A semiconductor die includes a transformer with terminals of a first winding electrically coupled to external die terminals of the semiconductor die. The terminals of a second winding of the transformer are coupled to internal circuitry of the semiconductor die. An ESD clamp circuit is electrically coupled to the center tap of the second winding of the transformer. When made conductive during and ESD event, the ESD clamp circuit discharges ESD current between the center tap and a supply rail.