HI TI people
im using 2 linear regulators one is the TPS7A3001 for negative voltage and the TPS7A4901 for the positive voltage, i have read the datasheet and the user guide(SLVU405–August 2010)in which i find the two equation that you recommend, but i also find a suggestion where you say that chAnge only R2 so we can maintain the frecuency formed by R1 and Cbyo. so my question is which is the value of this frecuency?, or in what range?, i understand that has to be close to zero, im right?.
thanks
Equation 2 in that user's guide tells you where the frequency is. Keeping that frequency the same is a guideline to keep the same transient and start-up performance of the circuit. You can change R1 instead, if you also change Cbyp to keep the frequency the same as set by equation 2. Here is an app note that discusses the feedforward capacitor in more detail: http://focus.ti.com/lit/an/slva289/slva289.pdf