JAJSAY9L February 2009 – May 2018 LM26420
The output voltage is set using Equation 1 where R2 is connected between the FB pin and GND, and R1 is connected between VOUT and the FB pin. A good value for R2 is 10 kΩ. When designing a unity gain converter (VOUT = 0.8 V), R1 must be between 0 Ω and 100 Ω, and R2 must be on the order of 5 kΩ to 50 kΩ. 10 kΩ is the suggested value where R1 is the top feedback resistor and R2 is the bottom feedback resistor.
To determine the maximum allowed resistor tolerance, use Equation 3:
VOUT = 2.5 V, with a setpoint accuracy of ±3.5%.
Choose 1% resistors. If R2 = 10 kΩ, then R1 is 21.25 kΩ.