DESCRIPTION

The OSE7751 is a high accuracy fault tolerant electrical energy measurement IC intended for use with two-wire distribution systems. The part specifications surpass the accuracy requirements as quoted in the IEC1036 standard.

The only analog circuitry used on the OSE7751 is in the ADCs and reference circuit. All other signal processing (e.g., multiplication and filter) is carried out in the digital domain. This approach provides superior stability and accuracy over extremes in environmental conditions and over time.

The OSE7751 incorporates a novel fault detection scheme that both warns of fault conditions and allows the OSE7751 to continue accurate billing during a fault event. The OSE7751 does this by continuously monitoring both the phase and neutral (return) currents. A fault is indicated when these currents differ by more than 12.5%. Billing is continued using the larger.

The OSE7751 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.

The OSE7751 includes a power supply monitoring circuit on the AVDD supply pin. The OSE7751 will remain in a reset condition until the supply voltage on AVDD reaches 4 V. If the supply falls below 4 V, the OSE7751 will also be reset and no pulses will be issues on F1, F2 and CF.

Internal phase matching circuitry ensures that the voltage and current channels are matched whether the HPF in Channel 1 is on or off. An internal no-load threshold ensures that the OSE7751 does not exhibit any creep when there is no load.

The OSE7751 is available in 24-lead DIP and SSOP packages.Every piece will be strictly tested.

This chip has been bulk used in India,China, and some other countries for more than 3 years. The first piece of Chinese 7751 IC was from our factory.

Other mark: AT7751, SE1751, FM7751

FEATURES

• High Accuracy, Supports 50 Hz/60 Hz IEC 521/1036 Less than 0.1% Error Over a Dynamic Range of 500 to 1
• The OSE7751 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 Data
• Continuous Monitoring of the Phase and Neutral Current Allows Fault Detection in Two-Wire Distribution Systems
• The OSE7751 Uses the Larger of the Two Currents (Phase or Neutral) to Bill-Even During a Fault Condition
• Two Logic Outputs (FAULT and REVP) Can Be Used to Indicate a Potential Miswiring or Fault Condition
• 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 2.5V±8%(30ppm/℃Typical) with External Overdrive Capability
• Single 5 V Supply, Low Power (13 mW Typical)
• Low Cost CMOS Process

OSE7751 PIN FUNCTION DESCRIPTIONS

DVDD	Digital power supply
AC/DC	High-pass filter select
AVDD	Analog power supply
V1A	Current analog input for channel 1
V1B	Current analog input for channel 2
V1N	Negative input pin for current analog input channel
V2N	Negative input pin for voltage analog input channel
V2P	Positive input pin for voltage analog input channel
RESET	Reset pin for OSE7751
REF	On-chip voltage reference
AGND	Ground reference for analog circuitry
SCF、S1、S0	Select calibration frequency
G1、G0	Select gains for analog current input V1A and VIB
CLKIN	Input pin of clock source
CLKOUT	Output pin of clock source
FAULT	Logic output for fault condition
REVP	Logic output for negative power
DGND	Ground reference for digital circuitry
CF	Calibration frequency logic output
F2、F1	Low frequency logic output pin, can be used