When performing measurements on DC-DC converters using pulse frequency modulation (PFM), proper care must be taken to ensure that the measurements are accurate. Due to the nature of a converter operating in PFM mode, the test setup required to obtain correct measurements differs from the test setup that is normally used to acquire measurements of the device operating in PWM mode. An improper test setup can result in incorrect efficiency measurement data that varies considerably from the data-sheet specifications provided by Texas Instruments.
This application report contains guidelines that can assist the user in acquiring accurate efficiency measurements. An example of measurements taken on the TPS61020 is provided.