ADE7761BARS-REF AD [Analog Devices], ADE7761BARS-REF Datasheet - Page 11

• Manufacturer Part Number: ADE7761BARS-REF
• Description: Energy Metering IC with On-Chip Fault and Missing Neutral Detection
• Manufacturer: AD [Analog Devices]

THEORY OF OPERATION
POWER SUPPLY MONITOR
The ADE7761B continuously monitors the power supply (V
with its on-chip power supply monitor. If the supply is less than
4 V ± 5%, the ADE7761B goes into an inactive state; that is, no
energy is accumulated, and the CF, F1, and F2 outputs are disabled.
This is useful to ensure correct device operation at power-up
and during power-down. The power supply monitor has built-in
hysteresis and filtering that provide a high degree of immunity
to false triggering due to noisy supplies.
The power supply and decoupling for the part should be such
that the ripple at V
normal operation.
ANALOG INPUTS
Channel V1 (Current Channel)
The voltage outputs from the current transducers are connected
to the ADE7761B at Channel V1. It has two voltage inputs, V
and V
However, at any one time, only one input is selected to perform
the power calculation (see the Fault Detection section).
The maximum peak differential signal on V
is ±660 mV. However, Channel V1 has a programmable gain
amplifier (PGA) with user-selectable gains of 1 and 16 (see
Table 5). This gain facilitates easy transducer interfacing.
Table 5. Channel V1 Dynamic Range
PGA
0
1
Figure 12 shows the maximum signal levels on V
V
the gain selection. The differential voltage signal on the inputs
must be referenced to a common mode (usually AGND).
REVP - FAULT - CF -
1N
F1 - F2 OUTPUTS
. The maximum differential voltage is ±660 mV divided by
ADE7761B
1B
. These inputs are fully differential with respect to V
V
5V
4V
0V
DD
Figure 11. On-Chip, Power Supply Monitoring
Gain
1
16
INACTIVE
DD
does not exceed 5 V ± 5%, as specified for
Maximum Differential Signal (mV)
660
41
ACTIVE
TIME
INACTIVE
1A
− V
1N
1A
and V
, V
1B
, and
1B
− V
1N
DD
Rev. 0 | Page 11 of 24
1A
1N
.
)
Channel V2 (Voltage Channel)
The output of the line voltage transducer is connected to the
ADE7761B at this analog input. Channel V2 is a single-ended
voltage input. The maximum peak differential signal on
Channel V2 is ±660 mV with respect to V
maximum signal levels that can be connected to Channel V2.
The differential voltage V
common mode (usually AGND). The analog inputs of the
ADE7761B can be driven with common-mode voltages of up
to 100 mV with respect to AGND. However, the best results
are achieved using a common mode equal to AGND.
MISCAL Input
The input for the power calibration in missing neutral mode
is connected to the ADE7761B at this analog input. MISCAL
is a single-ended, voltage input. It is recommended to use a dc
signal derived from the voltage reference to drive this pin. The
maximum peak differential signal on MISCAL is 660 mV with
respect to V
can be connected to the MISCAL pin.
The differential voltage, MISCAL − V
to a common mode (usually AGND). The analog inputs of the
ADE7761B can be driven with common-mode voltages of up to
100 mV with respect to AGND. However, best results are achieved
using a common mode equal to AGND.
+660mV + V
–660mV + V
+660mV + V
–660mV
+660mV
GAIN
GAIN
+ V
+ V
V
V
V
CM
CM
CM
CM
V
CM
CM
CM
MISCAL
CM
1A
2N
V2
Figure 12. Maximum Signal Levels, Channel V1
Figure 13. Maximum Signal Levels, Channel V2
, V
. Figure 14 shows the maximum signal levels that
Figure 14. Maximum Signal Levels, MISCAL
1B
COMMON MODE
±100mV MAX
DIFFERENTIAL INPUT A
DIFFERENTIAL INPUT B
2P
±660mV MAX PEAK
±660mV MAX PEAK
DIFFERENTIAL INPUT
DIFFERENTIAL INPUT
±660mV MAX PEAK
− V
±660mV MAX PEAK
AGND
COMMON MODE
COMMON MODE
2N
±100mV MAX
±100mV MAX
must be referenced to a
V
2N
CM
, must be referenced
2N
. Figure 13 shows the
AGND
V1
V1
MISCAL
V
V2
V
CM
MISCAL
CM
ADE7761B
V
V
V
V
V
V
1A
1N
1B
2N
2P
2N