a power supply that is capable of supplying power to an input / output channel for an industrial process control system . the power supply includes a primary voltage converter having a first voltage input and a second voltage output , and overvoltage protection components that prevent the second voltage from rising above a predetermined maximum . the power supply includes a first low dropout regulator that is connected to receive the second voltage and to generate a third voltage , a second low dropout regulator that is connected to receive the second voltage and to generate a fourth voltage , and a third low dropout regulator that is connected to receive the fourth voltage and to generate a fifth voltage . the power supply provides an over - voltage fault tolerant self - testable architecture , allows for compact low cost individual channel isolation and fault tolerant emi / rfi filtration .