SLVS350J October 2002 – May 2019 TPS795
The output voltage of the TPS79501 adjustable regulator is programmed using an external resistor divider as shown in Figure 26.
The output voltage is calculated using Equation 1.
Resistors R1 and R2 should be chosen for approximately 40-µA divider current. Lower value resistors can be used for improved noise performance, but the device wastes more power. Higher values should be avoided, as leakage current at FB increases the output voltage error.
The recommended design procedure is to choose R2 = 30.1 kΩ to set the divider current at 40 µA, C1 = 15 pF for stability, and then calculate R1 using Equation 2.
To improve the stability of the adjustable version, TI suggests placing a small compensation capacitor between OUT and FB.
The approximate value of this capacitor can be calculated using Equation 3.
The suggested value of this capacitor for several resistor ratios is shown in the table within Figure 26. If this capacitor is not used (such as in a unity-gain configuration), then the minimum recommended output capacitor is 2.2 µF instead of 1 µF.