SLVU379A August   2010  – August 2021 TPS54521

 

  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
      2. 1.3.2 Slow-Start Time
      3. 1.3.3 Track In
      4. 1.3.4 Adjustable UVLO
      5. 1.3.5 Input Voltage Rails
  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 Hiccup Overcurrent 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

1.3.1 Output Voltage Set Point

The output voltage is set by the resistor divider network of R8 and R9. R9 is fixed at 10 kΩ. To change the output voltage of the EVM, it is necessary to change the value of resistor R8. Changing the value of R8 can change the output voltage above 0.8 V. The value of R8 for a specific output voltage can be calculated using Equation 1.

Equation 1. GUID-B384B2F9-E04E-4ED6-B836-49DB66C7BDB9-low.gif

Table 1-3 lists the R8 values for some common output voltages. Note that VIN must be in a range so that the minimum on-time is greater than 135 ns, and the maximum duty cycle is less than 95%. In addition, different output voltages may require different frequency compensation, which will require changes to the values of R4, C4, C6, and C11. The values given in Table 1-3 are standard values, not the exact value calculated using Equation 1.

Table 1-3 Output Voltages Available
OUTPUT VOLTAGE (V)R8 VALUE (kΩ)
1.812.4
2.521.5
3.331.6
552.3