ADE7753ARSZ Analog Devices Inc, ADE7753ARSZ Datasheet - Page 38

• 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
Watt Gain
The first step of calibrating the gain is to define the line voltage,
base current and the maximum current for the meter. A meter
constant needs to be determined for CF, such as 3200 imp/kWh
or 3.2 imp/Wh. Note that the line voltage and the maximum
current scale to half of their respective analog input ranges in
this example.
The expected CF in Hz is
where
factor.
The ratio of active energy LSBs per CF pulse is adjusted using
the CFNUM, CFDEN, and WDIV registers.
The relationship between watt-hours accumulated and the
quantity read from AENERGY can be determined from the
amount of active energy accumulated over time with a given
load:
where Accumulation Time can be determined from the value in
the line period and the number of half line cycles fixed in the
LINECYC register.
The line period can be determined from the PERIOD register:
The AENERGY Wh/LSB ratio can also be expressed in terms of
the meter constant:
In a meter design, WDIV, CFNUM, and CFDEN should be kept
constant across all meters to ensure that the Wh/LSB constant is
maintained. Leaving WDIV at its default value of 0 ensures
maximum resolution. The WDIV register is not included in the
CF signal chain so it does not affect the frequency pulse output.
CF
CF
Accumulation time(s) =
Line Period(s) = PERIOD ×
Wh
Wh
MeterConst
ϕ
expected
expected
is the angle between I and V, and cos
LSB
LSB
(Hz) =
=
=
=
Accumulati
MeterConst
Load
ant
(
(
CFNUM
CFDEN
3600
LAENERGY
(imp/Wh)
LAENERGY
(W)
s/h
×
onTime
+
+
Accumulati
ant
) 1
) 1
LINECYC
× Load
(imp/Wh)
×
WDIV
CLKIN
(s)
×
3600
×
8
(W)
WDIV
on
IB
s/
Time
×
×
h
2
cos(
Line
×
(
(
(ϕ
CFNUM
(s)
CFDEN
ϕ
)
Period
)
is the power
+
+
(s)
) 1
) 1
(34)
(35)
(36)
(37)
(38)
(39)
Rev. A | Page 38 of 60
The WGAIN register is used to finely calibrate each meter. Cali-
brating the WGAIN register changes both CF and AENERGY for
a given load condition.
When calibrating with a reference meter, WGAIN is adjusted
until CF matches the reference meter pulse output. If an accurate
source is used to calibrate, WGAIN is modified until the active
energy accumulation rate yields the expected CF pulse rate.
The steps of designing and calibrating the active energy portion
of a meter with either a reference meter or an accurate source
are outlined in the following examples. The specifications for
this example are
Meter Constant:
Base Current:
Maximum Current:
Line Voltage:
Line Frequency:
The first step in calibration with either a reference meter or an
accurate source is to calculate the CF denominator, CFDEN.
This is done by comparing the expected CF pulse output to the
nominal CF output with the default CFDEN = 0x3F and
CFNUM = 0x3F and when the base current is applied.
The expected CF output for this meter with the base current
applied is 1.9556 Hz using Equation 34.
Alternatively, CF
pulse output if available.
The maximum CF frequency measured without any frequency
division and with ac inputs at full scale is 23 kHz. For this
example, the nominal CF with the test current, I
958 Hz. In this example the line voltage and maximum current
scale half of their respective analog input ranges. The line
voltage and maximum current should not be fixed at the
maximum analog inputs to account for occurrences such as
spikes on the line.
AENERGY
CF
CF
CF
CF
CF
. 3
200
expected
IB(expected)
expected
nominal
IB(nominal)
imp/Wh
(Hz) =
(Hz) = CF
(Hz) = CF
(Hz) =
3600
(Hz) =
expected
expected
×
s/h
10
23
= AENERGY
can be measured from a reference meter
23
ref
A
nominal
kHz
×
kHz
220
×
MeterConstant(imp/Wh) = 3.2
I
I
V
f = 50 Hz
×
l
b
MAX
1
×
V
nominal
= 10 A
2
(
1
(
CFNUM
CFDEN
×
×
2
= 60 A
nominal
cos(
×
1
= 220 V
2
1
×
2
ϕ
×
×
)
I
⎛
⎜ ⎜
⎝
+
MAX
+
10
=
1
I
) 1
) 1
. 1
+
60
9556
WGAIN
×
⎛
⎜ ⎜
⎝
=
2
1
12
b
+
958
, applied is
Hz
WGAIN
2
⎞
⎟ ⎟
⎠
Hz
12
⎞
⎟ ⎟
⎠
(40)
(41)
(42)
(43)