9.2.2.5 Setting the Output Voltage

When the adjustable output voltage version TPS63050 is used, the output voltage is set by the external resistor divider. The resistor divider must be connected between VOUT, FB and GND. When the output voltage is regulated properly, the typical value of the voltage at the FB pin is 800 mV. The current through the resistive divider must be 100 times greater than the current into the FB pin. The typical current into the FB pin is 0.1 μA, and the voltage across the resistor between FB and GND, R₂, is typically 800 mV. Based on these two values, the recommended value for R2 must be lower than 200 kΩ, in order to set the divider current at 3 μA or higher. It is recommended to keep the value for this resistor in the range of 200 kΩ. The value of the resistor connected between VOUT and FB, R1, depending on the needed output voltage (V_OUT), can be calculated using Equation 7:

Equation 7.

When using the HotRod package version of the TPS63050, it is recommended to add capacitor C₅, as shown in Figure 9. The capacitor on the feedback node is required to help filtering ground noise and matching the efficiency result shown in the Application Curves paragraph.