PCIM: Isolated ΣΔ converter for drives and inverters

Analog Devices is claiming to have industry’s highest accuracy isolated ΣΔ converter for dc and ac current and voltage measurement.

The AD7403 achieves 81dBmin signal-to-noise and distortion ratio (SINAD, at 78ksample/s over -40 to 125°C).

“Higher SINAD enables more accurate current and voltage measurement which improves the performance of motor drives by reducing torque ripple on the motor shaft,” said ADI.

It has a second-order, ΣΔ modulator that converts an analogue input signal into a single-bit data stream with on-chip digital isolation (1,250Vpeak) through on-chip transformers.

Operation is from 5V at the measurement end and it accepts a differential input signal of ±250mV (±320mV full-scale).

The analogue input is continuously sampled and converted to a ones-density bit stream with a data rate of up to 20MHz. The original information can be reconstructed with appropriate digital filtering to achieve 88 dB signal to noise at 78.1ksample/s.

Power on the output (and control) side is 5V or 3V.

It comes in a 16 pin wide-body SOIC.

Applications are expected in motor drives, solar inverters, and wind inverters.

More about ADI motor control.

AD7403 at a glance

5-20MHz external clock

16 bits, no missing codes

Typical offset drift: 1.5μV/°C

On-board digital isolator

On-board reference

True ±320 mV input range

>25 kV/μs common-mode transient immunity

from News http://ift.tt/1mdkQqi

via Yuichun