SLVUBQ1A August   2020  – May 2021 TPS543620


  1.   Trademarks
  2. 1Introduction
    1. 1.1 Background
    2. 1.2 Before You Begin
    3. 1.3 Performance Characteristics Summary
  3. 2Configurations and Modifications
    1. 2.1 Output Voltage
    2. 2.2 Switching Frequency (FSEL Pin)
    3. 2.3 Current Limit, Soft-Start Time, and Internal Compensation (MODE Pin)
    4. 2.4 Adjustable UVLO
  4. 3Test Setup and Results
    1. 3.1  Input/Output Connections
    2. 3.2  Efficiency
    3. 3.3  Output Voltage Regulation
    4. 3.4  Load Transient and Loop Response
    5. 3.5  Output Voltage Ripple
    6. 3.6  Input Voltage Ripple
    7. 3.7  Synchronizing to a Clock
    8. 3.8  Start-up and Shutdown with EN
    9. 3.9  Start-up and Shutdown with VIN
    10. 3.10 Start-up Into Pre-Bias
    11. 3.11 Hiccup Current Limit
    12. 3.12 Overvoltage Protection
    13. 3.13 Thermal Performance
  5. 4Board Layout
    1. 4.1 Layout
  6. 5Schematic and Bill of Materials
    1. 5.1 Schematic
    2. 5.2 Bill of Materials
  7. 6Revision History

Start-up and Shutdown with EN

Figure 3-26 and Figure 3-27 show the start-up and shutdown waveforms for U2 with EN. In Figure 3-26, the input voltage is initially applied and the output is inhibited by pulling EN to GND using an external function generator. When the EN voltage is increased above the enable-threshold voltage, the start-up sequence begins and the output voltage ramps up to the externally set value. In Figure 3-27, the external function generator pulls EN to ground and the TPS543620 shuts down.

Figure 3-28 shows EN start-up with a 0.2-Ω resistor load. Figure 3-29 shows the BP5 internal LDO start-up relative to the EN pin.

A shunt on the ENOFF_U1 jumper or RDIV_VIN can be used to test the EN start-up of U1 and U2, respectively. When the shunt is removed from ENOFF_U1, EN is released and the start-up sequence begins for U1. When the shunt is placed on RDIV_VIN, EN is pulled to the input voltage through the resistor divider and the start-up sequence begins for U2.

GUID-E32A178E-FC77-49A5-9DA0-1D812A65FB5A-low.gifFigure 3-26 U2 Start-up with EN – No Load
GUID-5AC0FD15-9BB7-4E51-B283-B928D0165B02-low.gifFigure 3-28 U2 Start-up with EN – 0.2-Ω Load
GUID-C15251CE-9475-4699-B5D8-C0673CAF0858-low.gifFigure 3-27 U2 Shutdown with EN – No Load
GUID-11254670-1F64-434A-8789-10DB77F73C8E-low.gifFigure 3-29 U2 Startup with EN – No Load and Measuring BP5