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Evaluation Board Documentation
ADE7753 Energy Metering IC
EVAL-ADE7753EB
FEATURES
Evaluation board is designed to be used together with
accompanying software to implement a fully functional
energy meter (watt-hour meter)
Easy connection of various external transducers via screw
terminals
Easy modification of signal conditioning components using
PCB sockets
LED indicators on logic outputs CF, ZX, SAG, and IRQ
Optically isolated data output connection to PC parallel port
Optically isolated frequency output (CF) to BNC
External reference option available for on-chip reference
evaluation
GENERAL DESCRIPTION
The evaluation board was designed so that the ADE7753 can be
evaluated in the end application, i.e., watt-hour meter. Using the
appropriate transducers on the current channel, e.g., di/dt
sensor, CT, and shunt, the evaluation board can be connected to
a test bench or high voltage (240 V rms) test circuit. An on-
board resistor divider network provides the attenuation for the
line voltage. This data sheet also describes how the current
transducers should be connected for the best performance. The
ADE7753 has a built-in digital integrator that allows for simple
interfacing with any di/dt sensor (such as the Rogowski coil).
The evaluation board (watt-hour meter) is configured and
calibrated via the parallel port of a PC. The data interface
between the evaluation board and the PC is fully isolated.
Windows® based software is provided with the evaluation board
so it can be configured quickly as an energy meter.
The ADE7753 is a high accuracy electrical power measurement
IC with a serial interface and pulse output. The ADE7753
incorporates two second-order Σ-Δ ADCs, reference circuitry,
temperature sensor, and all the signal processing required to
perform active, reactive, and apparent energy measurement.
The evaluation board also functions as a standalone evaluation
system, which can be incorporated easily into an existing system
via a 25-way D-Sub connector.
The evaluation board requires two external 5 V power supplies
(one is required for isolation purposes) and the appropriate
current transducer.
This data sheet describes the ADE7753 evaluation kit’s
hardware and software functionality. The ADE7753 evaluation
board, together with the ADE7753 d ata sheet and the EVAL-
ADE7753EB data sheet, provides a complete evaluation
platform for the ADE7753.
FUNCTIONAL BLOCK DIAGRAM
AGND
AV DD
DV DD DGND
+5V
V+
V–
V1P
FILTER
NETWORK
DOUT
SCLK
DIN
CS
RESET
V1N
74HC08
ADE7753
AGND
CONNECTOR
TO PC
PARALLEL
PORT
74HC08
FILTER
NETWORK
AND
ATTENUATION
V2N
V2P
BNC
EXTERNAL
CLOCK IN
BNC
CF
OPTICALLY
COUPLED
FREQUENCY
OUTPUT
EXTERNAL 2.5V
REFERENCE
AD780
CF
ZX
SAG
IRQ
PROTOTYPE
AREA
Figure 1.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, M A 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.326.8703
© 2004 Analog Devices, Inc. All rights reserved.
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EVAL-ADE7753EB
REVISION HISTORY
4/04—Revision 0: Initial Version
Rev. 0 | Page 2 of 20
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EVAL-ADE7753EB
ANALOG INPUTS (SK1 AND SK2)
Voltage and current signals are connected at the screw terminals
SK1 and SK2, respectively. All analog input signals are filtered
using the on-board antialiasing filters before being presented to
the analog inputs of the ADE7753. The default component
values, which are shipped with the evaluation board, are the
recommended values for the ADE7753. Users can easily change
these components if they are familiar with selecting the
component values for the analog input filters. Interested users
are encouraged to refer to the ADE7753 data sheet for a more
comprehensive description of the antialiasing filters and their
function.
USING A DI/DT SENSOR AS THE CURRENT
TRANSDUCER
Figure 3 shows how a di/dt sensor can be used as a current
transducer in a signal-phase, 2-wire distribution system. A di/dt
sensor is typically made from an air-core coil. Because of the
mutual inductance between the coil and the phase wire, a
voltage signal is output from the coil, which is proportional to
the time differentiation of the current (di/dt).
PHASE
WIRE
J P1 5
J P1
TP1
CURRENT SENSE INPUTS (SK2)
SK2 is a 3-way connection block that allows the ADE7753 to be
connected to a current transducer. Figure 2 s hows the connector
SK2 and the filtering network provided on the evaluation board.
