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PDF ADE7768 Data sheet ( Hoja de datos )
| Número de pieza | ADE7768 | |
| Descripción | Energy Metering IC | |
| Fabricantes | Analog Devices | |
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Energy Metering IC with Integrated
Oscillator and Positive Power Accumulation
ADE7768
FEATURES
On-chip oscillator as clock source
High accuracy, supports 50 Hz/60 Hz IEC62053-21
Less than 0.1% error over a dynamic range of 500 to 1
Supplies positive-only average real power on frequency
outputs F1 and F2
High frequency output CF calibrates and supplies
instantaneous, positive-only real power
Logic output REVP indicates potential miswiring or negative
power
Direct drive for electromechanical counters and 2-phase
stepper motors (F1 and F2)
Proprietary ADCs and DSPs provide high accuracy over
large variations in environmental conditions and time
On-chip power supply monitoring
On-chip creep protection (no-load threshold)
On-chip reference 2.45 V (20 ppm/°C typical) with
external overdrive capability
Single 5 V supply, low power (20 mW typical)
Low cost CMOS process
GENERAL DESCRIPTION
The ADE77681 is a high accuracy, electrical energy metering IC.
It is a pin reduction version of the ADE7755, enhanced with a
precise oscillator circuit that serves as a clock source to the chip.
The ADE7768 eliminates the cost of an external crystal or
resonator, thus reducing the overall cost of a meter built with
this IC. The chip directly interfaces with the shunt resistor.
1U.S. Patents 5,745,323; 5,760,617; 5,862,069; 5,872,469; others pending.
The ADE7768 specifications surpass the accuracy require-
ments of the IEC62053-21 standard. The AN-679 Application
Note can be used as a basis for a description of an IEC61036
(equivalent to IEC62053-21) low cost, watt-hour meter
reference design.
The only analog circuitry used in the ADE7768 is in the Σ-Δ
ADCs and reference circuit. All other signal processing, such as
multiplication and filtering, is carried out in the digital domain.
This approach provides superior stability and accuracy over
time and extreme environmental conditions.
The ADE7768 supplies positive-only average real power
information on the low frequency outputs, F1 and F2. These
outputs can be used to directly drive an electromechanical
counter or interface with an MCU. The high frequency CF logic
output, ideal for calibration purposes, provides instantaneous
positive-only, real power information.
The ADE7768 includes a power supply monitoring circuit on
the VDD supply pin. The ADE7768 remains inactive until the
supply voltage on VDD reaches approximately 4 V. If the supply
falls below 4 V, the ADE7768 also remains inactive and the F1,
F2, and CF outputs are in their nonactive modes.
Internal phase matching circuitry ensures that the voltage and
current channels are phase matched, while the HPF in the
current channel eliminates dc offsets. An internal no-load
threshold ensures that the ADE7768 does not exhibit creep
when no load is present. When REVP is logic high, the
ADE7768 does not generate any pulse on F1, F2, and CF.
The ADE7768 comes in a 16-lead, narrow body SOIC package.
V2P 2
V2N 3
V1N 4
V1P 5
FUNCTIONAL BLOCK DIAGRAM
VDD
1
AGND
6
POWER
SUPPLY MONITOR
+ Σ-Δ ...110101...
ADC
ADE7768
DGND
13
MULTIPLIER
SIGNAL
PROCESSING
BLOCK
+
2.5V
REFERENCE
Σ-Δ
ADC
4kΩ
...11011001...
PHASE
CORRECTION
Φ
HPF
LPF
INTERNAL
OSCILLATOR
DIGITAL-TO-FREQUENCY
CONVERTER
7
REFIN/OUT
11
RCLKIN
8 10 9 12 14 16 15
SCF S0 S1 REVP CF F1 F2
Figure 1.
Rev. A
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
www.analog.com
Fax: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved.
1 page  
ABSOLUTE MAXIMUM RATINGS
TA = 25°C, unless otherwise noted.
Table 3.
