An electrical connector may have connector contacts. Protection circuitry in the connector may prevent circuit damage. The protection circuitry may include diodes that shunt excessive voltages to ground. The protection circuitry may be implemented in a semiconductor die. The semiconductor die may be embedded within a substrate layer in a printed circuit. The printed circuit may form the body of the connector. Connector contacts may be formed on upper and lower surfaces of the printed circuit. Conductive structures such as vias in the printed circuit may be used to couple semiconductor die contacts on the semiconductor die to the connector contacts. The semiconductor die may be a double-sided die having first and second semiconductor dies that are bonded to each other in a back-to-back configuration.