Interface apparatus with leakage mitigation

Abstract

Aspects of the present disclosure are directed to detecting and powering external circuits via a common port. As may be implemented in accordance with one or more embodiments, an accessory detection circuit detects a type of an external circuit based upon a pull-down resistance at an interface port (e.g., where each accessory type provides a discernable pull-down resistance). Power switching circuitry couples power between the interface port and an internal power-based circuit, and operates in an open condition when the accessory detection circuit is active. An adaptive biasing circuit sets a voltage across the power switching circuitry to about zero, based on a voltage level provided on the interface port, thereby mitigating changes in the pull-down resistance due to current leakage. Once the type of external circuit is identified, the power switching circuitry couples power between the external circuit and the internal circuit.