Isolated Sigma-Delta Modulator

The AD7401A is a second-order, sigma-delta (Σ-Δ) modulator that converts an analog input signal into a high speed, 1-bit data stream with on-chip digital isolation based on the Analog Devices, Inc., iCoupler® technology. The AD7401A operates from a 5 V power supply and accepts a pseudo-differential input signal of ±250 mV (±320 mV full scale). The analog input is continuously sampled by the analog modulator, eliminating the need for external sample-and-hold circuitry. The input information is contained in the output stream as a density of ones with a data rate of up to 20 MHz. The original information can be reconstructed with an appropriate digital filter. The serial I/O can use a 5 V or a 3.3 V supply (VDD2).

The serial interface is digitally isolated. High speed CMOS, combined with Analog Devices, Inc., iCoupler® technology, means the on-chip isolation provides outstanding performance characteristics, superior to alternatives such as optocoupler devices. The device contains an on-chip reference. The AD7401A is offered in a 16-lead SOIC and has an operating temperature range of −40°C to +125°C.

Applications

* AC motor controls

* Shunt current monitoring

* Data acquisition systems

* Analog-to-digital and opto-isolator replacements

* 20 MHz maximum external clock rate

* Second-order modulator

* 16 bits, no missing codes

* ±2 LSB INL typical at 16 bits

* 1 µV/°C typical offset drift

* On-board digital isolator

* On-board reference

* ±250 mV analog input range

* Low power operation: 17 mA typical at 5.5 V

* −40°C to +125°C operating range

* 16-lead SOIC package

* Internal clock version: AD7400A

* Safety and regulatory approvals

* UL 1577

* VISO = 5000 V rms for 1 minute

* IEC / CSA 62368-1

* IEC / CSA 61010-1

* DIN EN IEC 60747-17 (VDE 0884-17)

* VIORM = 645 V peak

* Qualified for Automotive Applications