SLVU888A April 2013 – August 2021 TPS54628
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 5.5 V:
Table 3-1 lists the R1 values for some common output voltages. A feed forward capacitor (C4) can be used to improve phase margin. Feed forward capacitors are most effective for higher output voltages of 1.8 V or above. 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.
| OUTPUT VOLTAGE (V) | R1 (kΩ) | R2 (kΩ) | C4 (pF)(1) | L1 (µH) | C9 + C10 + C11 (µF) | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| MIN | TYP | MAX | MIN | TYP | MAX | MIN | MAX | |||
| 1 | 6.81 | 22.1 | 5 | 150 | 220 | 1.0 | 1.5 | 4.7 | 22 | 68 |
| 1.05 | 8.25 | 22.1 | 5 | 150 | 220 | 1.0 | 1.5 | 4.7 | 22 | 68 |
| 1.2 | 12.7 | 22.1 | 5 | 100 | 1.0 | 1.5 | 4.7 | 22 | 68 | |
| 1.5 | 21.5 | 22.1 | 5 | 68 | 1.0 | 1.5 | 4.7 | 22 | 68 | |
| 1.8 | 30.1 | 22.1 | 5 | 22 | 1.2 | 1.5 | 4.7 | 22 | 68 | |
| 2.5 | 49.9 | 22.1 | 5 | 22 | 1.5 | 2.2 | 4.7 | 22 | 68 | |
| 3.3 | 73.2 | 22.1 | 2 | 22 | 1.8 | 2.2 | 4.7 | 22 | 68 | |
| 5 | 124 | 22.1 | 2 | 22 | 2.2 | 3.3 | 4.7 | 22 | 68 | |