ADE7755ARS Analog Devices Inc, ADE7755ARS Datasheet - Page 14

• Manufacturer Part Number: ADE7755ARS
• Description: IC ENERGY METERING 24-SSOP
• Manufacturer: Analog Devices Inc

Specifications of ADE7755ARS

• Rohs Status: RoHS non-compliant
• Input Impedance: 390 KOhm
• Measurement Error: 0.1%
• Voltage - I/o High: 2.4V
• Voltage - I/o Low: 0.8V
• Current - Supply: 3mA
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-SSOP (0.200", 5.30mm Width)
• Meter Type: Single Phase
• For Use With: EVAL-ADE7755ZEB - BOARD EVALUATION FOR AD7755
• Lead Free Status / RoHS Status: Not Compliant

ADE7755
Channel 2 (Voltage Channel)
The output of the line voltage transducer is connected to the
ADE7755 at this analog input. Channel 2 is a fully differential
voltage input. The maximum peak differential signal on Channel 2
is ±660 mV. Figure 25 illustrates the maximum signal levels that
can be connected to Channel 2 of the ADE7755.
Channel 2 must be driven from a common-mode voltage, that
is, the differential voltage signal on the input must be referenced
to a common mode (usually AGND). The analog inputs of the
ADE7755 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.
TYPICAL CONNECTION DIAGRAMS
Figure 26 shows a typical connection diagram for Channel 1. A
current transformer (CT) is the current transducer selected for
this example. Note that the common-mode voltage for Channel 1
is AGND and is derived by center-tapping the burden resistor to
AGND. This provides the complementary analog input signals for
V1P and V1N. The CT turns ratio and burden resistor Rb are
selected to give a peak differential voltage of ±470 mV/gain at
maximum load.
IP
Figure 27 shows two typical connections for Channel 2. The first
option uses a potential transformer (PT) to provide complete
isolation from the power line. In the second option, the ADE7755
is biased around the neutral wire, and a resistor divider provides
a voltage signal that is proportional to the line voltage. Adjusting
the ratio of Ra, Rb, and VR is also a convenient way of carrying
out a gain calibration on the meter.
PHASE
+660mV
–660mV
V
NEUTRAL
CM
V2
Figure 25. Maximum Signal Levels, Channel 2
AGND
Figure 26. Typical Connection for Channel 1
CT
DIFFERENTIAL INPUT
±660mV MAX PEAK
Rb
COMMON-MODE
±100mV MAX
Rf
Rf
±470mV
GAIN
AGND
V2
V
CM
Cf
Cf
V2P
V2N
V1P
V1N
Rev. A | Page 14 of 20
PHASE
PHASE
POWER SUPPLY MONITOR
The ADE7755 contains an on-chip power supply monitor. The
analog supply (AV
If the supply is less than 4 V ± 5%, the ADE7755 resets. This is
useful to ensure correct device startup at power-up and power-
down. The power supply monitor has built-in hysteresis and
filtering. These features give a high degree of immunity to false
triggering due to noisy supplies.
In Figure 28, the trigger level is nominally set at 4 V. The
tolerance on this trigger level is about ±5%. The power supply
and decoupling for the part should be such that the ripple at
AV
operation.
DD
INTERNAL
does not exceed 5 V ± 5%, as specified for normal
NEUTRAL
NEUTRAL
RESET
AV
DD
5V
4V
0V
Figure 27. Typical Connections for Channel 2
Ra
Figure 28. On-Chip Power Supply Monitor
1
RESET
Rb
VR
DD
PT
1
1
1
Ra >> Rb + VR
Rb + VR = Rf
) is continuously monitored by the ADE7755.
±660mV
Cf
AGND
±660mV
ACTIVE
TIME
Rf
Rf
Rf
Cf
Cf
RESET
Cf
V2P
V2N
V2P
V2N