SLUU274A May 2007 – January 2022 TPS40193
The TPS40193EVM-001 contains a 49.9-Ω series resistor (R14) 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 R14 through TP12 and TP13. By monitoring the AC injection level at TP13 and the returned AC level at TP14, the power-supply loop response can be determined. Moving Channel A from TP12 to TP6 (COMP) the control-to-output response of the power stage (also referred to as the power stage transfer function) can be directly measured. See Section 3.9xx for a detailed procedure to perform loop response measurements.