SLVU263A August   2008  – October 2021 TPS54231

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Background
    2. 1.2 Performance Specification Summary
    3. 1.3 Modifications
      1. 1.3.1 Output Voltage Set Point
  3. 2Test Setup and Results
    1. 2.1  Input / Output Connections
    2. 2.2  Efficiency
    3. 2.3  Output Voltage Load Regulation
    4. 2.4  Output Voltage Line Regulation
    5. 2.5  Load Transients
    6. 2.6  Loop Characteristics
    7. 2.7  Output Voltage Ripple
    8. 2.8  Input Voltage Ripple
    9. 2.9  Powering Up
    10. 2.10 Eco-mode Operation
    11. 2.11 Thermal Characteristics
  4. 3Board Layout
    1. 3.1 Layout
    2. 3.2 Estimated Circuit Area
  5. 4Schematic and Bill of Materials
    1. 4.1 Schematic
    2. 4.2 Bill of Materials
  6. 5Revision History

2.9 Powering Up

The start-up waveforms are shown in Figure 2-9 and Figure 2-10. In Figure 2-9, the top trace shows VIN, and the bottom trace shows VOUT. In Figure 2-10 , the top trace shows EN (enable) whereas the bottom trace shows VOUT. In Figure 2-10, the input voltage is initially applied and the output is inhibited by using a jumper at J2 to tie EN to GND. When the jumper is removed, EN is released. When the EN voltage reaches the enable-threshold voltage of 1.25 V, the start-up sequence begins and the internal reference voltage begins to ramp up at the internally set rate toward 0.8 V and the output voltage ramps up to the externally set value of 3.3 V. The input voltage for these plots is 15 V and there is no load.

GUID-51EA2E4F-87C6-46AC-8A12-79D7B634C987-low.png Figure 2-9 TPS54231EVM-372 Start-Up Relative to VIN
Figure 2-10 TPS54231EVM-372 Start-up Relative to Enable