Parameter
VDD to AGND
VDD to DGND
Analog Input Voltage to AGND,
V1P, V1N, V2P, and V2N
Reference Input Voltage to AGND
Digital Input Voltage to DGND
Digital Output Voltage to DGND
Operating Temperature Range
Storage Temperature Range
Junction Temperature
16-Lead Plastic SOIC, Power Dissipation
θJA Thermal Impedance1
Package Temperature Soldering
1 JEDEC 1S standard (2-layer) board data.
Value
−0.3 V to +7 V
−0.3 V to +7 V
−6 V to +6 V
−0.3 V to VDD + 0.3 V
−0.3 V to VDD + 0.3 V
−0.3 V to VDD + 0.3 V
−40°C to +85°C
−65°C to +150°C
150°C
350 mW
124.9°C/W
See J-STD-20
ADE7768
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at these or
any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degrada-
tion or loss of functionality.
Rev. A | Page 5 of 20
5 Page 
Nonsinusoidal Voltage and Current
The real power calculation method also holds true for non-
sinusoidal current and voltage waveforms. All voltage and
current waveforms in practical applications have some
harmonic content. Using the Fourier transform, instantaneous
voltage and current waveforms can be expressed in terms of
their harmonic content.
( )∞
v(t) = V0 + 2 × ∑Vh × sin hωt + αh
h≠0
(2)
where:
v(t) is the instantaneous voltage.
V0 is the average value.
Vh is the rms value of voltage harmonic h.
αh is the phase angle of the voltage harmonic.
i(t) = IO +
2
×
∞
∑Ih
×
sin(hω t
+
βh
)
h≠o
(3)
where:
i(t) is the instantaneous current.
I0 is the dc component.
Ih is the rms value of current harmonic h.
βh is the phase angle of the current harmonic.
Using Equations 2 and 3, the real power (P) can be expressed in
terms of its fundamental real power (P1) and harmonic real
power (PH) as P = P1 + PH
where:
P1 = V1 × I1 cos φ1
(4)
φ1 = α1 − β1
and
∞
PH = ∑Vh × Ih cos φh
h≠1
(5)
φh = αh − βh
In Equation 5, a harmonic real power component is generated
for every harmonic, provided that harmonic is present in both
the voltage and current waveforms. The power factor calcul-
ation has previously been shown to be accurate in a pure
sinusoid. Therefore, the harmonic real power must also
correctly account for the power factor, because it is made up
of a series of pure sinusoids.
Note that the input bandwidth of the analog inputs is 7 kHz at
the nominal internal oscillator frequency of 450 kHz.
ADE7768
ANALOG INPUTS
Channel V1 (Current Channel)
The voltage output from the current sensor is connected to the
ADE7768 here. Channel V1 is a fully differential voltage input.
V1P is the positive input with respect to V1N.
The maximum peak differential signal on Channel V1 should
be less than ±30 mV (21 mV rms for a pure sinusoidal signal)
for specified operation.
V1
+30mV
VCM
DIFFERENTIAL INPUT
±30mV MAX PEAK
COMMON-MODE
±6.25mV MAX
V1P
V1 V1N
VCM
–30mV
AGND
Figure 18. Maximum Signal Levels, Channel V1
Figure 18 shows the maximum signal levels on V1P and V1N.
The maximum differential voltage is ±30 mV. The differential
voltage signal on the inputs must be referenced to a common
mode, such as AGND. The maximum common-mode signal is
±6.25 mV.
Channel V2 (Voltage Channel)
The output of the line voltage sensor is connected to the device
at this analog input. Channel V2 is a fully differential voltage
input with a maximum peak differential signal of ±165 mV.
Figure 19 shows the maximum signal levels that can be
connected to the ADE7768 Channel V2.
V2
+165mV
VCM
DIFFERENTIAL INPUT
±165mV MAX PEAK
COMMON-MODE
±25mV MAX
V2P
V2 V2N
VCM
–165mV
AGND
Figure 19. Maximum Signal Levels, Channel V2
Channel V2 is usually driven from a common-mode voltage,
that is, the differential voltage signal on the input is referenced
to a common mode (usually AGND). The analog inputs of the
ADE7768 can be driven with common-mode voltages of up to
25 mV with respect to AGND. However, best results are
achieved using a common mode equal to AGND.
Rev. A | Page 11 of 20
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet ADE7768.PDF ] | |
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