16-bit Sigma-Delta modulator includes isolation for HV monitoring applications

April 09, 2015 // By Graham Prophet
Analog Devices has posted details of the AD7402, a high performance, second-order, Σ-Δ modulator that converts an analogue input signal into a high speed, single-bit data stream, with on-chip digital isolation based on ADI’s own iCoupler (non-optical) technology.

The AD7402 operates from a 5V (VDD1) power supply and accepts a differential input signal of ±250 mV (±320 mV full scale). The differential input is suited to shunt voltage monitoring in high voltage applications where galvanic isolation is required. The input is continuously sampled by a high performance analogue modulator, and converted to a digital output stream with a data rate of 10 MHz. The original information can be reconstructed with an appropriate digital filter to achieve 87 dB signal to noise ratio (SNR) at 39 ksamples/sec. The serial input/output can use a 5V or a 3.3V supply (VDD2).

The serial interface is digitally isolated. High speed CMOS technology, combined with monolithic transformer technology, means the on-chip isolation provides outstanding performance characteristics, superior to alternatives such as optocoupler devices. The AD7402 comes in an 8-lead wide body SOIC package and has an operating temperature range of −40°C to +105°C; it is priced at $3.05 (1000).

Analog Devices; www.analog.com/en/products/analog-to-digital-converters/precision-adc-10...

next page; safety approvals/applications/ feature list