16-Bit, Isolated, Sigma-Delta Modulator

The ADuM7702 is a high performance, second-order, Σ-Δ modulator that converts an analog input signal to a high speed, single-bit data stream, with on-chip digital isolation based on Analog Devices, Inc., iCoupler® technology. The device operates from a 4.5 V to 5.5 V power supply range (VDD1) and accepts a pseudo differential input signal of ±50 mV (±64 mV full-scale). The pseudo 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 21 MHz. The original information can be reconstructed with an appropriate sinc3 digital filter to achieve an 82 dB signal-to-noise ratio (SNR) at 78.1 kSPS with a 256 decimation rate and a 20 MHz main clock. The serial input and output operates from 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, results in on-chip isolation providing outstanding performance characteristics, superior to alternatives such as optocoupler devices. The ADuM7702 is available in both a 16-lead SOICW and an 8-lead SOICIC and has an operating temperature range of −40°C to +125°C.

Applications

* Shunt current monitoring

* AC motor controls

* Power and solar inverters

* Wind turbine inverters

* Analog-to-digital and optoisolator replacement

* 5 MHz to 21 MHz main clock input frequency

* Offset drift vs. temperature: ±0.25 μV/°C

* SNR: 82 dB typical

* 16 bits, no missing codes

* Full-scale analog input voltage range: ±64 mV

* ENOB: 13 bits typical

* IDD1: 10 mA maximum

* On-board digital isolator

* Operating temperature range: −40°C to +125°C

* High isolation common-mode transient immunity: 150 kV/μs minimum, VDD2 = 3.3 V