3-Channel, Sigma-Delta ADC with SPI
Data Sheet
ADE7903
FEATURES
One (ADE7903) 24-bit, Σ-Δ ADC (simultaneously sampling
with three ADE7912/ADE7913 ADCs)
On-chip temperature sensor
4-wire SPI serial interface
Standalone 24-bit, Σ-Δ ADC
Up to four ADE7903 and ADE7912/ADE7913 devices clocked
from a single crystal or an external clock
Synchronization of multiple ADE7903 and ADE7912/ADE7913
devices
±31.25 mV peak input range for current channel
±500 mV peak input range for voltage channels
Single 3.3 V supply
20-lead, wide body SOIC package
Operating temperature: −40°C to +85°C
APPLICATIONS
3-phase shunt-based polyphase meters with neutral channel
measurement
Single-phase meters
Power quality monitoring
Solar inverters
Process monitoring
Standalone ADCs
Protective devices
Isolated sensor interfaces
Industrial programmable logic controllers (PLCs)
TYPICAL APPLICATION CIRCUIT
Figure 1.
GENERAL DESCRIPTION
The ADE7903 is a nonisolated, 3-channel, Σ-Δ analog-to-digital
converter (ADC) for the neutral line of polyphase energy
metering applications using shunt current sensors. The
ADE7903 can also be used for single-phase energy metering
and other standalone ADC applications. The ADE7903 features
three 24-bit ADCs. The current ADC provides a 67 dBFS
signal-to-noise ratio (SNR) over a 3.3 kHz signal bandwidth,
whereas the voltage ADCs provide an SNR of 72 dBFS over the
same bandwidth. One channel is dedicated to measuring the
voltage across a shunt when the shunt is used for current sensing.
Up to two additional channels are dedicated to measuring
voltages, which are usually sensed using resistor dividers.
One voltage channel can be used to measure the temperature
of the die via an internal sensor. The ADE7903 includes three
channels: one current channel and two voltage channels.
Together with the ADE7912/ADE7913, the ADE7903 provides
a small form factor, 3-phase isolated solution with a neutral
measurement. The three phases are isolated with ADE7912/
ADE7913 devices, while the neutral line is not isolated with the
ADE7903.
The ADE7903 configuration and status registers are accessed
via a bidirectional SPI serial port for easy interfacing with
microcontrollers.
The ADE7903 can be clocked from a crystal or an external
clock signal. To minimize the system bill of materials, the
master ADE7912/ADE7913 can drive the clocks of up to three
additional ADE7912/ADE7913 or ADE7903 devices.
Multiple ADE7912/ADE7913 and ADE7903 devices can be
synchronized to sample at the same moment and provide
coherent outputs. The ADE7903 can also be used individually
as a standalone ADC.
The ADE7903 is available in a 20-lead, Pb-free, wide body SOIC
package.
NEUTRAL PHASE
CISOLATION
BARRIER
LOAD
PHASE
APHASE
B
SPI INT E RFACE
PHASE A
ADE7912/
ADE7913
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_A
3.3V
PHASE B
ADE7912/
ADE7913
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_B
3.3V
PHASE C
ADE7912/
ADE7913
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_C
3.3V
NEUTRAL
LINE
ADE7903
IP
IM
V1P
VM
V2P
GND
MCU
3.3V
3.3V
SYSTEM
MICROCONTROLLER
GND
MCU
12458-001
Rev. 0 Document Feedback
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, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2014 Analog Devices, Inc. All rights reserved.
Technical Support www.analog.com
ADE7903 Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Typical Application Circuit ............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Functional Block Diagram .............................................................. 3
Specifications ..................................................................................... 4
Timing Characteristics ................................................................ 6
Absolute Maximum Ratings ............................................................ 7
Thermal Resistance ...................................................................... 7
ESD Caution .................................................................................. 7
Pin Configuration and Function Descriptions ............................. 8
Typical Performance Characteristics ............................................. 9
Test Circuit ...................................................................................... 11
Terminology .................................................................................... 12
Theory of Operation ...................................................................... 14
Analog Inputs .............................................................................. 14
Analog-to-Digital Conversion .................................................. 14
Reference Circuit ........................................................................ 16
CRC of ADC Output Values ..................................................... 16
Temperature Sensor ................................................................... 16
Protecting the Integrity of Configuration Registers .............. 17
CRC of Configuration Registers............................................... 17
ADE7903 Status .......................................................................... 17
Applications Information .............................................................. 18
ADE7903 in Polyphase Energy Meters ................................... 18
ADE7903 in Single-Phase Energy Meters ............................... 19
ADE7903 Clock .......................................................................... 20
SPI-Compatible Interface .......................................................... 20
Synchronizing Multiple ADE7912/ADE7913 and
ADE7903 Devices ....................................................................... 22
Power Management ........................................................................ 23
Power-Up and Initialization Procedures ................................. 23
Hardware Reset ........................................................................... 24
Software Reset ............................................................................. 24
Power-Down Mode .................................................................... 24
Layout Guidelines ........................................................................... 25
ADE7903 Evaluation Board ...................................................... 25
ADE7903 Version ....................................................................... 25
Register List ..................................................................................... 26
Outline Dimensions ....................................................................... 28
Ordering Guide .......................................................................... 28
REVISION HISTORY
12/14—Revision 0: Initial Version
Rev. 0 | Page 2 of 28
Data Sheet ADE7903
Rev. 0 | Page 3 of 28
FUNCTIONAL BLOCK DIAGRAM
Figure 2.
MISO
CLKOUT/
DREADY
CS
SCLK
ADC
LDO
IM
V1P
V2P
VM
REF
ADC
LDO
IP
GND
DIGITAL
BLOCK
AND
SPI PORT
XTAL2
XTAL1
GND
VDD
GND
VDD
GND
1
2
8
3
4
5
6
7
10
9
19
20
12
18
17
16
15
14
13
11
ADC
TEMPERATURE
SENSOR
VOLTAGE
REFERENCE
MOSI
ADE7903
12458-002
ADE7903 Data Sheet
SPECIFICATIONS
VDD = 3.3 V ± 10%, G N D = 0 V, o n -chip reference, XTAL1 = 4.096 MHz, TMIN to TMAX = −40°C to +85°C, TA = 25°C (typical), unless
otherwise noted.
Table 1.
Parameter Min Typ Max Unit Test Conditions/Comments
ANALOG INPUTS
1
Pseudo Differential Signal Voltage Range
Between IP and IM Pins
−31.25 +31.25 mV peak IM pin connected to GND
Pseudo Differential Signal Voltage Range
Between V1P and VM Pins and Between
V2P and VM Pins
−500 +500 mV peak Pseudo differential inputs between V1P and
VM pins and between V2P and VM pins; VM
pin connected to GND
Maximum VM and IM Voltage −25 +25 mV
Crosstalk −90 dB IP and IM inputs set to 0 V (GND) when V1P
and V2P inputs at full scale
−105 dB V2P and VM inputs set to 0 V (GND) when IP and
V1P inputs at full scale; V1P and VM inputs set
to 0 V (GND) when IP and V2P inputs at full scale
Input Impedance to Ground (DC)
IP, IM, V1P, and V2P Pins 480 kΩ
VM Pin 240 kΩ
Current Channel ADC Offset Error −2 mV
Voltage Channels ADC Offset Error −35 mV
ADC Offset Drift over Temperature ±200 ppm/°C V1 channel only
Gain Error −4 +4 %
Gain Drift over Temperature −135 +135 ppm/°C Current channel
−85 +85 ppm/°C V1 and V2 channels
AC Power Supply Rejection, PSR −90 dB VDD = 3.3 V + 120 mV rms (50 Hz/100 Hz),
IP = V1P = V2P = GND
DC Power Supply Rejection, PSR −80 dB VDD = 3.3 V ± 330 mV dc, IP = 6.25 mV rms,
V1P = V2P = 100 mV rms
TEMPERATURE SENSOR
Accuracy ±5 °C
WAVEFORM SAMPLING—CURRENT CHANNEL1
Signal-to-Noise Ratio, SNR 67 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
68 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
72 dBFS ADC_FREQ = 2 kHz, BW = 825 Hz
74 dBFS ADC_FREQ = 2 kHz, BW = 500 Hz
Signal-to-Noise-and-Distortion Ratio, SINAD 66 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
68 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
72 dBFS ADC_FREQ = 2 kHz, BW = 825 Hz
73 dBFS ADC_FREQ = 2 kHz, BW = 500 Hz
Total Harmonic Distortion, THD −79 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
−78 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
−82
dBFS
ADC_FREQ = 2 kHz, BW = 825 Hz
−82
dBFS
ADC_FREQ = 2 kHz, BW = 500 Hz
Spurious-Free Dynamic Range, SFDR 83 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
83 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
85 dBFS ADC_FREQ = 2 kHz, BW = 825 Hz
85 dBFS ADC_FREQ = 2 kHz, BW = 500 Hz
Rev. 0 | Page 4 of 28
Data Sheet ADE7903
Parameter Min Typ Max Unit Test Conditions/Comments
VOLTAGE CHANNELS1
Signal-to-Noise Ratio, SNR 72 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
74 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
77 dBFS ADC_FREQ = 2 kHz, BW = 825 Hz
79
dBFS
ADC_FREQ = 2 kHz, BW = 500 Hz
Signal-to-Noise-and-Distortion Ratio, SINAD 72 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
74 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
77 dBFS ADC_FREQ = 2 kHz, BW = 825 Hz
78 dBFS ADC_FREQ = 2 kHz, BW = 500 Hz
Total Harmonic Distortion, THD −83 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
−83 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
−85 dBFS ADC_FREQ = 2 kHz, BW = 825 Hz
−85 dBFS ADC_FREQ = 2 kHz, BW = 500 Hz
Spurious-Free Dynamic Range, SFDR 86 dBFS ADC_FREQ = 8 kHz, BW = 3300 Hz
86 dBFS ADC_FREQ = 8 kHz, BW = 2000 Hz
87 dBFS ADC_FREQ = 2 kHz, BW = 825 Hz
87 dBFS ADC_FREQ = 2 kHz, BW = 500 Hz
CLKIN2 All specifications for CLKIN = 4.096 MHz
Input Clock Frequency
3.6
4.096
MHz
CLKIN Duty Cycle 45 50 55 %
XTAL1 Logic Inputs
Input High Voltage, VINH 2.4 V
Input Low Voltage, VINL 0.8 V
XTAL1 Total Capacitance3 40 pF
XTAL2 Total Capacitance3 40 pF
CLKOUT Delay from XTAL14 100 ns
LOGIC INPUTS—MOSI, SCLK, CS
Input High Voltage, VINH 2.4 V
Input Low Voltage, VINL 0.8 V
Input Current, IIN 0.015 1 µA
Input Capacitance, CIN 10 pF
LOGIC OUTPUTS—CLKOUT/DREADY AND MISO
Output High Voltage, VOH 2.5 V ISOURCE = 800 µA
Output Low Voltage, VOL 0.4 V ISINK = 2 mA
POWER SUPPLY For specified performance
VDD Pin 2.97 3.63 V Minimum = 3.3 V − 10%;
maximum = 3.3 V + 10%
Supply Current (IDD) 5 5.1 6.2 mA
2
mA
No CLKIN signal at XTAL1 pin
1 See the Terminology section for a definition of the parameters.
2 CLKIN is the internal clock of the ADE7903. It is the frequency at which the device is clocked at the XTAL1 pin.
3 XTAL1/XTAL2 total capacitances refer to the net capacitances on each pin. Each capacitance is the sum of the parasitic capacitance at the pin and the capacitance of
the ceramic capacitor connected between the pin and GND. See the ADE7903 Clock section for more details.
