SLVU356A January 2010 – October 2021 TPS54290 , TPS54291
The TPS54291EVM-431 contains a 51-Ω series resistor (R13) in the feedback loop to allow for matched impedance signal injection into the feedback for loop response analysis. An isolation transformer should be used to apply a small (30 mV or less) signal across R13 through TP14 and TP16. By monitoring the AC injection level at TP14 and the returned AC level at TP16, the power supply loop response can be determined.