Isolated Sigma-Delta Modulator Achieves Industry’s Highest Accuracy Measurements


Highest Accuracy Isolated Sigma-Delta Modulator Increases Efficiency of Motor Drives and Power Inverters

The Wall Street Journal, May 22, 2014

Analog Devices, Inc. introduced today the industry’s highest accuracy isolated sigma-delta modulator for precision current and voltage measurement in DC/AC power conversion applications. The AD7403 isolated sigma-delta modulator achieves an 81-dB signal-to-noise and distortion ratio (SINAD) (min) @ 78 KSPS over a -40Cdeg to +125Cdeg temperature range, which is 11 dB higher than competing devices. The higher SINAD enables more accurate current and voltage measurement which improves the performance of motor drives by reducing torque ripple on the motor shaft. The higher SINAD also increases the power transfer efficiency in DC/AC power inverter applications, such as motor drives, solar and wind inverters.

The AD7403 isolated sigma-delta modulator integrates ADI’s iCoupler(R) digital isolation technology, creating a single-chip solution for measuring the voltage across a shunt resistor by converting an analog signal into a 1-bit data stream that can be clocked at up to 20 MHz. The increased isolation working voltage (1250 V peak) allows designers to replace less accurate, more costly Hall Effect sensors in higher DC-bus voltage power conversion and motor drive applications.

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