4 CLKOUT delay from XTAL1 is the delay that occurs from a high to low transition at the XTAL1 pin to a synchronous high to low transition at the CLKOUT/DREADY pin
when CLKOUT functionality is enabled.
5 Supply current specified with the two VDD pins connected externally from the same power supply (see the Pin Configuration and Function Descriptions section).
Rev. 0 | Page 5 of 28
ADE7903 Data Sheet
TIMING CHARACTERISTICS
VDD = 3.3 V ± 10%, GND = 0 V, on-chip reference, CLKIN = 4.096 MHz, TMIN to TMAX = −40°C to +85°C.
Table 2. SPI Interface Timing Parameters
Parameter Symbol Min Max Unit
CS to SCLK Positive Edge tSS 50 ns
SCLK Frequency1 250 5600 kHz
SCLK Low Pulse Width tSL 80 ns
SCLK High Pulse Width tSH 80 ns
Data Output Valid After SCLK Edge tDAV 80 ns
Data Input Setup Time Before SCLK Edge
t
DSU
70
ns
Data Input Hold Time After SCLK Edge tDHD 20 ns
Data Output Fall Time tDF 20 ns
Data Output Rise Time tDR 20 ns
SCLK Rise Time tSR 20 ns
SCLK Fall Time tSF 20 ns
MISO Disable After CS Rising Edge tDIS 5 40 ns
CS High After SCLK Edge tSFS 0 ns
1 Minimum and maximum specifications are guaranteed by design.
Figure 3. SPI Interface Timing
Figure 4. Load Circuit for Timing Specifications
MSB LSB
LSB IN
INTERMEDIATE BITS
INTERMEDIATE BITS
tSFS
tDIS
tSS
tSL
tDF
tSH
tDHD
tDAV
tDSU
tSR
tSF
tDR
MSB IN
MOSI
MISO
SCLK
CS
12458-003
2mA I
OL
800µA I
OH
1.6V
TO OUTPUT
PIN C
L
50pF
12458-004
Rev. 0 | Page 6 of 28
Data Sheet ADE7903
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 3.
Parameter Rating
VDD to GND −0.3 V to +3.7 V
Analog Input Voltage to GND, IP, I M,
V1P, V2P, V M
−2 V to +2 V
Reference Input Voltage to GND −0.3 V to VDD + 0.3 V
Digital Input Voltage to GND −0.3 V to VDD + 0.3 V
Digital Output Voltage to GND
−0.3 V to VDD + 0.3 V
Operating Temperature
Industrial Range −40°C to +85°C
Storage Temperature Range −65°C to +150°C
Lead Temperature (Soldering, 10 sec)1 260°C
1 Analog Devices, Inc., recommends that reflow profiles used in soldering
RoHS compliant devices conform to J-STD-020D.1 from JEDEC. Refer to
JEDEC for the latest revision of this standard.
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
THERMAL RESISTANCE
θJA and θJC are specified for the worst-case conditions, that is, a
device soldered in a circuit board for surface-mount packages.
Table 4. Thermal Resistance
Package Type θJA θJC Unit
20-Lead SOIC_W 79 24.7 °C/W
ESD CAUTION
Rev. 0 | Page 7 of 28
ADE7903 Data Sheet
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 5. Pin Configuration
Table 5. Pin Function Descriptions
Pin No. Mnemonic Description
1, 19 VDD Supply Voltage. These pins provide the supply voltage for the ADE7903. Maintain the supply voltage at
3.3 V ± 10% for specified operation. Decouple each VDD pin to GND with a ceramic 100 nF capacitor and
a single 10 µF capacitor in parallel. Connect the VDD pins externally.
2, 10, 11, 20 GND Ground Reference. Connect the GND pins externally.
3, 4, 5
V2P, V1P, VM
Analog Inputs for the Voltage Channels. The voltage channels are used with the voltage transducers.
V2P
and V1P are pseudo differential voltage inputs with a maximum signal level of ±500 mV with respect
to VM for specified operation. Use these pins with the related input circuitry, as shown in Figure 18. If V1P
or V2P is not used, connect it to the VM pin.
6, 7 IM, IP Analog Inputs for the Current Channel. The current channel is used with shunts. IM and IP are pseudo
differential voltage inputs with a maximum differential level of ±31.25 mV. Use these pins with the
related input circuitry, as shown in Figure 18.
8 LDO 2.5 V Output of the Analog Low Dropout (LDO) Regulator. Decouple this pin with a 4.7 µF capacitor in
parallel with a ceramic 100 nF capacitor to GND. Do not connect external load circuitry to this pin.
9 REF Voltage Reference. This pin provides access to the on-chip voltage reference. The on-chip reference has a
nominal value of 1.2 V. Decouple this pin to GND with a 4.7 µF capacitor in parallel with a ceramic 100 nF
capacitor.
12 CLKOUT/DREADY Clock Output (CLKOUT). When CLKOUT functionality is selected (see the Synchronizing Multiple
ADE7912/ADE7913 and ADE7903 Devices section for details), the ADE7903 generates a digital signal
synchronous to the master clock at the XTAL1 pin. Use CLKOUT to provide a clock to other ADE7912/
ADE7913 and ADE7903 devices on the board.
Data Ready, Active Low (DREADY). When the DREADY functionality is selected (see the Synchronizing
Multiple ADE7912/ADE7913 and ADE7903 Devices section for details), the ADE7903 generates an active
low signal synchronous to the ADC output frequency. Use this signal to start reading the ADC outputs of
the ADE7903.
13 XTAL1 Master Clock Input. An external clock can be provided at this logic input. The CLKOUT/DREADY signal of
another appropriately configured ADE7903 (see the Synchronizing Multiple ADE7912/ADE7913 and
ADE7903 Devices section for details) can be provided at this pin. Alternatively, a crystal with a maximum
drive level of 0.5 mW and an equivalent series resistance (ESR) of 20 Ω can be connected across XTAL1 and
XTAL2 to provide a clock source for the ADE7903. The clock frequency for specified operation is 4.096 MHz,
but lower frequencies down to 3.6 MHz can be used. See the ADE7903 Clock section for more details.
14 XTAL2 Crystal, Second Input. A crystal with a maximum drive level of 0.5 mW and an ESR of 20 Ω can be
connected across XTAL2 and XTAL1 to provide a clock source for the ADE7903.
15
MISO
Data Output for SPI Port. Pull up this pin with a 10 kΩ resistor (see the ADE7903 Clock section for details).
16 MOSI Data Input for SPI Port.
17 SCLK Serial Clock Input for SPI Port. All serial data transfers are synchronized to this clock (see the ADE7903
Clock section).
