ZHCSHA3D NOVEMBER 2009 – March 2018 TPS40303 , TPS40304 , TPS40305
PRODUCTION DATA.
The selection of the output capacitor is typically driven by the output transient response. Equation 21 and Equation 22 overestimate the voltage deviation to account for delays in the loop bandwidth and can be used to determine the required output capacitance.
If VIN(min)> 2 × VOUT, use overshoot (Equation 21) to calculate minimum output capacitance. If VIN(min)< 2 × VOUT, use undershoot (Equation 22) to calculate minimum output capacitance.
With a minimum capacitance, the maximum allowable ESR is determined by the maximum ripple voltage and is approximated by Equation 24.
Two 47-µF and one 220-µF capacitors are selected to provide more than 250 µF of minimum capacitance and 5.2 mΩ of ESR.