A voltage margining circuit is used to trim, scale, or test the output of a power converter. Adjustable power supplies, such as low dropout regulators (LDOs), DC/DC converters, or SMPS provide a feedback (FB) input that is used to control the desired output. A precision smart DAC, such as the DAC53204 or DAC53004, provides linear control of the power supply output when the DAC is supplied and the output is powered on.