a
Energy Metering IC
with Pulse Output
ADE7755*
The ADE7755 is a high accuracy electrical energy measurement
IC. The part specifications surpass the accuracy requirements as
quoted in the IEC1036 standard. See Analog Devices’ Application Note AN-559 for a description of an IEC1036 watt-hour
meter reference design based on the AD7755.
FEATURES
High Accuracy, Surpasses 50 Hz/60 Hz IEC 687/1036
Less than 0.1% Error over a Dynamic Range of
500 to 1
The ADE7755 Supplies Average Real Power on the
Frequency Outputs F1 and F2
The High-Frequency Output CF Is Intended for
Calibration and Supplies Instantaneous Real Power
Pin Compatible with AD7755 with Synchronous CF and
F1/F2 Outputs
The Logic Output REVP Can Be Used to Indicate a
Potential Miswiring or Negative Power
Direct Drive for Electromechanical Counters and
Two Phase Stepper Motors (F1 and F2)
A PGA in the Current Channel Allows the Use of Small
Values of Shunt and Burden Resistance
Proprietary ADCs and DSP 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 2.5 V ؎ 8% (30 ppm/؇C Typical)
with External Overdrive Capability
Single 5 V Supply, Low Power (15 mW Typical)
Low Cost CMOS Process
The only analog circuitry used in the ADE7755 is in the ADCs
and reference circuit. All other signal processing (e.g., multiplication and filtering) is carried out in the digital domain. This
approach provides superior stability and accuracy over extremes
in environmental conditions and over time.
The ADE7755 supplies average real power information on the
low-frequency outputs F1 and F2. These logic outputs may be
used to directly drive an electromechanical counter or interface
to an MCU. The CF logic output gives instantaneous real power
information. This output is intended to be used for calibration
purposes or for interfacing to an MCU.
The ADE7755 includes a power supply monitoring circuit on the
AVDD supply pin. The ADE7755 will remain in a reset condition
until the supply voltage on AVDD reaches 4 V. If the supply falls
below 4 V, the ADE7755 will also be reset and no pulses will be
issued on F1, F2, and CF.
Internal phase matching circuitry ensures that the voltage and
current channels are phase matched whether the HPF in Channel 1 is on or off. An internal no-load threshold ensures that the
ADE7755 does not exhibit any creep when there is no load.
GENERAL DESCRIPTION
The ADE7755 is available in a 24-lead SSOP package.
The ADE7755 is pin compatible with the AD7755. The only
difference between the ADE7755 and the AD7755 is that the
ADE7755 features a synchronous CF and F1/F2 outputs under
all load conditions.
FUNCTIONAL BLOCK DIAGRAM
AVDD
G0 G1
AGND
AC/DC
DVDD
DGND
ADE7755
POWER
SUPPLY MONITOR
V1P
V1N
ADC
SIGNAL
PROCESSING
BLOCK
PHASE
CORRECTION
...110101...
PGA
؋1, ؋2, ؋8, ؋16
⌽
HPF
LPF
MULTIPLIER
V2P
V2N
ADC
...11011001...
DIGITAL-TO-FREQUENCY
CONVERTER
4k⍀
2.5V
REFERENCE
REFIN/OUT
CLKIN CLKOUT SCF S0
S1 REVP CF
F1
RESET
F2
*U.S. Patents 5,745,323, 5,760,617, 5,862,069, and 5,872,469.
REV. 0
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: 781/329-4700
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2002