18 CS Chip Select for SPI Port.
ADE7903
TOP VIEW
(No t t o Scal e)
VDD
1
GND
2
V2P
3
V1P
4
GND
20
VDD
19
CS
18
SCLK
17
VM
5
MOSI
16
IM
6
MISO
15
IP
7
XTAL2
14
LDO
8
XTAL1
13
REF
9
CLKOUT/DREADY
12
GND
10
GND
11
12458-005
Rev. 0 | Page 8 of 28
Data Sheet ADE7903
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 6. Current Channel Fast Fourier Transform (FFT), ±31.25 mV, 50 Hz
Pseudo Differential Input Signal, ADC_FREQ = 8 kHz, BW = 3300 Hz
Figure 7. Current Channel FFT, ±31.25 µV, 50 Hz Pseudo Differential Input
Signal, ADC_FREQ = 8 kHz, BW = 3300 Hz
Figure 8. Voltage Channel V1 FFT, ±500 mV, 50 Hz Pseudo Differential Input
Signal, ADC_FREQ = 8 kHz, BW = 3300 Hz
Figure 9. Voltage Channel V1 FFT, ±500 µV, 50 Hz Pseudo Differential Input
Signal, ADC_FREQ = 8 kHz, BW = 3300 Hz
Figure 10. Voltage Channel V2 FFT, ±500 mV, 50 Hz Pseudo Differential Input
Signal, ADC_FREQ = 8 kHz, BW = 3300 Hz
Figure 11. Voltage Channel V2 FFT, ±500 µV, 50 Hz Pseudo Differential Input
Signal, ADC_FREQ = 8 kHz, BW = 3300 Hz
0
–180
–160
–140
–120
–100
–80
–60
–40
–20
0500 1000 1500 2000 2500 3000 3500 4000 4500
AMPLITUDE ( dB)
FRE Q UE NCY ( Hz )
SNR = 66. 55dB
THD = –88.71d B
SINAD = 66.53d B
SF DR = 91.2d B
12458-006
0
–160
–140
–120
–100
–80
–60
–40
–20
0500 1000 1500 2000 2500 3000 3500 4000 4500
AMPLITUDE ( dB)
FRE Q UE NCY ( Hz )
SNR = 6. 43dB
THD = –36.07d B
SINAD = 6.43d B
SF DR = 41.28d B
12458-007
0
–180
–160
–140
–120
–100
–80
–60
–40
–20
0500 1000 1500 2000 2500 3000 3500 4000 4500
AMPLITUDE ( dB)
FRE Q UE NCY ( Hz )
SNR = 75. 11dB
THD = –79.55d B
SINAD = 73.78d B
SF DR = 79.62d B
12458-008
0
–180
–160
–140
–120
–100
–80
–60
–40
–20
0500 1000 1500 2000 2500 3000 3500 4000 4500
AMPLITUDE ( dB)
FRE Q UE NCY ( Hz )
SNR = 15. 32dB
THD = –47.02d B
SINAD = 15.32d B
SF DR = 53.71d B
12458-009
0
–180
–160
–140
–120
–100
–80
–60
–40
–20
0500 1000 1500 2000 2500 3000 3500 4000 4500
AMPLITUDE ( dB)
FRE Q UE NCY ( Hz )
SNR = 74. 99dB
THD = –79.47d B
SINAD = 73.66d B
SF DR = 79.561d B
12458-010
0
–180
–160
–140
–120
–100
–80
–60
–40
–20
0500 1000 1500 2000 2500 3000 3500 4000 4500
AMPLITUDE ( dB)
FRE Q UE NCY ( Hz )
SNR = 15. 27dB
THD = –45.83d B
SINAD = 15.27d B
SF DR = 53.59d B
12458-011
Rev. 0 | Page 9 of 28
ADE7903 Data Sheet
Figure 12. Cumulative Histogram of the Current Channel ADC Gain
Temperature Coefficient for Temperatures Between −40°C and +25°C
Figure 13. Cumulative Histogram of the Current Channel ADC Gain
Temperature Coefficient for Temperatures Between 25°C and 85°C
Figure 14. Cumulative Histogram of the Voltage Channel V1 ADC Gain
Temperature Coefficient for Temperatures Between −40°C and +25°C
Figure 15. Cumulative Histogram of the Voltage Channel V1 ADC Gain
Temperature Coefficient for Temperatures Between 25°C and 85°C
Figure 16. Cumulative Histogram of the Voltage Channel V2 ADC Gain
Temperature Coefficient for Temperatures Between −40°C and +25°C
Figure 17. Cumulative Histogram of the Voltage Channel V2 ADC Gain
Temperature Coefficient for Temperatures Between 25°C and 85°C
100
90
80
70
60
50
40
30
20
10
0
–100 –80 –60 –40 –20 020 40 60 80 100
PERCENTAG E OF DIST RIBUT ION ( %)
TEMPERATURE COEFFICIENT (ppm/°C)
12458-012
100
90
80
70
60
50
40
30
20
10
0
–100 –80 –60 –40 –20 020 40 60 80 100
PERCENTAG E OF DIST RIBUT ION ( %)
TEMPERATURE COEFFICIENT (ppm/°C)
12458-013
100
90
80
70
60
50
40
30
20
10
0
–100 –80 –60 –40 –20 020 40 60 80 100
PERCENTAG E OF DIST RIBUT ION ( %)
TEMPERATURE COEFFICIENT (ppm/°C)
12458-014
100
90
80
70
60
50
40
30
20
10
0
–100 –80 –60 –40 –20 020 40 60 80 100
PERCENTAG E OF DIST RIBUT ION ( %)
TEMPERATURE COEFFICIENT (ppm/°C)
12458-015
100
90
80
70
60
50
40
30
20
10
0
–100 –80 –60 –40 –20 020 40 60 80 100
PERCENTAG E OF DIST RIBUT ION ( %)
TEMPERATURE COEFFICIENT (ppm/°C)
12458-016
100
90
80
70
60
50
40
30
20
10
0
–100 –80 –60 –40 –20 020 40 60 80 100
PERCENTAG E OF DIST RIBUT ION ( %)
TEMPERATURE COEFFICIENT (ppm/°C)
12458-017
Rev. 0 | Page 10 of 28
Data Sheet ADE7903
Rev. 0 | Page 11 of 28
TEST CIRCUIT
Figure 18. Test Circuit
ADE7912
A
/
ADE7913
A
CLKOUT/DREADY
19
MISO
15
MOSI
16
SCLK
17
XTAL1
13
XTAL2
14
12
GND
11
20
TS4148
TS4148
TS4148
TS4148
TS4148
150Ω
FERRITE
150Ω
FERRITE
150Ω
FERRITE
150Ω
FERRITE
150Ω
FERRITE
IP
IM
33nF
33nF
33nF
100nF
4.7µF
100nF
4.7µF
V1P
VM
V2P
7
6
4
5
3
GND
ISO
VDD
ISO
2
1
GND
ISO
LDO
10
8
9
REF
GND
VDD
SAME AS IN
ADE7912
A
/
ADE7913
A
SAME AS IN
ADE7912
A
/
ADE7913
A
T
P4
T
P5
10µF
TO MCU
100nF
330kΩ330kΩ330kΩ
330kΩ330kΩ330kΩ
1kΩ
1kΩ
1kΩ
33nF1kΩ
33nF1kΩ
10µF 100nF
3.3V
TP3
TP1
TP2
CS
18
TO MCU
TO MCU
TO MCU
TO MCU
TO MCU
TO MCU
18
19
ADE7912
B
/
ADE7913
B
15
13
14
17
16
12
11
20
SAME AS IN
ADE7912
A
/
ADE7913
A
1
2
3
4
5
6
7
8
9
10
18
19
ADE7912
C
/
ADE7913
C
15
13
14
17
16
12
11
20
SAME AS IN
ADE7912
A
/
ADE7913
A
1
2
3
4
5
6
7
8
9
10
NOTES
1. ADE7912
X
/ADE7913
X
= PHASE X ADE7912/ADE7913, WHERE X = A, B, OR C.
3.3V
10kΩ
22pF 22pF
4.096MHz
ADE7903
N
CLKOUT/DREADY
MISO
MOSI
SCLK
XTAL1
XTAL2
GND
IP
IM
V1P
VM
V2P
GND
VDD
GND
LDO
REF
GND
VDD
CS
2
1
100nF
19
10µF100nF
3.3V
11
TO MCU
18
7
6
100nF
4.7µF
100nF
4.7µF
10
8
9
4
5
3
SAME AS IN
ADE7912
A
/
ADE7913
A
20
13
15
16
17
14
12
12458-018
ADE7903 Data Sheet
TERMINOLOGY
Pseudo Differential Signal Voltage Range Between IP and
IM, V1P and VM, and V2P and VM Pins
This range represents the peak-to-peak pseudo differential
voltage that must be applied to the ADCs to generate a full-scale
response when the IM and VM pins are connected to GND.
The IM and VM pins are connected to GND using antialiasing
filters (see Figure 18). Figure 19 illustrates the input voltage
range between IP and IM. Figure 20 illustrates the input voltage
range between V1P and VM and between V2P and VM.
Figure 19. Pseudo Differential Input Voltage Range Between IP and IM Pins
Figure 20. Pseudo Differential Input Voltage Range Between V1P and VM
Pins and Between V2P and VM Pins
Maximum VM and IM Voltage Range
This range represents the maximum allowed voltage at the VM
and IM pins relative to GND.
Crosstalk
Crosstalk represents leakage of signals, usually via capacitance
between circuits. Crosstalk is measured in the current channel
by setting the IP and IM pins to GND, supplying a full-scale
alternate differential voltage between the V1P and VM pins and
between the V2P and VM pins of the voltage channel, and
measuring the output of the current channel. It is measured in
the V1P voltage channel by setting the V1P and VM pins to
GND, supplying a full-scale alternate differential voltage at the IP
and V2P pins, and measuring the output of the V1P channel.
Crosstalk is measured in the V2P voltage channel by setting the
V2P and VM pins to GND, supplying a full-scale alternate
differential voltage at the IP and V1P pins, and measuring the
output of the V2P channel. The crosstalk is equal to the ratio
between the grounded ADC output value and its ADC full-scale
output value. The ADC outputs are acquired for 2 sec. Crosstalk
is expressed in decibels.
Input Impedance to Ground (DC)
The input impedance to ground represents the impedance
measured at each ADC input pin (IP, IM, V1P, V2P, and VM)
with respect to GND.
ADC Offset Error
ADC offset error is the difference between the average
measured ADC output code with both inputs connected to
GND and the ideal ADC output code. The magnitude of the
offset depends on the input range of each channel.
ADC Offset Drift over Temperature
The ADC offset drift is the change in offset over temperature.
It is measured at −40°C, +25°C, and +85°C. The offset drift over
temperature is computed as follows:
( )
( )
( )
( )
( ) ( )
( ) ( )
−×
−
−−×
−−
=
258525
2585
,
254025
2540
max Offset
OffsetOffset
Offset
OffsetOffset
Drift
Offset drift is expressed in ppm/°C.
Gain Error
The gain error in the ADCs represents the difference between the
measured ADC output code (minus the offset) and the ideal
output code when the internal voltage reference is used (see
the Analog-to-Digital Conversion section). The difference is
expressed as a percentage of the ideal code. It represents the
overall gain error of one current or voltage channel.
IP
IM
IP – IM
0V
0V
0V
+31.25mV
–31.25mV
+31.25mV
–31.25mV
12458-019
+500mV
–500mV
+500mV
–500mV
V1P, V2P
V1P – VM,
V2P – VM
VM
0V
0V
0V
12458-020
Rev. 0 | Page 12 of 28
Data Sheet ADE7903
Gain Drift over Temperature
This temperature coefficient includes the temperature variation
of the ADC gain and of the internal voltage reference. It represents
the overall temperature coefficient of one current or voltage
channel. With the internal voltage reference in use, the ADC
gain is measured at −40°C, +25°C, and +85°C. Then, the
temperature coefficient is computed as follows:
( )
( )
( )
( )
( ) ( )
( )
( )
−×
−
−−×
−−
=258525
2585
,
254025
2540
max Gain
GainGain
Gain
GainGain
Drift
Gain drift is measured in ppm/°C.
Power Supply Rejection (PSR)
PSR quantifies the measurement error as a percentage of
reading when the power supplies are varied. For the ac PSR
measurement, a reading at nominal supplies (3.3 V) is taken
when the voltage at the input pins is 0 V. A second reading is
obtained with the same input signal levels when an ac signal
(120 mV rms at 50 Hz or 100 Hz) is introduced onto the supply.
Any error introduced by this ac signal is expressed as a
percentage of the reading (power supply rejection ratio, PSRR).
PSR = 20log10 (PSRR).
For the dc PSR measurement, a reading at nominal supplies
(3.3 V) is taken when the voltage between the IP and IM pins is
6.25 mV rms, and the voltages between the V1P and VM pins
and between the V2P and VM pins are 100 mV rms. A second
reading is obtained with the same input signal levels when the
power supplies are varied by ±10%. Any error introduced is
expressed as a percentage of the reading (PSRR). Then PSR =
20log10 (PSRR).
Signal-to-Noise Ratio (SNR)
SNR is the ratio of the rms value of the actual input signal to the
rms sum of all other spectral components below the Nyquist
frequency, excluding harmonics and dc. The spectral components
are calculated over a 2 sec window. The value for SNR is expressed
in decibels relative to full scale (dBFS).
