The ISOSD61 is a galvanic isolated second order Sigma-Delta modulator based on embedded transformer coupling technology. It converts an analog input signal with maximum range of ±320 mV into a high speed, 25 Msps, 1-bit digital data stream. The signal information can be rebuilt by means of a digital filtering. The modulator is isolated from the digital I/O section through a high-speed isolated data coupling, whose performances are far better than other isolated transceivers like optocouplers.