16-Bit, Isolated Sigma-Delta Modulator

The AD7403 is a high performance, second-order, Σ-Δ modulator that converts an analog input signal into a high speed, single-bit data stream, with on-chip digital isolation based on Analog Devices, Inc., iCoupler® technology. The AD7403 operates from a 5 V (VDD1) power supply and accepts a differential input signal of ±250 mV (±320 mV full-scale). The differential input is ideally suited to shunt voltage monitoring in high voltage applications where galvanic isolation is required.

The analog input is continuously sampled by a high performance analog modulator, and converted to a ones density digital output stream with a data rate of up to 20 MHz. The original information can be reconstructed with an appropriate digital filter to achieve 88 dB signal to noise ratio (SNR) at 78.1 kSPS. The serial input/output can use a 5 V or a 3 V supply (VDD2).

The serial interface is digitally isolated. High speed complementary metal oxide semiconductor (CMOS) technology, combined with monolithic transformer technology, means the on-chip isolation provides outstanding performance characteristics, superior to alternatives such as optocoupler devices. The AD7403 device is offered in a 16-lead, wide-body SOIC package and has an operating temperature range of −40°C to +125°C. The AD7403-8 device is offered in an 8-lead, wide-body SOIC package and has an operating temperature range of −40°C to +105°C.

Applications

* Shunt current monitoring

* AC motor controls

* Power and solar inverters

* Wind turbine inverters

* Data acquisition systems

* Analog-to-digital and opto-isolator replacements

* 5 MHz to 20 MHz external clock input rate

* 16 bits, no missing codes

* Signal to noise ratio (SNR): 88 dB (typical)

* Effective number of bits (ENOB): 14.2 bits typical

* Offset drift vs. temperature

* AD7403: 1.6 μV/°C typical

* AD7403-8: 2 μV/°C typical

* On-board digital isolator

* On-board reference

* See data sheet for additional features