Signal-to-Noise-and-Distortion (SINAD) Ratio
SINAD is the ratio of the rms value of the actual input signal to
the rms sum of all other spectral components below the Nyquist
frequency, including harmonics but excluding dc. The spectral
components are calculated over a 2 sec window. The value for
SINAD is expressed in decibels relative to full scale (dBFS).
Total Harmonic Distortion (THD)
THD is the ratio of the rms sum of all harmonics (excluding the
noise components) to the rms value of the fundamental. The
spectral components are calculated over a 2 sec window. The value
for THD is expressed in decibels relative to full scale (dBFS).
Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio of the rms value of the actual input signal to
the rms value of the peak spurious component over the
measurement bandwidth of the waveform samples. The spectral
components are calculated over a 2 sec window. The value of
SFDR is expressed in decibels relative to full scale (dBFS).
Rev. 0 | Page 13 of 28
ADE7903 Data Sheet
THEORY OF OPERATION
ANALOG INPUTS
The ADE7903 has three analog inputs: one current channel and
two voltage channels. The current channel has two fully differential
voltage input pins, IP and IM, that accept a maximum differential
signal of ±31.25 mV.
The maximum VIP signal level is also ±31.25 mV. The maximum
VIM signal level allowed at the IM input is ±25 mV. Figure 21
shows a schematic of the input for the current channel and its
relation to the maximum IM pin voltage.
Figure 21. Maximum Input Level, Current Channel
Note that the current channel is used to sense the voltage across
a shunt. In this case, one pole of the shunt becomes the ground
of the meter (see Figure 28) and, therefore, the current channel
is used in a pseudo differential configuration, similar to the
voltage channel configuration (see Figure 22).
The voltage channel has two pseudo differential, single-ended
voltage input pins: V1P and V2P. These single-ended voltage
inputs have a maximum input voltage of ±500 mV with respect
to VM. The maximum signal allowed at the VM input is
±25 m V. Figure 22 shows a schematic of the voltage channel
inputs and their relation to the maximum VM voltage.
Figure 22. Maximum Input Level, Voltage Channels
ANALOG-TO-DIGITAL CONVERSION
The ADE7903 has three second-order Σ-Δ ADCs. For simplicity,
the block diagram in Figure 23 shows a first-order Σ-Δ ADC. The
converter is composed of the Σ-Δ modulator and the digital
low-pass filter (LPF).
Figure 23. First-Order Σ-Δ ADC
A Σ-Δ modulator converts the input signal into a continuous
serial stream of 1s and 0s at a rate determined by the sampling
clock. In the ADE7903, the sampling clock is equal to CLKIN/4
(1.024 MHz when CLKIN = 4.096 MHz). The 1-bit digital-to-
analog converter (DAC) in the feedback loop is driven by the
serial stream. The DAC output is subtracted from the input
signal. If the loop gain is high enough, the average value of the
DAC output (and, therefore, the bit stream) can approach that
of the input signal level. For any given input value in a single
sampling interval, the data from the 1-bit ADC is virtually
meaningless. A meaningful result is obtained only when a large
number of samples is averaged. This averaging is completed in
the second part of the ADC, the digital low-pass filter, after the
data is passed through the digital isolators. By averaging a large
number of bits from the modulator, the low-pass filter can
produce 24-bit data-words that are proportional to the input
signal level.
The Σ-Δ converter uses two techniques to achieve high resol-
ution from what is essentially a 1-bit conversion technique. The
first technique is oversampling. Oversampling means that the
signal is sampled at a rate (frequency) that is many times higher
than the bandwidth of interest. For example, when CLKIN =
4.096 MHz, the sampling rate in the ADE7903 is 1.024 MHz,
and the bandwidth of interest is 40 Hz to 3.3 kHz. Oversampling
has the effect of spreading the quantization noise (noise due to
sampling) over a wider bandwidth. With the noise spread more
thinly over a wider bandwidth, the quantization noise in the
bandwidth of interest is lowered, as shown in Figure 24.
Figure 24. Noise Reduction Due to Oversampling and
Noise Shaping in the Analog Modulator
However, oversampling alone is not sufficient to improve the
SNR in the band of interest. For example, an oversampling factor
of four is required to increase the SNR by a mere 6 dB (1 bit). To
keep the oversampling ratio at a reasonable level, it is possible to
shape the quantization noise so that the majority of the noise
lies at the higher frequencies. Noise shaping is the second
technique used to achieve high resolution. In the Σ-Δ modulator,
IP
IM
VIM
VIP
+31.25mV
0V
VIP VIP = ±31.25mV MAX P E AK
VIM = ±25mV MAX
–31.25mV
12458-021
V1P OR
V2P
VM
V
M
V
1
+500mV
0V
V
1
V
1
= ±500mV M AX P E AK
V
M
= ±25mV M AX
–500mV
12458-022
24
DIGITAL
LOW-PASS
FILTER
R
C
+
–
CLKIN/4
INTEGRATOR
V
REF
1-BI T DAC
LATCHED
COMPARATOR
ANALOG
LOW-PASS
FILTER
.....10100101.....
+–
12458-023
NOISE
SIGNAL
NOISE
SIGNAL
03.3 4512
FRE Q UE NCY ( kHz )
HIGH RESOLUTION
OUTPUT FROM
DIGITAL LPF
1024
03.3 4512
FRE Q UE NCY ( kHz ) 1024
DIGITAL FILTER SHAPED NOI S E
ANTIALIAS FILTER
(RC)
SAMPLING
FREQUENCY
12458-024
Rev. 0 | Page 14 of 28
Data Sheet ADE7903
the noise is shaped by the integrator, which has a high-pass type
response for the quantization noise. The result is that most of the
noise is at higher frequencies where it can be removed by the
digital low-pass filter. This noise shaping is shown in Figure 24.
The bandwidth of interest is a function of the input clock
frequency, the ADC output frequency (selectable by Bits[5:4]
(ADC_FREQ) in the CONFIG register; see the ADC Output
Values section for details), and Bit 7 (BW) of the CONFIG
register. When CLKIN is 4.096 MHz and the ADC output
frequency is 8 kHz, if BW is cleared to 0 (the default value), the
ADC bandwidth is 3.3 kHz. If BW is set to 1, the ADC bandwidth
is 2 kHz. Table 6 shows the ADC output frequencies and the
ADC bandwidth as a function of the input clock (CLKIN)
frequency. Three cases are shown: one for CLKIN = 4.096 MHz,
the typical clock input frequency value; one for CLKIN =
4.21 MHz, the maximum clock input frequency; and one for
CLKIN = 3.6 MHz, the minimum clock input frequency.
Antialiasing Filter
Figure 23 also shows an analog low-pass filter (RC) on the input
to the ADC. This filter is placed outside the ADE7903, and its role
is to prevent aliasing. Aliasing is an artifact of all sampled systems,
as shown in Figure 25. Aliasing refers to the frequency components
in the input signal to the ADC that are higher than half the
sampling rate of the ADC and appear in the sampled signal at a
frequency below half the sampling rate. Frequency components
above half the sampling frequency (also known as the Nyquist
frequency, that is, 512 kHz) are imaged or folded back down
below 512 kHz. This folding happens with all ADCs, regardless of
the architecture. In Figure 25, only frequencies near the sampling
frequency of 1.024 MHz move into the bandwidth of interest for
metering, that is, 40 Hz to 3.3 kHz or 40 Hz to 2 kHz. To attenuate
the high frequency noise (near 1.024 MHz) and prevent the
distortion of the bandwidth of interest, a low-pass filter must be
introduced. It is recommended that one RC filter with a corner
frequency of 5 kHz be used for the attenuation to be sufficiently
high at the sampling frequency of 1.024 MHz. The 20 dB per
decade attenuation of this filter is usually sufficient to eliminate
the effects of aliasing.
Figure 25. Aliasing Effects
ADC Transfer Function
All ADCs in the ADE7903 produce 24-bit signed output codes.
With a full-scale input signal of 31.25 mV on the current channel
and 0.5 V on the voltage channels, and with an internal reference
of 1.2 V, the ADC output code is nominally 5,320,000 and usually
varies for each ADE7903 around this value. The code from the
ADC can vary between 0x800000 (−8,388,608) and 0x7FFFFF
(+8,388,607), which is equivalent to an input signal level of
±49.27 mV on the current channel and ±0.788 V on the voltage
channels. However, for specified performance, do not exceed
the nominal range of ±31.25 mV for the current channel and
±500 mV for the voltage channels; ADC performance is
guaranteed only for input signals within these limits.
ADC Output Values
The ADC output values are stored in three 24-bit signed
registers, IWV, V1WV, and V2WV, at a rate defined by Bits[5:4]
(ADC_FREQ) in the CONFIG register. The output frequency is
8 kHz (CLKIN/512), 4 kHz (CLKIN/1024), 2 kHz (CLKIN/2048),
or 1 kHz (CLKIN/4096) based on ADC_FREQ being equal to
00, 01, 10, or 11, respectively, when CLKIN is 4.096 MHz.
The microcontroller reads the ADC output registers one at a time
or in burst mode. See the SPI Read Operation section and the SPI
Read Operation in Burst Mode section for more information.
Table 6. ADC Output Frequency and ADC Bandwidth as a Function of CLKIN Frequency
CLKIN
(MHz)
ADC_FREQ Bits in
CONFIG Register
ADC Output
Frequency (Hz)
ADC Bandwidth When BW Bit in
CONFIG Register Cleared to 0 (Hz)
ADC Bandwidth When BW Bit in
CONFIG Register Set to 1 (Hz)
4.096 00 8000 3300 2000
01 4000 1650 1000
10 2000 825 500
11 1000 412 250
4.21
00
8222
3391
2055
01 4111 1695 1027
10 2055 847 513
11 1027 423 256
3.6 00 7031 2900 1757
01 3515 1450 878
10 1757 725 439
11 878 362 219
ALIASING EFFECTS SAMPLING
FREQUENCY
IMAGE
FREQUENCIES
0 2 4 512
FRE Q UE NCY ( kHz ) 1024
12458-025
Rev. 0 | Page 15 of 28
ADE7903 Data Sheet
REFERENCE CIRCUIT
The nominal reference voltage at the REF pin is 1.2 V. This
reference voltage is used for the ADCs in the ADE7903.
Because the on-chip dc-to-dc converter cannot supply external
loads, the REF pin cannot be overdriven by a standalone
external voltage reference.
