SNVU588A December   2017  – January 2022 TPS40345

 

  1.   Trademarks
  2. 1Description
    1. 1.1 Applications
    2. 1.2 Features
  3. 2TPS40345EVM-353 Electrical Performance Specifications
  4. 3TPS40345EVM-353 Schematic
  5. 4Connector and Test Point Descriptions
    1. 4.1 Enable Jumper (JP2)
    2. 4.2 Frequency Spread Spectrum – FSS Jumper (JP1)
    3. 4.3 Test Point Descriptions
      1. 4.3.1 Input Voltage Monitoring (TP1 and TP2)
      2. 4.3.2 Output Voltage Monitoring (TP3 and TP4)
      3. 4.3.3 Loop Response Testing (TP5, TP6, TP7, TP8, and R3)
      4. 4.3.4 Error Amplifier Voltage Monitoring (TP9, TP10, and TP11)
      5. 4.3.5 Switching Waveform Monitoring (TP12, TP13, TP14, and TP15)
      6. 4.3.6 Power-Good Voltage Monitoring (TP16 and TP18)
      7. 4.3.7 Enable and Soft-Start Voltage Monitoring (TP17 and TP18)
  6. 5Test Setup
    1. 5.1 Equipment
      1. 5.1.1 Voltage Source
      2. 5.1.2 Meters
      3. 5.1.3 Load
      4. 5.1.4 Oscilloscope
      5. 5.1.5 Recommended Wire Gauge
      6. 5.1.6 Other
    2. 5.2 Equipment Setup
      1. 5.2.1 Procedure
      2. 5.2.2 Diagram
    3. 5.3 Start-Up/Shutdown Procedure
    4. 5.4 Output Ripple Voltage Measurement Procedure
    5. 5.5 Control Loop Gain and Phase Measurement Procedure
    6. 5.6 Equipment Shutdown
  7. 6TPS40345EVM-353 Test Data
    1. 6.1 Efficiency
    2. 6.2 Line and Load Regulation
    3. 6.3 Output Voltage Ripple
    4. 6.4 Switch Node
    5. 6.5 Control Loop Bode Diagram
    6. 6.6 Additional Waveforms
      1. 6.6.1 Output Ripple With Frequency Spread Spectrum (FSS) Enabled
  8. 7TPS40345EVM-353 Assembly Drawings and Layout
  9. 8TPS40345EVM-353 Bill of Materials
  10. 9Revision History

5.5 Control Loop Gain and Phase Measurement Procedure

  1. Follow Section 5.3 steps 1 – 5 to set VIN and LOAD1 to the desired operating condition:
    1. If JP1 is installed (FSS enabled), loop response data about the modulation frequency (30 kHz) may be affected.
  2. Connect a 1-kHz – 1-MHz isolation transformer to TP5 and TP7 as shown in Figure 5-3.
  3. Connect input signal amplitude measurement probe (channel A) to TP7 as shown in Figure 5-3.
  4. Connect output signal amplitude measurement probe (channel B) to TP5 as shown in Figure 5-3.
  5. Connect ground lead of channel A and channel B to TP6 and TP8 as shown in Figure 5-3.
  6. Inject 30 mV or less signal across R3 through isolation transformer.
  7. Sweep frequency from 1 kHz to 1 MHz with 10-Hz or lower post filter.
  8. Control loop gain can be measured by GUID-8CB81DB9-6126-4434-9BAC-021DA56BE62F-low.gif
  9. Control loop phase can be measured by the phase difference between channel A and channel B.
  10. Control to output response (power stage transfer function) can be measured by connecting channel A probe to TP10 (COMP) and channel B probe to TP5 (CHB).
  11. Output to control response (compensated error amplifier transfer function) can be measured by connecting channel A probe to TP7 (CHA) and channel B probe to TP10 (COMP).
  12. Follow Section 5.3 steps 6 and 7 to power down.