V1P
100 Ω
1k Ω
JP2
C11 33nF
C50 33nF
J P2 5
J P3
TP2
V1N
100 Ω
1k Ω
JP4
C21 33nF
C51 33nF
The resistors SH1A and SH1B are by default not populated.
They should be used as burden resistors when a CT is used as
the current transducer (see the Using a CT as the Current
Tr a n s du c e r s e c t i on ) .
ADE7753
di/dt
CURRENT
SENSOR
FULL-SCALE
DIFFERENTIAL INPUT = 62.5mV
AT GAIN = +8
The RC networks R41/C11 and R42/C21 provide attenuation
of high frequency noise and equalize the 20 dB/dec gain at high
frequency when the di/dt sensor is used as the current
Transducer s ection). These RC networks are easily disabled by
placing JP15 and JP25 and removing C11 and C21 (socketed).
Figure 3. di/dt Sensor Connection to Current Channel
The di/dt sensor outputs a voltage by mutual inductance. When
using a di/dt sensor as the current sensor, Jumpers JP15/JP25
and JP1/JP3 should be left open. Both sets of filters are
necessary to provide the antialiasing filters (see Figure 3) .
In theory, air-core di/dt sensors have an associated phase shift
of +90° at all input frequencies. This phase shift is compensated
by the −90° phase shift of the integrator. Additional phase error,
from external component mismatch, for example, can be
corrected by writing to the phase calibration register
(PHCAL[7:0]) in the ADE7753. The software supplied with the
ADE7753 evaluation board allows users to adjust the phase
calibration register. See the Evaluation Software s ection for
more information.
The RC networks are the antialiasing filters required by the on-
chip ADCs. The default corner frequency for these low-pass
filters (LPF) is selected as 4.8 kHz (1 kΩ and 33nF). These filters
can easily be adjusted by replacing the components on the
evaluation board.
SH1A
JP15
R41
JP1
TP1
R50
V1P
SK2 1
100 Ω
1k Ω
For this example, notice that the maximum analog input range
on Channel 1 is set to 62.5 mV, and the gain for Channel 1 has
been set to 8. The maximum analog input range and gain are set
via the gain register (GAIN). See the ADE7753 data sheet. The
evaluation software allows users to configure the channel range
and gain. The maximum peak differential signal on Channel 1 is
0.5 V (at Gain = +1).
JP2
C11 33nF
C50 33nF
JP25
JP3
TP2
R42
R51
V1N
SK2 2
100 Ω
1k Ω
JP4
C21 33nF
C51 33nF
ADE7753
SK2 3
SH1B
Figure 2. Current Channel on the ADE7753 Evaluation Board
Rev. 0 | Page 3 of 20
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EVAL-ADE7753EB
USING A CT AS THE CURRENT TRANSDUCER
Figure 4 shows how a CT can be used as a current transducer in
a signal phase 3-wire distribution system. This is how electrical
energy is distributed to residential users in the United States.
Phase A and Phase B are nominally 180° out of phase. The
vector addition of the two currents is easily achieved by using
two primary turns of opposite polarity on the CT.
USING A SHUNT RESISTOR AS THE CURRENT
TRANSDUCER
Figure 5 shows how a shunt resistor can be used to perform the
current-to-voltage conversion required for the ADE7753. A
shunt is a cost-effective way to perform the current-to-voltage
conversion in a 2-wire, single-phase application. No isolation is
required in a 2-wire application, and the shunt has advantages
over the CT arrangement. For example, a shunt does not suffer
from dc saturation problems, and the phase response of the
shunt is linear over a very wide dynamic range. Although the
shunt is predominately resistive, it does have parasitic reactive
elements (inductance) that can become significant, even at
50 Hz/60 Hz. This means that there can be a small phase shift
associated with the shunt. Once it is understood, the phase shift
is easily compensated for with the filter network R41/C11 and
R42/C21 (see Application Note AN-559 for more details).
PHASE B
SH1A
2.8 Ω
I MAX = 80A
CT
1:1800
JP15
JP1
TP1
V1P
100 Ω
1k Ω
355mV
RMS
JP2
C50 33nF
JP25
JP3
TP2
V1N
100 Ω
1k Ω
JP4
C51 33nF
PHASE A
ADE7753
SH1B
2.8 Ω
The shunt used in this example is a 200 µΩ Manganin® type.