The voltage of the ADE7903 reference drifts slightly with
temperature. Table 1 lists the gain drift over temperature
specification of each ADC channel. This value includes the
temperature variation of the ADC gain, together with the
temperature variation of the internal voltage reference.
CRC OF ADC OUTPUT VALUES
Every output cycle, the ADE7903 computes the cyclic
redundancy check (CRC) of the ADC output values stored in
the IWV, V1WV, and V2WV registers. Bits[5:4] (ADC_FREQ)
in the CONFIG register determine the ADC output frequency
and, therefore, the update rate of the CRC. The CRC algorithm
is based on the CRC-16-CCITT algorithm. The registers are
introduced into a linear feedback shift register (LFSR) based
generator one byte at a time, least significant byte first, as shown in
Figure 26. Each byte is then used with the MSB first. The 16-bit
result is written in the ADC_CRC register.
Figure 26. CRC Calculation of ADC Output Values
Figure 27. LFSR Generator Used for ADC_CRC Calculation
Figure 27 shows how the LFSR works. The IWV, V1WV, and
V2WV registers form the [a71, a70,…, a0] bits used by the LFSR.
Bit a0 is Bit 7 of the first register to enter the LFSR; Bit a71 is
Bit 16 of V2WV, the last register to enter the LFSR. The
formulas that govern the LFSR are as follows:
bi(0) = 1, where i = 0, 1, 2, …, 15, the initial state of the bits that
form the CRC. Bit b0 is the LSB, and Bit b15 is the MSB.
gi, where i = 0, 1, 2, …, 15 are the coefficients of the generating
polynomial defined by the CRC-16-CCITT algorithm as
follows:
G(x) = x16 + x12 + x5 + 1 (1)
g0 = g5 = g12 = 1 (2)
All other gi coefficients are equal to 0.
FB(j) = aj − 1 XOR b15(j − 1) (3)
b0(j) = FB(j) AND g0 (4)
bi(j) = FB(j) AND gi XOR bi − 1(j − 1), i = 1, 2, 3, …, 15 (5)
Equation 3, Equation 4, and Equation 5 must be repeated for
j = 1, 2, …, 72. The value written into the ADC_CRC register
contains Bit bi(72), i = 0, 1, …, 15.
The ADC_CRC register can be read by executing an SPI
register read access or as part of the SPI burst mode read
operation. See the SPI Read Operation and the SPI Read
Operation in Burst Mode sections for more details.
TEMPERATURE SENSOR
The ADE7903 contains a temperature sensor that is multiplexed
with the V2P input of the voltage channel. Bit 3 (TEMP_EN) of
the CONFIG register selects what the third ADC of the
ADE7903 measures. If the TEMP_EN bit is 0, its default value,
the ADC measures the voltage between the V2P and VM pins.
If the TEMP_EN bit is 1, the ADC measures the temperature
sensor. In the ADE7903, the conversion result is stored in the
V2WV register. The time it takes for the temperature sensor
measurement to settle after the TEMP_EN bit is set to 1 is 5 ms.
The expression used to calculate the temperature in the
microcontroller, when Bit 7 (BW) in the CONFIG register is set
to the default value of 0, is
temp =
8.72101 × 10−5 × (V2WV + TEMPOS × 211) − 306.47
where temp is the temperature value measured in degrees Celsius.
The gain value is different depending on the value of Bit 7 (BW)
in the CONFIG register. When Bit 7 (BW) is set to 0, the gain
used to convert the bit information provided by the ADE7903 into
degrees Celsius has a default value of 8.72101 × 10−5°C/LSB;
when Bit 7 (BW) is set to 1, this gain value is 9.26171 × 10−5°C/LSB.
The temperature measurement accuracy is ±5°C. TEMPOS is the
8-bit, signed, read-only register in which the temperature sensor
offset is stored. The offset information is calculated during the
manufacturing process, and it is stored with the opposite sign.
For example, if the offset is 5, −5 is written into the ADE7903.
One LSB of the TEMPOS register is equivalent to 211 LSBs of the
V2WV register.
Instead of using the default gain value, the gain can be
calibrated as part of the overall meter calibration process.
Measure the temperature, TEMP, of the ADE7903, read the
V2WV register containing the temperature sensor reading of
the ADE7903, and compute the gain as follows:
11
22 ×+
=TEMPOSWVV
TEMP
gaineTemperatur
(6)
+LFSR
GENERATOR
a71 a48 a47 a24 a23 a0
07
815
1623
IWV REGIST ER
0 78 1516 23
07
8151623
V1WV REGISTERV2WV REGISTER
0 78 1516 23
07
8151623
0 78 1516 23
12458-026
b0
LFSR
FB
g0g1g2g15
b1
g3
b2b15
a71
,
a70
,....,
a2
,
a1
,
a0
12458-027
Rev. 0 | Page 16 of 28
Data Sheet ADE7903
PROTECTING THE INTEGRITY OF CONFIGURATION
REGISTERS
The configuration registers of the ADE7903 are either user
accessible registers (CONFIG, SYNC_SNAP, COUNTER0, and
COUNTER1) or internal registers. The internal registers are not
user accessible, and they must remain at their default values. To
protect the integrity of all configuration registers, a write
protection mechanism is available.
By default, the write protection is disabled and the user accessible
configuration registers can be written without restriction. When
the protection is enabled, no writes to any configuration register
are allowed. The registers can always be read, without restriction,
independent of the write protection state.
To enable the protection, write 0xCA to the 8-bit lock register
(Address 0xA). To disable the protection, write 0x9C to the
8-bit lock register. It is recommended that the write protection
be enabled after the CONFIG register is initialized. If any user
accessible register must be changed, for example, during the
synchronization process of multiple ADE7912/ADE7913 and
ADE7903 devices, disable the protection, change the value of
the register, and then reenable the protection.
CRC OF CONFIGURATION REGISTERS
Every output cycle, the ADE7903 computes the CRC of the
CONFIG and TEMPOS registers, as well as Bit 2 (IC_PROT) of
the STATUS0 register, and Bit 7 of the STATUS1 register. The
CRC algorithm is called CRC-16-CCITT. The 16-bit result is
written in the CTRL_CRC register.
The input registers to the CRC circuit form a 64-bit array that is
introduced bit by bit into an LFSR-based generator, similar to
Figure 26 and Figure 27, one byte at a time, least significant byte
first. Each byte is then processed with the MSB first.
The formulas that govern the LFSR are as follows:
bi(0) = 1, where i = 0, 1, 2, …, 15, the initial state of the bits that
form the CRC. Bit b0 is the LSB, and Bit b15 is the MSB.
gi, where i = 0, 1, 2, …, 15 are the coefficients of the generating
polynomial defined by the CRC-16-CCITT algorithm in
Equation 1 and Equation 2.
FB(j) = aj − 1 XOR b15(j − 1) (7)
b0(j) = FB(j) AND g0 (8)
bi(j) = FB(j) AND gi XOR bi − 1(j − 1), i = 1, 2, 3, … , 15 (9)
Equation 7, Equation 8, and Equation 9 must be repeated for
j = 1, 2, … , 64. The value written into the CTRL_CRC register
contains Bit bi(64), i = 0, 1, …, 15. Because each ADE7903 has a
particular TEMPOS register value, each ADE7903 has a different
CTRL_CRC register default value.
ADE7903 STATUS
The bits in the STATUS0 and STATUS1 registers of the ADE7903
characterize the state of the device.
If the value of the CTRL_CRC register changes, Bit 1 (CRC_STAT)
in the STATUS0 register is set to 1. This bit clears to 0 when the
STATUS0 register is read.
After the configuration registers are protected by writing 0xCA
into the lock register, Bit 2 (IC_PROT) in the STATUS0 register
is set to 1. It clears to 0 when the STATUS0 register is read, and
it is set back to 1 at the next ADC output cycle.
At power-up, or after a hardware or software reset, the
ADE7903 signals the end of the reset period by clearing Bit 0
(RESET_ON) in the STATUS0 register to 0.
If the ADC output values of IWV, V1WV, and V2WV are not
read during an output cycle, Bit 3 (ADC_NA) in the STATUS1
register becomes 1. It clears to 0 when the STATUS1 register is
read.
The STATUS0 and STATUS1 registers can be read by executing
an SPI register read. STATUS0 can also be read as part of the
SPI burst mode read operation. See the SPI Read Operation and
the SPI Read Operation in Burst Mode sections for more
information.
Rev. 0 | Page 17 of 28
ADE7903 Data Sheet
Rev. 0 | Page 18 of 28
APPLICATIONS INFORMATION
ADE7903 IN POLYPHASE ENERGY METERS
The ADE7903 is designed for use in a 3-phase energy metering
systems in which three ADE7912/ADE7913 devices and one
ADE7903 device are managed by a master device containing an
SPI interface, usually a microcontroller.
Figure 28. Neutral Line with the ADE7903
Figure 28 shows how the ADE7903 inputs are connected on the
neutral line of a 3-phase system. The neutral current is sensed
using a shunt, and the voltage across the shunt is measured at
the fully differential inputs, IP and IM.
A pole of the shunt is connected to the IM pin of the ADE7903
and becomes the ground, GND. Pin V1P and Pin VM are
connected to the IM pin if they are not in use. The V1P and
V2P voltage channels are used to measure auxiliary voltages. If
V1P or V2P is not used, connect it to VM.
Figure 29 shows a block diagram of a 3-phase energy meter that
uses three ADE7912/ADE7913 devices, one ADE7903 on the
neutral line, and a microcontroller. One 4.096 MHz crystal
provides the clock to the ADE7912/ADE7913 that senses the
Phase A current and voltage. The ADE7912/ADE7913 devices
that sense the Phase B and Phase C currents and voltages and
the ADE7903 device that senses the neutral current are clocked
by a signal generated at the CLKOUT/DREADY pin of the
ADE7912/ADE7913 that is placed to sense the Phase A current
and voltage. As an alternative configuration, the microcontroller
can generate a 4.096 MHz clock to all ADE7912/ADE7913 and
ADE7903 devices at the XTAL1 pin (see Figure 30). Note that
the XTAL1 pin can receive a clock with a frequency within the
3.6 MHz to 4.21 MHz range, as specified in Table 1.
The microcontroller uses the SPI port to communicate with the
ADE7912/ADE7913 and ADE7903 devices. Four of its input/
output pins, CS_A, CS_B, CS_C, and CS_N, are used to generate
the SPI CS signals. The SCLK, MOSI, and MISO pins of the
microcontroller are directly connected to the corresponding
SCLK, MOSI, and MISO pins of each ADE7912/ADE7913
device (see Figure 31). To simplify Figure 29 to Figure 31, these
connections are not shown.
