SLVU452A May 2011 – October 2021 TPS54228
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 7.0 V:
Equation 1. 
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. 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) | L1 (µH) | C9. C10, C11 Total Capacitance (µF) |
|---|---|---|---|---|---|
| 1.0 | 6.81 | 22.1 | 1.5 - 2.2 | 22 - 68 | |
| 1.05 | 8.25 | 22.1 | 1.5 - 2.2 | 22 - 68 | |
| 1.2 | 12.7 | 22.1 | 2.2 | 22 - 68 | |
| 1.5 | 21.5 | 22.1 | 2.2 | 22 - 68 | |
| 1.8 | 30.1 | 22.1 | 5 - 22 | 3.3 | 22 - 68 |
| 2.5 | 49.9 | 22.1 | 5 - 22 | 3.3 | 22 - 68 |
| 3.3 | 73.2 | 22.1 | 5 - 22 | 3.3 | 22 - 68 |
| 5.0 | 124 | 22.1 | 5 - 22 | 4.7 | 22 - 68 |
| 6.5 | 165 | 22.1 | 5 - 22 | 4.7 | 22 - 68 |