0x04
MeterConstant(imp/Wh) = 3.2
V
f
CFNUM = 0
CFDEN = 489
I
LINECYC
PERIOD = 8959
CLKIN = 3.579545 MHz
I
LINECYC
LAENERGY
l
b
MIN
, V
nominal
= 50 Hz
= 10 A
TEST
= 40 mA
= V
= 220 V
NOM
(IB)
(IMIN)
NO
NO
, PF = 1
IMIN(nominal)
= 2000
IB(expected)
02875-A-009
= 35700
= 19186
= 1395
Rev. A | Page 42 of 60
The LAENERGY
where:
LAENERGY
from the watt gain calibration.
LINECYC
accumulated over when measuring at I
More line cycles could be required at the minimum current to
minimize the effect of quantization error on the offset calibration.
For example, if a test current of 40 mA results in an active energy
accumulation of 113 after 2000 half line cycles, one LSB variation
in this reading represents an 0.8% error. This measurement does
not provide enough resolution to calibrate out a <1% offset
error. However, if the active energy is accumulated over 37,500
half line cycles, one LSB variation results in 0.05% error, reducing
the quantization error.
APOS is −672 using Equations 55 and 49.
LAENERGY
LAENERGY
INT
LAENERGY
INT
LAENERGY Absolute Error =
LAENERGY Absolute Error = 1395 − 1370 = 25
AENERGY Error Rate (LSB/s) =
AENERGY Error Rate (LSB/s) =
APOS = −
APOS = −
35700
LAENERGY
25
⎛
⎜
⎜
⎝
⎛
⎜
⎝
IMIN
. 0
I
2 /
10
IB(expected)
MIN
I
04
LINECYC
B
is the number of half line cycles that energy is
×
. 0
AENERGY
×
. 3
×
IMIN(nominal)
IMIN(expected)
IMIN(expected)
expected
. 3
19186
069948771
579545
Absolute
LAENERGY
579545
is the expected LAENERGY reading at I
8
×
8959
at I
2 /
×
35700
×
CLKIN
MIN
2000
×
=
=
− LAENERGY
10
Error
Error
10
×
6
is 1370 using Equation 53.
2
IB
6
35
=
(
⎞
⎟
⎠
expected
. 0
Rate
=
×
=
069948771
INT
8
−
×
672
CLKIN
×
PERIOD
MIN
)
(
2
1369
×
IMIN(expected)
35
.
LINECYCI
LINECYC
.
80
)
=
1370
MIN
IB
⎞
⎟
⎟
⎠
b
(53)
(54)
(55)