SLUUCK4 November 2021 TPS562212
3.2 Output Voltage Setpoint
The output voltage is set with a resistor divider from the output node to the FB pin. TI recommends using 1% tolerance or better divider resistors. Referring to the application schematic of Figure 6-1, start with 10 kΩ or 20 kΩ for R9 and use Equation 1 to calculate R8. To improve efficiency at light loads, consider using larger value resistors. If the values are too high, the regulator is more susceptible to noise and voltage errors from the FB input current are noticeable.
Table 3-2 lists the R8 and R9 values for some common output voltages. Note that the values given in Table 3-2 are standard values and not the exact value calculated using above equation.
| OUTPUT VOLTAGE(1) (V) | R8(2) (kΩ) | R9 (kΩ) | L1(3) (μH) | COUT(4) (μF) | RANGE of L1·COUT_E(5) (μH × μF) | C7(6) (pF) |
|---|---|---|---|---|---|---|
| 0.76 | 5.36 | 20.0 | 0.68 | 2 × 22 | 17 to 130 | — |
| 1.05 | 15.0 | 20.0 | 1.0 | 2 × 22 | 17 to 130 | 10 to 100 |
| 1.8 | 40.0 | 20.0 | 1.5 | 1 × 22 | 15 to 160 | 10 to 100 |
| 2.5 | 31.6 | 10.0 | 1.8 | 1 × 22 | 15 to 160 | 10 to 100 |
| 3.3 | 45.3 | 10.0 | 2.2 | 1 × 22 | 15 to 160 | 10 to 100 |
| 5 | 73.2 | 10.0 | 3.3 | 1 × 22 | 15 to 160 | 10 to 100 |