Fail-safe and high voltage tolerant test control circuitry for an integrated circuit (ic)

Abstract

An example circuit and an electrical system utilizing test control circuitry to manage the transmission of electrical test signals between an integrated circuit and a main board are provided. The circuit includes test control circuitry configured to selectively transmit electrical test signals between an IC and a pad interface based on a plurality of asynchronous electrical supplies, at least one of which exceeds a maximum voltage rating of the test control circuitry. The test control circuitry includes first and second switching stage circuitry enabling electrical flow through the circuit based on first and second asynchronous electrical supply voltages. Intermediate biasing circuitry further defines an intermediate voltage between the first switching stage circuitry and the second switching stage circuitry. Protective circuitry is configured to ensure a voltage difference across any two terminals of a particular transistor does not exceed a particular maximum voltage rating associated with the particular transistor.