Energy Metering IC with Pulse Output
High Accuracy, Surpasses 50 Hz/60 Hz IEC 687/1036
Less than 0.1% Error over a Dynamic Range of 500 to 1
The SCE7755 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
SCE7755 GENERAL DESCRIPTION
The SCE7755 is pin compatible with the AD7755. The only difference between the SCE7755 and the AD7755 is that the
SCE7755 features a synchronous CF and F1/F2 outputs under all load conditions.
The SCE7755 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.
The only analog circuitry used in the SCE7755 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 SCE7755 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 SCE7755 includes a power supply monitoring circuit on the AVDD supply pin. The SCE7755 will remain in a reset condition
until the supply voltage on AVDD reaches 4 V. If the supply falls below 4 V, the SCE7755 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 SCE7755 does not exhibit any creep when there is no load.
SCE7755 FUNCTIONAL BLOCK DIAGRAM
*U.S. Patents 5,745,323, 5,760,617, 5,862,069, and 5,872,469.
Free Datasheet http://www.datasheet4u.com/