ade7761a Analog Devices, Inc., ade7761a Datasheet - Page 11

• Manufacturer Part Number: ade7761a
• Description: Energy Metering Ic With On-chip Fault And Missing Neutral Detection
• Manufacturer: Analog Devices, Inc.

OPERATION
POWER SUPPLY MONITOR
The ADE7761A continuously monitors the power supply (V
with its on-chip, power supply monitor. If the supply is less than
4 V ± 5%, the ADE7761A 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, which provides 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 ADE7761A at Channel V1. It has two voltage inputs, V
and V
However, at any one time, only one is selected to perform the
power calculation (see the Fault Detection section).
The maximum peak differential signal on V
is ±660 mV. However, Channel 1 has a programmable gain
amplifier (PGA) with user-selectable gains of 1 or 16 (see
Table 5). This gain facilitates easy transducer interfacing.
Table 5. Channel 1 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
ADE7761A
1B
. These inputs are fully differential with respect to V
V
DD
5V
4V
0V
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
ADE7761A at this analog input. Channel V2 is a single-ended,
voltage input. The maximum peak differential signal on Channel 2
is ±660 mV with respect to V
signal levels that can be connected to Channel 2.
The differential voltage V
common mode (usually AGND). The analog inputs of the
ADE7761A 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 ADE7761A 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.
+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
, V
Figure 12. Maximum Signal Levels, Channel 1
Figure 13. Maximum Signal Levels, Channel 2
. Figure 14 shows the maximum signal levels that
Figure 14. Maximum Signal Levels, MISCAL
1B
COMMON MODE
±100mV MAX
DIFFERENTIAL INPUT B
DIFFERENTIAL INPUT A
2P
±660mV MAX PEAK
±660mV MAX PEAK
DIFFERENTIAL INPUT
DIFFERENTIAL INPUT
±660mV MAX PEAK
− V
±660mV MAX PEAK
2N
AGND
COMMON MODE
COMMON MODE
. Figure 13 shows the maximum
2N
±100mV MAX
±100mV MAX
must be referenced to a
V
CM
AGND
V1
V1
V
V2
V
MISCAL
MISCAL
CM
CM
ADE7761A
V
V
V
V
V
V
1A
1N
1B
2N
2N
2P