Test selection techniques

摘要

A test selection system is provided which includes a semiconductor substrate (S) having a pin (AX) connected thereto and an integrated circuit (M) disposed on the substrate (S) and connected to the pin (AX) having an operating voltage within a given voltage range. A latch conditioning circuit (12) having an input responsive to a voltage of a given magnitude has an output (NB) connected to a latch (14), and a voltage control circuit (10) operable at a voltage without the given voltage range selectively applies a control voltage of the given magnitude to the input of the latch conditioning circuit (12). A voltage without the given voltage range is applied to the pin (AX) during a first interval of time to produce the control voltage for establishing a test mode and a voltage within the given voltage range is applied to the pin (AX) during a second interval of time to establish a normal operating mode for the integrated circuit (M).