Figure 29. 3-Phase Energy Meter Using Three ADE7912/ADE7913 Devices and
One ADE7903 Device
NEUTRAL
NEUTRAL LINE
ADE7903
IP
IM
V1P
VM
GND
I
N
V2P
12458-028
CS_A
CS_B
CS_C
CS_N
SCLK
MOSI
MISO
I/O
MICROCONTROLLER
NEUTRAL
PHASE C
ISOLATION
BARRIER
PHASE A
PHASE B
PHASE A
ADE7912/ADE7913
PHASE B
ADE7912/ADE7913
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_A
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_B
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
IP
IM
V1P
VM
V2P
GND
MCU
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
LOAD
PHASE C
ADE7912/ADE7913
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_C
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
4.096MHz
CRYSTAL
CLKOUT/
DREADY
CLKOUT/
DREADY
CLKOUT/
DREADY
CLKOUT/
DREADY
PHASE N
ADE7903
12458-029
Data Sheet ADE7903
Rev. 0 | Page 19 of 28
Figure 30. Microcontroller Generating Clock to Three ADE7912/ADE7913
Devices and One ADE7903 Device
In Figure 30, the CLKOUT/DREADY pin of the ADE7912/
ADE7913 used to sense the Phase C current and voltage is
connected to the input/output pin of the microcontroller.
CLKOUT/DREADY provides an active low pulse for 64 CLKIN
cycles (15.625 μs at CLKIN = 4.096 MHz) when the ADC
conversion data is available. It signals when the ADC outputs of
all ADE7912/ADE7913 and ADE7903 devices become available
and when the microcontroller starts to read them. See the
Synchronizing Multiple ADE7912/ADE7913 and ADE7903
Devices section for more information about synchronizing
multiple ADE7912/ADE7913 and ADE7903 devices.
At power-up, or after a hardware or software reset, follow the
procedure described in the Power-Up Procedure for Systems
with Multiple Devices Using a Single Crystal section or the
Power-Up Procedure for Systems with Multiple Devices Using
Clock Generated from Microcontroller section to ensure that
the ADE7912/ADE7913 and ADE7903 devices function
appropriately.
Figure 31. SPI Connections Between Three ADE7912/ADE7913 Devices, One
ADE7903 Device, and a Microcontroller
ADE7903 IN SINGLE-PHASE ENERGY METERS
The ADE7903 is also designed for use in a single-phase energy
metering system in which one ADE7903 device or an ADE7903
and ADE7912/ADE7913 combination is managed by a master
device containing an SPI interface, usually a microcontroller.
Figure 32 shows a block diagram of a single-phase energy meter
that uses an ADE7903 on the phase and a microcontroller. One
4.096 MHz crystal provides the clock to the ADE7903 that senses
the phase current and voltage. Unlike the isolated solution, this
setup means that the ADE7903 is floating at the line voltage.
Other combinations of the ADE7903 and the ADE7912/ADE7913
are possible in a single-phase application for monitoring both
the phase and the neutral.
Figure 32. Single-Phase Energy Meter Using an ADE7903 Device
CLK
CS_A
CS_B
CS_C
CS_N
SCLK
MOSI
I/O
MISO
MICROCONTROLLER
NEUTRAL
PHASE C
ISOLATION
BARRIER
PHASE A
PHASE B
PHASE A
ADE7912/ADE7913
PHASE B
ADE7912/ADE7913
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_A
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_B
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
IP
IM
V1P
VM
V2P
GND
MCU
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
LOAD
PHASE C
ADE7912/ADE7913
IP
IM
V1P
VM
V2P
GND
MCU
GND
ISO_C
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
CLKOUT/
DREADY
CLKOUT/
DREADY
CLKOUT/
DREADY
CLKOUT/
DREADY
PHASE N
ADE7903
12458-030
ADE7912/
ADE7913
PHASE A
ADE7912/
ADE7913
PHASE B
ADE7912/
ADE7913
PHASE C
SCLK
MOSI
MISO
SCLK
MOSI
MISO
SCLK
MOSI
MISO
CS_A
CS_B
SCLK
MOSI
MISO
CS_C
MICROCONTROLLER
CS
CS
CS
10kΩ
VDD
ADE7903
NEUTRAL
SCLK
MOSI
MISO
CS
CS_N
12458-031
CS
SCLK
MOSI
MISO
I/O
MICROCONTROLLER
NEUTRAL
PHASE
IP
IM
V1P
VM
V2P
GND
MCU
XTAL2
XTAL1
SCLK
MOSI
MISO
CS
LOAD
4.096MHz
CRYSTAL
CLKOUT/
DREADY
PHASE
ADE7903
12458-032
ADE7903 Data Sheet
ADE7903 CLOCK
Provide a digital clock signal at the XTAL1 pin to clock the
ADE7903. The frequency at which the ADE7903 is clocked at
XTAL1 is called CLKIN. The ADE7903 is specified for CLKIN =
4.096 MHz, but frequencies between 3.6 MHz and 4.21 MHz are
acceptable.
Alternatively, a 4.096 MHz crystal with a typical drive level of
0.5 mW and an ESR of 20 Ω can be connected across the
XTAL1 and XTAL2 pins to provide a clock source for the
ADE7903 (see Figure 33).
The total capacitance (TC) at the XTAL1 and XTAL2 pins is
TC = C1 + CP1 = C2 + CP2
where:
C1 and C2 are the ceramic capacitors between XTAL1 and GND
and between XTAL2 and GND, respectively.
CP1 and CP2 are the parasitic capacitors of the wires
connecting the crystal to the ADE7903.
The load capacitance (LC) of the crystal is equal to half the total
capacitance because it is the capacitance of the series circuit
composed by C1 + CP1 and C2 + CP2.
222
TCCP2C2CP1C1
LC =
+
=
+
=
Therefore, the value of the C1 and C2 capacitors as a function of
the load capacitance of the crystal is
C1 = C2 = 2 × LC − CP1 = 2 × LC − CP2
In the case of the ADE7903, the typical total capacitance of the
XTAL1 and XTAL2 pins is 40 pF (see Table 1). Select a crystal
with a load capacitance of
pF20
2== TC
LC
Assuming that the parasitic capacitances, CP1 and CP2, are
equal to 20 pF, select the C1 and C2 capacitors equal to 20 pF.
Figure 33. Crystal Circuitry
SPI-COMPATIBLE INTERFACE
The SPI of the ADE7903 is the slave of the communication and
consists of four pins: SCLK, MOSI, MISO, and CS. The serial
clock for a data transfer is applied at the SCLK logic input. All
data transfer operations synchronize to the serial clock. Data
shifts into the ADE7903 at the MOSI logic input on the falling
edge of SCLK, and the ADE7903 samples the data on the rising
edge of SCLK. Data shifts out of the ADE7903 at the MISO
logic output on the falling edge of SCLK and can be sampled by
the master device on the rising edge of SCLK. The MSB of the
word is shifted in and out first. The maximum and minimum
serial clock frequencies supported by this interface are 5.6 MHz
and 250 kHz, respectively. MISO stays in high impedance when
no data is transmitted from the ADE7903. At power-up or
during hardware or software reset, the microcontroller reads the
STATUS0 register to detect when Bit 0 (RESET_ON) clears to 0.
See Figure 31 for details of the connections between the SPI
ports of three ADE7912/ADE7913 devices and one ADE7903
device, and a microcontroller containing an SPI interface.
The CS logic input is the chip select input. Drive the CS input
low for the entire data transfer operation. Bringing CS high
during a data transfer operation leaves the ADE7903 register
that is the object of the data transfer unaffected; however, it
aborts the transfer and places the serial bus in a high impedance
state. A new transfer can then be initiated by returning the CS
logic input to low.
SPI Read Operation
The read operation using the ADE7903 SPI interface is initiated
when the master sets the CS pin low and begins sending one
command byte on the MOSI line. The master places data on the
MOSI line starting with the first high to low transition of SCLK.
The bit composition of the command byte is shown in Table 7.
Bits[1:0] are don’t care bits, and they can have any value. The
examples presented throughout this section show them set to
00. Bit 2 (READ_EN) determines the type of the operation. For
a read, READ_EN must be set to 1. For a write, READ_EN
must be cleared to 0. Bits[7:3] (ADDR) represent the address of
the register to be read or written.
Table 7. Command Byte for SPI Read/Write Operations
Bit Location Bit Name Description
1:0 Reserved These bits can have any value.
2 READ_EN Set this bit to 1 if a SPI read
operation is executed. Clear this
bit to 0 if a SPI write operation is
executed.
7:3
ADDR
Address of the register to be read
or written.
ADE7903
XTAL1
XTAL2
C1
C2
CP1
CP2
TC
TC
12458-033
Rev. 0 | Page 20 of 28
Data Sheet ADE7903
The ADE7903 SPI samples data on the low to high transitions
of SCLK. After the ADE7903 device receives the last bit of the
command byte on a low to high transition of SCLK, it begins to
transmit its contents on the MISO line when the next SCLK high to
low transition occurs; thus, the master can sample the data on a
low to high SCLK transition. After the master receives the last
bit, it sets the CS and SCLK lines high and the communication
ends. The data lines, MOSI and MISO, go into a high impedance
state. Figure 34 shows an 8-bit register read operation; 16-bit
and 32-bit registers are read in the same manner.
Figure 34. SPI Read Operation of an 8-Bit Register
SPI Read Operation in Burst Mode
All ADE7903 output registers (I W V, V 1 W V, V 2 W V,
ADC_CRC, STATUS0, and CNT_SNAPSHOT) can be read in
one of two ways: one register at a time (see the SPI Read
Operation section) or by reading multiple consecutive registers
simultaneously in burst mode. Burst mode is initiated when the
master sets the CS pin low and begins sending the command
byte (see Table 7) on the MOSI line with Bits[7:3] (ADDR) set
to the IWV register address, 00000. This means a command
byte set to 0x04. The master places data on the MOSI line
starting with the first high to low transition of SCLK. The SPI of
the ADE7903 samples data on the low to high transitions of
SCLK. After the ADE7903 device receives the last bit of the
command byte on a low to high transition of SCLK, it begins to
transmit the 24-bit IWV register on the MISO line when the
next SCLK high to low transition occurs; thus, the master can
sample the data on a low to high SCLK transition. After the
master receives the last bit of the IWV register, the ADE7903
device sends V1WV, which is placed at the next location, and
continues in this manner until the master sets the CS and SCLK
lines high and the communication ends. The data lines, MOSI
and MISO, go into a high impedance state. See Figure 35 for
details of the SPI read operation in burst mode.
