SLUUBE0A November   2015  – August 2021 TPS549A20

 

  1.   Trademarks
  2. Introduction
  3. Description
    1. 2.1 Typical Applications
    2. 2.2 Features
  4. Electrical Performance Specifications
  5. Schematic
  6. Test Setup
    1. 5.1 Test Equipment
    2. 5.2 Recommended Test Setup
  7. Configurations
    1. 6.1 PMBus Address Selection
    2. 6.2 Mode Selection
    3. 6.3 VDD Pin Supply Selection
  8. Test Procedure
    1. 7.1 Line and Load Regulation and Efficiency Measurement Procedure
    2. 7.2 PMBUS Setup and Verification
    3. 7.3 Control-Loop Gain and Phase-Measurement Procedure
    4. 7.4 List of Test Points
    5. 7.5 Equipment Shutdown
  9. EVM Assembly Drawing and PCB Layout
  10. Bill of Materials
  11. 10Revision History

Control-Loop Gain and Phase-Measurement Procedure

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.