SNVSBI9 October 2019 LMR33610
The output voltage of LMR33610 is externally adjustable using a resistor divider network. The range of recommended output voltage is found in the table. The divider network is comprised of RFBT and RFBB and closes the loop between the output voltage and the converter. The converter regulates the output voltage by holding the voltage on the FB pin equal to the internal reference voltage, VREF. The resistance of the divider is a compromise between excessive noise pickup and excessive loading of the output. Smaller values of resistance reduce noise sensitivity but also reduce the light-load efficiency. The recommended value for RFBT is 100 kΩ with a maximum value of 1 MΩ. If a 1 MΩ is selected for RFBT, then a feedforward capacitor must be used across this resistor to provide adequate loop phase margin (see the CFF Selection section). Once RFBT is selected, use Equation 3 to select RFBB. VREF is nominally 1 V (see the section for limits).
For this 5-V example, RFBT = 100 kΩ and RFBB = 24.9 kΩ are chosen.