If a register does not need to be read, for example, the 16-bit
CNT_SNAPSHOT register, the master sets the CS and SCLK
lines high after the STATUS0 register is received.
For example, if the IWV register is not required, but V1WV is,
set the ADDR bits to the V1WV address, 00001, in the
command byte, and execute the burst mode operation.
Figure 35. SPI Read Operation in Burst Mode
SPI Write Operation
The SPI write operation is initiated when the master sets the CS
pin low and begins sending one command byte (see Table 7).
Bit 2 (READ_EN) must be cleared to 0. The master places data
on the MOSI line starting with the first high to low transition of
SCLK. The SPI of the ADE7903 samples data on the low to high
transitions of SCLK. Next, the master sends the 8-bit value of
the register without losing any SCLK cycles. After the last bit is
transmitted, at the end of the SCLK cycle, the master sets the CS
and SCLK lines high, and the communication ends. The data
lines, MOSI and MISO, go into a high impedance state. See
Figure 36 for details of the SPI write operation.
Figure 36. SPI Write Operation
Note that the SPI write operation can execute 8-bit writes only. The
16-bit synchronization counter register (composed of
COUNTER0 and COUNTER1) is written by executing the
write operation twice: the least significant byte is written first,
followed by the most significant byte. See the Synchronizing
Multiple ADE7912/ADE7913 and ADE7903 Devices section for
details on the functionality controlled by the synchronization
counter register.
Because the ADE7903 does not need to acknowledge a write
command in any way, this operation can be broadcast to multiple
ADE7912/ADE7913 and ADE7903 devices when the same
register must be initialized with the same value.
After executing a write operation, it is recommended to read
back the register to ensure that it was initialized correctly.
0
7 6 1 0
REGISTER V ALUE
SCLK
MOSI
CS
MISO
1 0
ADDR[4:0]
12458-034
SCLK
MOSI
CS
MISO
10 00 0 0 00
IWV
CNT_SNAPSHOT
23 015 0
12458-035
SCLK
MOSI
CS
7 6 1 0
REGISTER V ALUE
00 0
ADDR[4:0]
12458-036
Rev. 0 | Page 21 of 28
ADE7903 Data Sheet
SYNCHRONIZING MULTIPLE ADE7912/ADE7913
AND ADE7903 DEVICES
The ADE7912/ADE7913 and ADE7903 allow the user to
sample all currents and voltages simultaneously and to provide
coherent ADC output samples, which is a highly desired feature
in polyphase metering systems.
The ADE7903 in Polyphase Energy Meters section describes
how a polyphase energy meter containing multiple ADE7912/
ADE7913 and ADE7903 devices can use one crystal to clock all
the ADE7912/ADE7913 and ADE7903 devices. At power-up, only
one ADE7912/ADE7913 or ADE7903 device is clocked from the
crystal, while the other devices are set to receive the clock from
the CLKOUT/DREADY pin of the first ADE7912/ADE7913
device. This pin has DREADY functionality enabled by default.
In Figure 29 and Figure 30, the ADE7912/ADE7913 device on
Phase A is clocked from the crystal or the microcontroller, and the
CLKOUT/DREADY pin generates the DREADY signal. The
other ADE7912/ ADE7913 and ADE7903 devices are clocked
by the DREADY signal because the CLKOUT signal has not yet
been received by their XTAL1 pins. The microcontroller enables
CLKOUT functionality when Bit 0 (CLKOUT_EN) in the
CONFIG register is set to 1. This operation ensures that the other
ADE7912/ ADE7913 and ADE7903 devices in the system receive
the same clock as the ADE7912/ADE7913 on Phase A and that
all ADCs within all ADE7912/ADE7913 and ADE7903 devices
in the system sample data at the same exact moment.
As an alternative to using one crystal, the microcontroller can
generate a clock signal to the XTAL1 pins of every ADE7912/
ADE7913 and ADE7903, ensuring precise ADC sampling
synchronization (see Figure 30).
To configure all ADE7912/ADE7913 and ADE7903 devices in
an energy meter to provide coherent ADC output samples, that
is, samples obtained in the same output cycle, all ADE7912/
ADE7913 and ADE7903 devices must have the same ADC
output frequency and the outputs must be synchronized.
Bits[5:4] (ADC_FREQ) in the CONFIG register select the ADC
output frequency; therefore, they must be initialized to the same
value (see the ADC Output Values section for more details).
To synchronize the ADC outputs, that is, to set all ADE7912/
ADE7913 and ADE7903 devices to generate ADC outputs at the
same exact moment, after power-up, the microcontroller must
broadcast a write to the 8-bit SYNC_SNAP register with the
value 0x01. All ADE7912/ADE7913 and ADE7903 devices then
start a new ADC output period simultaneously when Bit 0 (sync)
of the SYNC_SNAP register is written. The sync bit clears itself
to 0 after one CLKIN cycle.
As shown in Figure 29 and Figure 30, the CLKOUT/ DREADY
pin of one ADE7912/ADE7913 or ADE7903 is connected to an
I/O input of the microcontroller. This ADE7912/ADE7913 or
ADE7903 device has Bit 0 (CLKOUT_EN) in the CONFIG
register set to the default value, 0, to enable the DREADY
functionality. When the ADC output period starts, the
CLKOUT/DREADY pin goes low for 64 CLKIN cycles (15.625 µs
when CLKIN = 4.096 MHz), signaling that all ADC outputs
from all ADE7912/ADE7913 and ADE7903 devices are
available and the microcontroller must start reading them. It is
recommended that the SPI read in burst mode be used to
ensure that all data is read in the shortest amount of time.
For more information on the synchronization procedure of
ADE7912/ADE7913 devices, refer to the ADE7912/ADE7913
data sheet. The same synchronization procedure applies to the
ADE7903.
Rev. 0 | Page 22 of 28
Data Sheet ADE7903
POWER MANAGEMENT
POWER-UP AND INITIALIZATION PROCEDURES
At power-up or after a hardware or software reset, execute the
following steps for a microcontroller managing a system formed
by one or multiple ADE7912/ADE7913 and ADE7903 devices.
Power-Up Procedure for Systems with a Single ADE7903
For a standalone ADE7903 device managed by a microcontroller,
the power-up procedure is as follows (see Figure 37):
1. Connect a crystal between the XTAL1 and XTAL2 pins.
2. Supply VDD to the ADE7903 device. To ensure that the
ADE7903 device starts functioning correctly, the supply must
reach 3.3 V − 10% in fewer than 23 ms from approximately
a 2.6 V level. The ADE7903 device starts to function.
3. To determine when the ADE7903 device is ready to accept
commands, read the STATUS0 register until Bit 0
(RESET_ON) is cleared to 0, which happens approximately
20 ms after the ADE7903 starts to function and indicates that
the ADE7903 is fully functional using the default settings.
4. Initialize the CONFIG register.
5. Protect the user accessible and internal configuration
registers by setting the lock register to 0xCA. See the
Protecting the Integrity of Configuration Registers section.
6. When the ADC conversion data is available, the ADE7903
device begins generating a signal that is active low at the
CLKOUT/DREADY pin for 64 CLKIN cycles (15.625 µs
for CLKIN = 4.096 MHz). The DREADY functionality is
enabled by default at the CLKOUT/DREADY pin.
7. The microcontroller reads the IW V, V1W V, V 2W V,
ADC_CRC, CNT_SNAPSHOT, and STATUS0 registers in
SPI burst mode (see the SPI Read Operation in Burst Mode
section for more information).
Note that this power-up procedure also applies in the same way
to systems that have multiple ADE7903 devices, each clocked
from its own crystal. Every ADE7903 device is powered up and
started independently.
Figure 37. Power-Up Procedure for Systems with One or Multiple ADE7903 and ADE7912/ADE7913 Devices, Each Clocked from Its Own Crystal
ADE7912/ADE7913
POWERE D UP
3.3V – 10%
≈2.6V
ADE7903 AND
ADE7912/ADE7913
START
FUNCTIONING
BIT ST ATUS0[ 0]
(RESET_ON)
CLE ARED TO 0
DC-T O-DC CO NV E RTER
POWERE D UP AND
Σ-Δ MODULATORS
FUNCTIONAL
(ADE7912/ADE7913 O NLY)
0V
POR TIMER
TURNE D O N
ADE7903 AND
ADE7912/ADE7913
NONISOLATED
SIDE RE ADY
ADE7912/ADE7913
ISOLATED
SIDE RE ADY
23ms 100ms
20ms
12458-037
Rev. 0 | Page 23 of 28
ADE7903 Data Sheet
Power-Up Procedure for Systems with Multiple Devices
Using a Single Crystal
For polyphase energy meters using the ADE7912/ADE7913 and
ADE7903 devices, shown in Figure 29 and Figure 30, in which a
single crystal is used, see the ADE7912/ADE7913 data sheet for
additional details on the power-up procedure.
Power-Up Procedure for Systems with Multiple Devices
Using Clock Generated from Microcontroller
For polyphase energy meters in which the microcontroller
generates the clock signal used by all ADE7912/ADE7913 and
ADE7903 devices (see Figure 30), see the ADE7912/ADE7913
data sheet for additional details on the power-up procedure.
HARDWARE RESET
The ADE7903 does not have a dedicated reset pin. Instead,
while the SCLK pin is receiving the serial clock, the CS and
MOSI pins can be kept low by executing a SPI broadcast write
operation in which the lines are kept low for 64 SCLK cycles.
This is equivalent to sending eight bytes equal to 0x00 to the
ADE7903 to accomplish a hardware reset.
During a hardware reset, all the registers are set to their default
values. This procedure can be done simultaneously for an
ADE7903 device in a polyphase or single-phase energy meter.
At the end of the reset period, the ADE7903 clears Bit 0
(RESET_ON) in the STATUS0 register to 0. At this point, follow
one of the procedures described in the Power-Up and Initialization
Procedures section to initialize the ADE7903 correctly.
SOFTWARE RESET
Bit 6 (SWRST) in the CONFIG register manages the software
reset functionality. The default value of this bit is 0. If this bit is
set to 1, the ADE7903 enters the software reset state. In this
state, all the internal registers are reset to their default values.
When the software reset ends, Bit 6 (SWRST) in the CONFIG
register clears automatically to 0, and Bit 0 (RESET_ON) in the
STATUS0 register is cleared to 0. If the configuration registers
are protected using a lock = 0xCA register write, first unlock the
registers by writing lock = 0x9C, and then write to the CONFIG
register by setting Bit 6 (SWRST) to 1 to start a software reset.
