SLUAA80 November 2020 TPS40322
2.1 Calculation for VOUT Settings
Figure 2-2 shows the FB network circuit.
Figure 2-2 FB Network. Converter DC regulation forces VFB = VREF = 0.6 V. Therefore, the divider is injecting current iINJ into the FB node to offset the output voltage.
- Calculate VOUT as a function of iINJ
KCL at FB node:
Equation 1.
Rearrange and simplify as Equation 2 shows:
Equation 2.
- Solve for iINJEquation 3.
KCL @ X to solve for Vx:
Equation 4.
Rearrange and simplify as Equation 5 shows:
Equation 5.
- Substitute:Equation 6.
where Vx equals Equation 5.
These calculations are integrated in the TPS40322 Resistor Divider Vout Offset Calculator tool.