ADE7763ARS Analog Devices Inc, ADE7763ARS Datasheet - Page 41

• Manufacturer Part Number: ADE7763ARS
• Description: IC ENERGY METER 1PHASE 20SSOP
• Manufacturer: Analog Devices Inc

Specifications of ADE7763ARS

• 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-ADE7763ZEB - BOARD EVALUATION FOR ADE7763
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Calibrating Phase with an Accurate Source Example
With an accurate source, line cycle accumulation is a good
method of calibrating phase error. The value of LAENERGY
must be obtained at two power factors, PF = 1 and PF = 0.5
inductive.
For this example:
Meter Constant:
Line Voltage:
Line Frequency:
CF Numerator:
CF Denominator:
Base Current:
Half Line Cycles Used at Base Current:
PERIOD Register:
Expected Line Accumulation at Unity Power Factor (from Watt
Gain section):
Active Energy Reading at PF = 0.5 inductive:
Figure 76. Calibrating Phase with an Accurate Source
SET HALF LINE CYCLES FOR ACCUMULATION
CALCULATE PHCAL. SEE EQUATION 55.
ENABLE LINE CYCLE ACCUMULATION
ACCUMULATION ADDR. 0x09 = 0x0080
READ LINE ACCUMULATION ENERGY
WRITE PHCAL VALUE TO THE PHCAL
SET I
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. 0x10
= I
INTERRUPT?
INTERRUPT?
b
ADDR. 0x04
YES
YES
, V
TEST
MeterConstant (imp/Wh) = 3.2
V
f
CFNUM = 0
CFDEN = 489
I
LINECYC
PERIOD = 8959
LAENERGY
LAENERGY
L
b
nominal
= 50 Hz
= 10 A
= V
NOM
= 220 V
, PF = 0.5
IB
NO
NO
= 2000
IB(expected)
IB, PF = 0.5
= 9613
= 19186
Rev. B | Page 41 of 56
The error using Equation 52 is
Using Equation 55, PHCAL is 11.
Note that PHCAL is a signed, twos complement register.
The phase lead is corrected by 0.08 degrees when the PHCAL
register is set to 11:
VRMS and IRMS Calibration
VRMS and IRMS are calculated by squaring the input in a
digital multiplier.
The square of the rms value is extracted from v
filter. The square root of the output of this low-pass filter gives
the rms value. An offset correction is provided to cancel noise
and offset contributions from the input.
There is ripple noise from the 2ω term because the low-pass
filter does not completely attenuate the signal. This noise can be
minimized by synchronizing the rms register readings with the
zero crossing of the voltage signal. The IRQ output can be
configured to indicate the zero crossing of the voltage signal.
This flowchart demonstrates how VRMS and IRMS readings
are synchronized to the zero crossings of the voltage input.
Error =
Phase Error (°) = −Arcsin
PHCAL = INT
Phase Correction (°) = −
Phase Correction (°) = −
v
2
) (
t
=
9613
2
V
19186
sin(
−
⎛
⎜
⎝
19186
−
ω
. 0
t
2
)
07
×
2
°
×
2
(
(
=
11
PHCAL
V
8959
360
⎛
⎜ ⎜
⎝
. 0
. 0
sin(
−
0021
0021
°
0x0D
3
⎞
⎟
⎠
ω
+
t
−
)
⎞
⎟ ⎟
⎠
0x0D
)
=
0x0D
=
×
V
−
8960
360
2
. 0
=
−
)
07
×
°
2
−
V
( t ) by a low-pass
°
2
=
PERIOD
2
ADE7763
+
. 0
×
360
13
08
cos(
°
°
=
2
11
ω
t
(59)
)