ADE7759_15 Datasheet, PDF (1/36 Pages) Analog Devices – Active Energy Metering IC with di/dt Sensor Interface

a
Active Energy Metering IC with
di/dt Sensor Interface
ADE7759^*
FEATURES
High Accuracy, Supports IEC 687/1036
On-Chip Digital Integrator Allows Direct Interface with
Current Sensors with di/dt Output Such as Rogowski Coil
Less Than 0.1% Error over a Dynamic Range of 1000 to 1
On-Chip User-Programmable Threshold for Line Voltage
SAG Detection and PSU Supervisory
Supplies Sampled Waveform Data and Active Energy
(40 Bits)
Digital Power, Phase, and Input DC Offset Calibration
On-Chip Temperature Sensor (Typical 1 LSB/؇C Resolution)
SPI Compatible Serial Interface
Pulse Output with Programmable Frequency
Interrupt Request Pin (IRQ) and IRQ Status Register
Proprietary ADCs and DSP provide High Accuracy over
Large Variations in Environmental Conditions and Time
Reference 2.4 V ؎ 8% (20 ppm/؇C Typical) with External
Overdrive Capability
Single 5 V Supply, Low Power Consumption (25 mW
Typical)
GENERAL DESCRIPTION
The ADE7759 is an accurate active power and energy measure-
ment IC with a serial interface and a pulse output. The ADE7759
incorporates two second-order Σ-∆ ADCs, a digital integrator
(on CH1), reference circuitry, temperature sensor, and all the
signal processing required to perform active power and energy
measurement.
An on-chip digital integrator allows direct interface to di/dt
current sensors such as a Rogowski coil. The digital integrator
eliminates the need for an external analog integrator and pro-
vides excellent long-term stability and precise phase matching
between the current and the voltage channels. The integrator
can be switched off if the ADE7759 is used with conventional
current sensors.
The ADE7759 contains a sampled waveform register and an
active energy register capable of holding at least 11.53 seconds
of accumulated power at full ac load. Data is read from the
ADE7759 via the serial interface. The ADE7759 also provides a
pulse output (CF) with frequency that is proportional to the
active power.
In addition to active power information, the ADE7759 also
provides various system calibration features, i.e., channel offset
correction, phase calibration, and power offset correction. The
part also incorporates a detection circuit for short duration
voltage drop (SAG). The voltage threshold and the duration (in
number of half-line cycles) of the drop 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 line
cycle energy accumulation mode; i.e., the number of half-line
cycles in which the energy accumulation occurs can be con-
trolled. Line cycle energy accumulation enables a faster and
more precise energy accumulation and is especially useful dur-
ing calibration. This signal is also useful for synchronization of
relay switching with a voltage zero crossing.
The interrupt request output is an open drain, active low logic
output. The interrupt status register indicates the nature of the
interrupt, and the interrupt enable register controls which event
produces an output on the IRQ pin. The ADE7759 is available
in a 20-lead SSOP package.
AV_DD
FUNCTIONAL BLOCK DIAGRAM
RESET
DV_DD DGND
ADE7759
V1P
MULTIPLIER
INTEGRATOR MULTIPLIER
ZX
ADC
V1N
dt
LPF2
SAG
HPF1
TEMP
APGAIN[11:0]
SENSOR
PHCAL[7:0]
V2P
ADC
⌽
V2N
APOS[15:0]
DFC
2.4V
4k⍀
REFERENCE
CFNUM[11:0]
CF
REGISTERS AND
CFDEN[11:0]
SERIAL INTERFACE
LPF1
AGND
REF_IN/OUT
*U.S. Patents 5,745,323; 5,760,617; 5,862,069;5,872,469.
REV. A
DIN DOUT SCLK CS IRQ
CLKIN CLKOUT
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