ADE7756_15 Datasheet, PDF (1/32 Pages) Analog Devices – Active Energy Metering IC with Serial Interface

a
Active Energy Metering IC
with Serial Interface
ADE7756*
FEATURES
The ADE7756 contains a sampled Waveform register and an
High Accuracy, Supports IEC 687/1036
Active Energy register capable of holding at least five seconds of
Less than 0.1% Error over a Dynamic Range of 1000 to 1 _{accumulated power at full load. Data is read from the ADE7756}
An On-Chip User Programmable Threshold for Line
via the serial interface. The ADE7756 also provides a pulse output
Voltage SAG Detection and PSU Supervisory
(CF) with a frequency that is proportional to the active power.
The ADE7756 Supplies Sampled Waveform Data
(20 Bits) and Active Energy (40 Bits)
In addition to real power information, the ADE7756 also provides
Digital Power, Phase and Input Offset Calibration
An On-Chip Temperature Sensor (؎3؇C Typical after
Calibration)
An SPI-Compatible Serial Interface
A Pulse Output with Programmable Frequency
An Interrupt Request Pin (IRQ) and Status Register
E _{Provide Early Warning of Register Overflow and}
Other Conditions
Proprietary ADCs and DSP Provide High Accuracy
T ^{over Large Variations in Environmental Conditions}
and Time
Reference 2.4 V ؎ 8% (20 ppm/؇C Typical) with External
Overdrive Capability
E Single 5 V Supply, Low Power (25 mW Typical)
GENERAL DESCRIPTION
L ^{The ADE7756 is a high-accuracy electrical power measurement}
IC with a serial interface and a pulse output. The ADE7756
incorporates two second-order sigma-delta ADCs, reference
circuitry, temperature sensor, and all the signal processing
required to perform active power and energy measurement.
system calibration features, i.e., channel offset correction, phase
calibration, and power calibration. The part also incorporates a
detection circuit for short duration low voltage variations or sags.
The voltage threshold level and the duration (in number of half-
line cycles) of the variation are user programmable. An open drain
logic output (SAG) goes active low when a sag event occurs.
A zero crossing output (ZX) produces an output that is synchro-
nized to the zero crossing point of the line voltage. This output can
be used to extract timing or frequency information from the line.
The signal is also used internally to the chip in the calibration
mode. This permits faster and more accurate calibration of the
real power calculation. This signal is also useful for synchronization
of relay switching with a voltage zero crossing, thus improving
the relay life by reducing the risk of arcing.
The interrupt request output is an open drain, active low logic
output. The IRQ output will become active when the accumu-
lated real power register is half-full and also when the register
overflows. A status register indicates the nature of the interrupt.
The ADE7756 is available in 20-lead DIP and 20-lead
SSOP packages.
O _{FUNCTIONAL BLOCK DIAGRAM}
AV_DD
RESET
DV_{DD DGND}
S _V1P
V1N
B _V2P
O^V2N
PGA
TEMP
SENSOR
ADC
MULTIPLIER ^{HPF1 MULTIPLIER LPF2 ADE7756}
ADC
APGAIN[11:0]
PHCAL[5:0]
⌽
APOS[11:0]
DFC
ZX
SAG
2.4V
4k⍀
REFERENCE
ADE7756 REGISTERS
AND
SERIAL INTERFACE
CF
LPF1
CFDIV[11:0]
AGND
REF_IN/OUT
DIN DOUT SCLK CS IRQ
CLKIN CLKOUT
*U.S. Patents 5,745,323; 5,760,617; 5,862,069; 5,872,469; other pending.
REV. 0
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© Analog Devices, Inc., 2001