SLUUBC0A December   2015  – August 2021 TPS548A20

 

  1.   Trademarks
  2. 1 Introduction
  3. 2 Description
    1. 2.1 Typical Applications
    2. 2.2 Features
  4. 3 Electrical Performance Specifications
  5. 4 Schematic
    1. 4.1 8
  6. 5 Test Setup
    1. 5.1 Test Equipment
    2. 5.2 Recommended Test Setup
  7. 6 Configurations
    1. 6.1 Switching Frequency Selection
    2. 6.2 Mode Selection
    3. 6.3 VDD Pin Supply Selection
  8. 7 Test Procedure
    1. 7.1 Line and Load Regulation and Efficiency Measurement Procedure
    2. 7.2 Control-Loop Gain and Phase-Measurement Procedure
    3. 7.3 List of Test Points
    4. 7.4 Equipment Shutdown
  9. 8 EVM Assembly Drawing and PCB Layout
  10. 9 Bill of Materials
  11. 10Revision History

7.2 Control-Loop Gain and Phase-Measurement Procedure

The TPS548A20EVM-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.