The resistance of the shunt should be as low as possible in order
to avoid excessive power dissipation in the shunt. Figure 5
shows how the shunt can be connected to the evaluation board.
Two sense wires should be soldered to the shunt as shown at the
copper/Manganin junctions. These sense wires should be
formed into a twisted pair to reduce the loop area that reduces
antenna effects. A connection for the common-mode voltage
can be made at the connection point for the current carrying
conductor (see Figure 5) .
FULL-SCALE
DIFFERENTIAL INPUT = 250mV
AT GAIN = +2
Figure 4. CT Connection to Current Channel
The CT secondary current is converted to a voltage by using a
burden resistance across the secondary winding outputs. Care
should be taken when using a CT as the current transducer. If
the secondary is left open, i.e., no burden is connected, a large
voltage could be present at the secondary outputs. This can
cause an electrical shock hazard and potentially damage
electronic components.
TWISTED-PAIR
CONNECTION
J P1 5
JP1
When using a CT as the current sensor, the phase compensation
network for a shunt application should be disabled. This is
achieved by closing Jumpers JP15/JP25 and removing C11/C21.
The antialiasing filters should be enabled by opening
Jumpers JP1/JP3 (see Figure 4) .
200 µΩ
TP1
V1P
100 Ω
1k Ω
16mV
RMS
JP2
C11 33nF
C50 33nF
J P2 5
JP3
TP2
V1N
100 Ω
1k Ω
80A
JP4
C21 33nF
C51 33nF
Most CTs have an associated phase shift of between 0.1° and 1°
at 50 Hz/60 Hz. This phase shift or phase error can lead to
significant energy measurement errors, especially at low power
factors. However, this phase error can be corrected by writing to
the phase calibration register (PHCAL[7:0]) in the ADE7753.
The software supplied with the ADE7753 evaluation board
allows users to adjust the phase calibration register. See the
Evaluation Software s ection for more information.
ADE7753
FULL-SCALE
DIFFERENTIAL INPUT = 31.25mV
AT GAIN = +16
BVM-D-R0002-5.0
Figure 5. Shunt Connection to Current Channel
For this example, notice that the maximum analog input range
on Channel 1 is set to 250 mV, and the gain for Channel 1 has
be set to 2. The maximum analog input range and gain are set
via the gain register (GAIN). See the ADE7753 data sheet. The
evaluation software allows users to configure the channel range
and gain.
Rev. 0 | Page 4 of 20
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EVAL-ADE7753EB
VOLTAGE SENSE INPUTS
The voltage input connections on the ADE7753 evaluation
board can be directly connected to the line voltage source.
The line voltage is attenuated using a simple resistor divider
network before it is presented to the ADE7753. Because of the
relatively large signal on this channel and the small dynamic
range requirement, the voltage channel can be configured in a
single-ended configuration. Figure 6 shows a typical connection
for the line voltage.
Note that the analog input V2N is connected to AGND via the
antialiasing filter R57/C54 using JP10. Also, Jumper JP9 should
be left open.
The voltage attenuation network is made up of R53, R54, and
R56. The maximum signal level permissible at V2P is 0.5 V
peak. Although the ADE7753 analog inputs can withstand ±6 V
without risk of permanent damage, the signal range should not
exceed ±0.5 V with respect to AGND for specified operation.
The attenuation network can be easily modified by the user to
accommodate any input signal levels. However, the value of R56
(1 kΩ) should not be altered as the phase response of Channel 2
should match the phase response of Channel 1 (see Application
Note AN-559 ) .
PHASE
JP 9
TP5
R57
SK1 1
V2N
1k Ω
JP10
C54 33nF
J P7
TP4
JP51
SK1 2
R53
R54
V2P
100mV RMS
TO
250mV RMS
499k Ω
499k Ω
R56
1k Ω
C53
33nF
JP8
ATTENUATION
NETWORK
ADE7753
100V RMS TO 250V RMS
NEUTRAL
Figure 6. Voltage Channel on the ADE7753 Evaluation Board
Rev. 0 | Page 5 of 20
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