At this point, follow one of the procedures described in the
Power-Up and Initialization Procedures section to initialize the
ADE7903 correctly.
POWER-DOWN MODE
If the microcontroller generates the clock to all ADE7912/
ADE7913 and ADE7903 devices (see Figure 30), the current
consumption can be reduced by shutting down the clock. The
ADE7903 stops functioning. When the clock is restarted, as a
good programming practice, execute a hardware reset to restart
the ADE7903.
In systems in which the CLKOUT/DREADY pin of one ADE7912/
ADE7913 device is used to clock other ADE7912/ADE7913 and
ADE7903 devices (see Figure 29 and Figure 30), lower current
consumption of the ADE7903 device can be achieved by clearing
Bit 0 (CLKOUT_EN) in the CONFIG register to 0.
Rev. 0 | Page 24 of 28
Data Sheet ADE7903
LAYOUT GUIDELINES
Figure 18 shows the test circuit of the ADE7903. The test circuit
contains three ADE7912/ADE7913 devices and one ADE7903
device together with the surrounding circuitry required to sense
the phase current and voltages in a 3-phase system. The ADE7912/
ADE7913 and ADE7903 devices are managed by a microcontroller
using the SPI interface. The microcontroller is not shown in the
schematic. For the layout of that schematic, refer to the Layout
Guidelines section of the ADE7912/ADE7913 data sheet, in
addition to the guidelines in this section for the ADE7903 on
the neutral channel.
Figure 38 and Figure 39 show a proposed layout of the printed
circuit board (PCB) with two layers that have the components
placed on the top layer of the board only. Follow these layout
guidelines to create a low noise design.
Figure 38. 2-Layer Circuit Board, Top Layer
Figure 39. 2-Layer Circuit Board, Bottom Layer
ADE7903 EVALUATION BOARD
The E VA L -ADE7903EBZ evaluation board allows users to
quickly evaluate the ADE7903. This evaluation board is used in
conjunction with the E VA L -SDP-CB1Z system demonstration
platform. Order both the EVA L -ADE7903EBZ evaluation board
and the system demonstration platform to evaluate the ADE7903.
See the EVA L -ADE7903EBZ product page for details.
ADE7903 VERSION
Bits[2:0] (Version) in the STATUS1 register identify the version
of the ADE7903.
12458-038
12458-039
Rev. 0 | Page 25 of 28
ADE7903 Data Sheet
REGISTER LIST
In Table 8 to Table 14, R means a register can be read, and W means a register can be written. U means an unsigned register, and S means
a signed register in twos complement format.
Table 8. Register List
Address Register Name R/W Bit Length Type Default Value1 Description
0x0
IWV
R
24
S
0x000000
Instantaneous value of Current I.
0x1 V1WV R 24 S 0x000000 Instantaneous value of Voltage V1.
0x2 V2WV R 24 S 0x000000 Instantaneous value of Voltage V2.
0x3 Reserved R 24 S 0x000000 Reserved. This location always reads 0x000000.
0x4 ADC_CRC R 16 U N/A CRC value of IWV, V1WV, and V2WV registers. See the CRC of
ADC Output Values section for details.
0x5 CTRL_CRC R 16 U N/A CRC value of configuration registers. See the CRC of
Configuration Registers section for details.
0x6 Reserved R 16 S 0x0000 Reserved. This location always reads 0x0000.
0x7 CNT_SNAPSHOT R 16 U 0x00 Snapshot value of the counter used in synchronization
operation. See Table 9 and the Synchronizing Multiple
ADE7912/ADE7913 and ADE7903 Devices section for details.
0x8 CONFIG R/W 8 U 0 Configuration register. See Table 10 for details.
0x9 STATUS0 R 8 U 0x01 Status register. See Table 11 for details.
0xA Lock W 8 U 0x00 Memory protection register. See the Protecting the Integrity
of Configuration Registers section and Table 12 for details.
0xB SYNC_SNAP W 8 U 0x00 Synchronization register. See Table 13 for details.
0xC COUNTER0 R/W 8 U N/A Contains the eight LSBs of the internal synchronization
counter.
0xD COUNTER1 R/W 8 U N/A COUNTER1[3:0] bits contain the four MSBs of the internal
synchronization counter. See the Synchronizing Multiple
ADE7912/ADE7913 and ADE7903 Devices section for details.
0xE
Reserved
R/W
8
U
0xFF
Reserved registers.
0xF STATUS1 R 8 U 0x00 Status register. See Table 14 for details.
0x10, 0x11 Reserved R/W 8 U 0x00 For proper operation, do not write to these registers.
0x12, 0x13 Reserved R 8 U 0x00 Reserved registers.
0x14 Reserved No functionality assigned at this address.
0x15, 0x16,
0x17
Reserved R 8 U 0x00 Reserved registers.
0x18 TEMPOS R 8 S N/A Temperature sensor offset. See the Temperature Sensor
section for more information.
1 N/A means not applicable.
Table 9. CNT_SNAPSHOT Register (Address 0x7)
Bit(s) Name Default Value Description
[11:0] Counter 0x000 Snapshot value of the counter used in synchronization operation.
[15:12] Reserved 0000 Reserved. These bits do not represent any functionality.
Rev. 0 | Page 26 of 28
Data Sheet ADE7903
Table 10. CONFIG Register (Address 0x8)
Bit(s) Name Default Value Description
0 CLKOUT_EN 0 Enables CLKOUT functionality at the CLKOUT/DREADY pin. When CLKOUT_EN = 0, the default
value, DREADY functionality is enabled. When CLKOUT_EN = 1, CLKOUT functionality is enabled.
1 Reserved 0 Reserved. This bit does not represent any functionality.
2 Reserved 0 Reserved bit.
3 TEMP_EN 0 This bit selects the second voltage channel measurement. When the TEMP_EN bit is set to 0, the
default value, the voltage between the V2P and VM pins is measured. When this bit is 1, the internal
temperature sensor is measured (see the Temperature Sensor section for more information).
[5:4] ADC_FREQ 00 These bits select the ADC output frequency.
00 = 8 kHz, 125 µs period.
01 = 4 kHz, 250 µs period.
10 = 2 kHz, 500 µs period.
11 = 1 kHz, 1 ms period.
6 SWRST 0 When this bit is set to 1, a software reset is initiated. This bit clears itself to 0 after one CLKIN cycle.
7 BW 0 Selects the bandwidth of the digital low-pass filter of the ADC. When BW = 0, the default value, the
bandwidth is 3.3 kHz. When BW = 1, the bandwidth is 2 kHz. The bandwidth data is for CLKIN =
4.096 MHz and an ADC output frequency of 8 kHz. See the Analog-to-Digital Conversion section for
details on how CLKIN and the ADC output frequency influence the bandwidth selection.
Table 11. STATUS0 Register (Address 0x9)
Bit(s)
Name
Default Value
Description
0 RESET_ON 1 During reset, the RESET_ON bit is set to 1. When the reset ends and the ADE7903 is ready to be
configured, the RESET_ON bit is cleared to 0.
1 CRC_STAT 0 If the CRC of the configuration registers changes value, the CRC_STAT bit is set to 1.
2 IC_PROT 0 If the configuration registers are not protected, this bit is 0. After the configuration registers are
protected (lock register = 0xCA), this bit is set to 1.
[7:3] Reserved 0 Reserved. These bits do not represent any functionality.
Table 12. Lock Register (Address 0xA)
Bit(s) Name Default Value Description
[7:0] LOCK_KEY 00000000 When the LOCK_KEY bits are equal to 0xCA, protection of the configuration registers is enabled.
When the LOCK_KEY bits are equal to 0x9C, the protection is disabled, and the configuration registers
can be written. This is a write only register. If the address location is read, the value is 0x00.
Table 13. SYNC_SNAP Register (Address 0xB)
Bit(s) Name Default Value Description
0 Sync 0 When the sync bit is set to 1 via a broadcast SPI write operation, the ADE7912/ADE7913 devices in the
system generate ADC outputs in the same exact moment. The bit clears itself back to 0 after one CLKIN
cycle. See the Synchronizing Multiple ADE7912/ADE7913 and ADE7903 Devices section for more details.
1 Snap 0 When snap is set to 1 via a broadcast SPI write operation, the internal counters of the ADE7912/ADE7913
devices in the system are latched. The bit clears itself back to 0 after one CLKIN cycle. See the
Synchronizing Multiple ADE7912/ADE7913 and ADE7903 Devices section for more details.
[7:2] Reserved 0 Reserved. These bits do not represent any functionality.
Table 14. STATUS1 Register (Address 0xF)
Bit(s) Name Default Value Description
[2:0]
Version
0
The ADE7903 version number.
3 ADC_NA 0 If the ADC outputs are not accessed during one ADC output period, the ADC_NA bit is set to 1. When
the STATUS1 register is read, the bit is cleared to 0.
[6:4] Reserved 0 Reserved. These bits do not represent any functionality.
7 Reserved 0 Reserved. Internal functionality is associated with this bit.
Rev. 0 | Page 27 of 28
ADE7903 Data Sheet
OUTLINE DIMENSIONS
Figure 40. 20-Lead Standard Small Outline Package, [SOIC_W]
Wide Body
(RW-20)
Dimensions shown in millimeters (and inches)
ORDERING GUIDE
Model1, 2 Temperature Range Package Description Package Option
ADE7903ARWZ −40°C to +85°C 20-Lead Standard Small Outline Package [SOIC_W] RW-20
ADE7903ARWZ-RL −40°C to +85°C 20-Lead Standard Small Outline Package [SOIC_W], 13” Tape and Reel RW-20
EVAL-ADE7903EBZ Evaluation Board
EVAL-SDP-CB1Z Evaluation System Controller Board
1 Z = RoHS Compliant Part.
2 The EVAL-SDP-CB1Z is the controller board that manages the EVAL-ADE7903EBZ evaluation board. Both boards must be ordered together.
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDS MS-013-AC
13.00 (0.5118)
12.60 (0.4961)
0.30 (0.0118)
0.10 (0.0039)
2.65 (0.1043)
2.35 (0.0925)
10.65 (0.4193)
10.00 (0.3937)
7.60 (0.2992)
7.40 (0.2913)
0.75 (0.0295)
0.25 (0.0098)
45°
1.27 (0.0500)
0.40 (0.0157)
COPLANARITY
0.10 0.33 (0.0130)
0.20 (0.0079)
0.51 (0.0201)
0.31 (0.0122)
SEATING
PLANE
8°
0°
20 11
10
1
1.27
(0.0500)
BSC
06-07-2006-A
©2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D12458-0-12/14(0)
Rev. 0 | Page 28 of 28