A high-side load switch is presented for applications that require multiplexing the supply terminal to multiple voltage sources that are different, unknown, and/or dynamic. The design incorporates p-channel switches with adaptive n-well biasing to ensure that no junction is forward biased. Measured results are presented from a circuit that has been fabricated in a standard 0.35 μm CMOS process. The circuit is also demonstrated in an application of programming non-volatile memory.