SLUU254A December   2006  – January 2022 TPS40075

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Description
    2. 1.2 Applications
    3. 1.3 Features
  3. 2TPS40075EVM-001 Electrical Performance Specifications
  4. 3Schematic
    1. 3.1 Adjusting Output Voltage (R5 and R6)
    2. 3.2 Using Remote Sense (J3)
    3. 3.3 5-V Input Operation (R10 and R15)
    4. 3.4 Enable
  5. 4Test Setup
    1. 4.1 Equipment
      1. 4.1.1 Voltage Source
      2. 4.1.2 Meters
      3. 4.1.3 Loads
        1. 4.1.3.1 LOAD1
      4. 4.1.4 Recommended Wire Gauge
        1. 4.1.4.1 V12V_IN to J1
        2. 4.1.4.2 J2 to LOAD1 (Power)
        3. 4.1.4.3 J3 to LOAD1 (Remote Sense)
      5. 4.1.5 Other
        1. 4.1.5.1 Fan
        2. 4.1.5.2 Oscilloscope
    2. 4.2 Equipment Setup
      1. 4.2.1 Procedure
      2. 4.2.2 Diagram
    3. 4.3 Start-Up/Shutdown Procedure
    4. 4.4 Equipment Shutdown
  6. 5TPS40075EVM Typical Performance Data and Characteristic Curves
  7. 6EVM Assembly Drawings and Layout
  8. 7List of Materials
  9. 8Revision History

3.3 5-V Input Operation (R10 and R15)

Due to higher duty cycles associated with higher output voltages or lower input voltages, output current should be limited to 10 A when operating with output voltages greater than 2.0 V or input voltages below 6 V to reduce conduction losses in the main switching FET (Q1). Under these conditions a lower RDS(on) MOSFET would normally be selected.

To operate with a 5-V input, two resistors need to be changed. R10 (RKFF) sets the voltage ramp amplitude and needs to be reduced to 53.6 kΩ to lower the UVLO to 3.9 V for 5 V operation. In addition, a 330-kΩ resistor should be added at R15 to prevent an internal race condition during soft start.