The TPS549A20EVM-737 contains a 10-Ω series resistor in the feedback loop for loop response analysis.

1. Set up the EVM as described in Section 5 and Figure 5-2.
2. Connect the isolation transformer to the test points marked TP5 and TP8.
3. Connect the input-signal amplitude-measurement probe (channel A) to TP10. Connect the output-signal amplitude-measurement probe (channel B) to TP11.
4. Connect the ground lead of channel A and channel B to TP15.
5. Inject around 20 mV or less signal through the isolation transformer.
6. To measure control-loop gain and phase margin, change the frequency from 100 Hz to 1 MHz using a 10-Hz or less post filter.
7. Disconnect the isolation transformer from the bode-plot test points before making other measurements.
   • Signal injection into feedback can interfere with the accuracy of other measurements.