SLVU835A January   2013  – October 2021 TPS54239

 

  1.   Trademarks
  2. 1Introduction
  3. 2Performance Specification Summary
  4. 3Modifications
    1. 3.1 Output Voltage Setpoint
    2. 3.2 Output Filter and Closed-Loop Response
  5. 4Test Setup and Results
    1. 4.1  Input/Output Connections
    2. 4.2  Start-Up Procedure
    3. 4.3  Efficiency
    4. 4.4  Load Regulation
    5. 4.5  Line Regulation
    6. 4.6  Load Transient Response
    7. 4.7  Output Voltage Ripple
    8. 4.8  Input Voltage Ripple
    9. 4.9  Start-Up
    10. 4.10 Shut-Down
  6. 5Board Layout
    1. 5.1 Layout
  7. 6Schematic, Bill of Materials, and Reference
    1. 6.1 Schematic
    2. 6.2 Bill of Materials
    3. 6.3 Reference
  8. 7Revision History

3.1 Output Voltage Setpoint

To change the output voltage of the EVMs, it is necessary to change the value of resistor R1. Changing the value of R1 can change the output voltage above 0.765 V. The value of R1 for a specific output voltage can be calculated using Equation 1.

For output voltage from 0.76 V to 7 V:

Equation 1. GUID-9A1905F7-621C-4C1F-8A45-4D75D47B9192-low.gif

Table 3-1 lists the R1 values for some common output voltages. For higher output voltages of 1.8 V or above, a feedforward capacitor (C4) may be required to improve phase margin. Pads for this component (C4) are provided on the printed-circuit board (PCB). Note that the resistor values given in Table 3-1 are standard values and not the exact value calculated using Equation 1.

Table 3-1 Output Voltages
Output Voltage (V) R1 (kΩ) R2 (kΩ) C4 (pF)(1) L1 (µH) C8 + C9 + C10 (µF)
Min Typ Max Min Typ Max Min Max
1 6.81 22.1 5 150 220 1.5 2.2 4.7 22 68
1.05 8.25 22.1 5 150 220 1.5 2.2 4.7 22 68
1.2 12.7 22.1 5 100 1.5 2.2 4.7 22 68
1.5 21.5 22.1 5 68 1.5 2.2 4.7 22 68
1.8 30.1 22.1 5 22 2.2 3.3 4.7 22 68
2.5 49.9 22.1 5 22 2.2 3.3 4.7 22 68
3.3 73.2 22.1 5 22 2.2 3.3 4.7 22 68
5 124 22.1 5 22 3.3 4.7 22 68
6.5 165 22.1 5 22 3.3 4.7 22 68
(1) Optional