ADE7757 Analog Devices, ADE7757 Datasheet - Page 5

• Manufacturer Part Number: ADE7757
• Description: Energy Metering IC with Integrated Oscillator
• Manufacturer: Analog Devices

1
2,3
4, 5
6
7
8
9,10
11
12
13
14
15,16
REV. PrC.
V
V2P, V2N
V1N, V1P
AGND
REF
S C F
S1, S0
RCLKIN
RESERVED
D G N D
C F
F2,F1
DD
IN/OUT
PRELIMINARY TECHNICAL DATA
Power Supply. This pin provides the supply voltage for the circuitry in the ADE7757. The
supply voltage should be maintained at 5 V ± 5% for specified operation. This pin should be
decoupled with a 10 µF capacitor in parallel with a ceramic 100 nF capacitor.
Analog Inputs for Channel V2 (voltage channel). These inputs provide a fully differential
input pair. The maximum differential input voltage is ±165 mV for specified operation. The
maximum signal level at these pins is ±165 mV with respect to AGND. Both inputs have
internal ESD protection circuitry and an overvoltage of ±6 V can also be sustained on these
inputs without risk of permanent damage.
Analog Inputs for Channel V1 (current channel). These inputs are fully differential voltage
inputs with a maximum signal level of ±30 mV with respect to pin V1N for specified opera-
tion. The maximum signal level at this pin is ±165 mV with respect to AGND. Both inputs
have internal ESD protection circuitry and in addition an overvoltage of ±6 V can be sus-
tained on these inputs without risk of permanent damage.
This provides the ground reference for the analog circuitry in the ADE7757, i.e., ADCs and
reference. This pin should be tied to the analog ground plane of the PCB. The analog ground
plane is the ground reference for all analog circuitry, e.g., antialiasing filters, current and
voltage sensors, etc. For accurate noise suppression, the analog ground plane should only be
connected to the digital ground plane at one point. A star ground configuration will help to
keep noisy digital currents away from the analog circuits.
This pin provides access to the on-chip voltage reference. The on-chip reference has a nomi-
nal value of 2.5 V ± 8% and a typical temperature coefficient of 30 ppm/°C. An external
reference source may also be connected at this pin. In either case this pin should be
decoupled to AGND with a 1 µF tantalum capacitor and 100 nF ceramic capacitor.
Select Calibration Frequency. This logic input is used to select the frequency on the calibra-
tion output CF. Table III shows calibration frequencies selection.
These logic inputs are used to select one of four possible frequencies for the digital-to-fre-
quency conversion. With this logic input, designers have greater flexibility when designing an
energy meter. See Selecting a Frequency for an Energy Meter Application.
To enable the internal oscillator as a clock source to the chip, a precise 5 k
connected from this pin to DGND.
Reserved pin. No load should be connected to this pin.
This provides the ground reference for the digital circuitry in the ADE7757, i.e., multiplier,
filters and digital-to-frequency converter. This pin should be tied to the digital ground plane
of the PCB. The digital ground plane is the ground reference for all digital circuitry, e.g.,
counters (mechanical and digital), MCUs and indicator LEDs. For accurate noise suppres-
sion the analog ground plane should only be connected to the digital ground plane at one
point only, e.g., a star ground.
Calibration Frequency Logic Output. The CF logic output provides instantaneous real power
information. This output is intended for calibration purposes. Also see SCF pin description.
Low Frequency Logic Outputs. F1 and F2 supply average real power information. The logic
outputs can be used to directly drive electromechanical counters and two phase stepper mo-
tors. See Transfer Function.
Transfer Function.
Transfer Function.
Transfer Function.
Transfer Function.
Selecting a Frequency for an Energy Meter Application.
Selecting a Frequency for an Energy Meter Application.
Selecting a Frequency for an Energy Meter Application.
Selecting a Frequency for an Energy Meter Application.
– 5 –
REF
IN/OUT
AGND
V2N
V
V2P
V1N
SCF
V1P
DD
1
3
7
8
2
4
5
6
(Not to Scale)
ADE7757
TOP VIEW
10
16
14
15
13
12
11
9
F1
F2
CF
DGND
RESERVED
RCLKIN
S0
S1
resistor must be