ADE7759 Datasheet, PDF (1/32 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
The ADE7759 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 measurement
IC with a serial interface and a pulse output. The ADE7759 incor-
porates 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 accumu-
lated 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.
AVDD
FUNCTIONAL BLOCK DIAGRAM
RESET
DVDD DGND
MULTIPLIER
INTEGRATOR MULTIPLIER
ADE7759
ZX
V1P
ADC
V1N
dt
LPF2
SAG
HPF1
TEMP
SENSOR
APGAIN[11:0]
PHCAL[7:0]
APOS[15:0]
V2P
ADC
⌽
V2N
DFC
2.4V
4k⍀
REFERENCE
CFNUM[11:0]
REGISTERS AND
CFDEN[11:0]
CF
SERIAL INTERFACE
LPF1
AGND
REF_IN/OUT
DIN DOUT SCLK CS IRQ
*U.S. Patents 5,745,323; 5,760,617; 5,862,069; 5,872,469; others pending.
REV. 0
CLKIN CLKOUT
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. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
www.analog.com
Fax: [phone]
© Analog Devices, Inc., 2001