Methods for protecting outputs of low-voltage circuits from high programming voltages

摘要

A method for isolating a first low-voltage circuit node comprising an output of a low-voltage device from a second circuit node which carries high programming voltages during programming of user-programmable interconnect elements includes the step of raising the normal power supply voltage provided to the low-voltage devices to an intermediate level lower than the programming voltage but high enough to protect the outputs of the low voltage devices from damage. The output to be protected is caused to assume a desired state and is then inhibited from changing state during the programming cycle. Programming voltage is then applied to the low voltage circuit node.