A data coupler includes a transformer having primary and secondary windings, a data transmitter coupled to the primary winding of the transformer, and a data receiver coupled to the secondary winding. The data transmitter includes a first driver and a second driver having outputs coupled to respective ends of the primary winding. The first driver is responsive to a data signal and the second driver is responsive to a delayed version of the data signal, such that the primary winding is supplied with pulses representing a difference between the data signal and the delayed version of the data signal. The data coupler also includes an ac (alternating current) path to ground from the secondary winding for conducting to ground common mode signals coupled to the secondary winding via an inter-winding capacitance of the transformer.