The AD7400/AD7401 are 2nd order sigma-delta modulators that convert an analog input signal into a high speed 1-bit data stream with onboard digital isolation based on Analog Devices' iCoupler technology. The AD7400/AD7401 operate from a 5 V power supply and accept a differential input signal of 200 mV. The analog input is continuously sampled by the analog modulator, eliminating the need for external sample and hold circuitr y. The input information is contained in the output stream as a density of ones with data rates up to 20MHz. The original information can be reconstructed with an appropriate digital filter. The serial I/O may use a 5V or 3V supply (VDD2). The serial interface is digitally isolated. High-speed CMOS,