JAJSIO5B July 2019 – February 2020 LMR36506-Q1
ADVANCE INFORMATION for pre-production products; subject to change without notice.
In an adjustable output voltage version, pin 8 of the device is FB. The output voltage of LMR36506-Q1 is externally adjustable using an external resistor divider network. The range of recommended output voltage is found in the . 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. Once RFBT is selected, Equation 2 is used to select RFBB. VREF is nominally 1 V.
For this 5-V example, RFBT = 100 kΩ and RFBB = 24.9 kΩ.