8.2.2.1.3 Input Capacitor Selection

The TPS65295 requires input decoupling capacitors on both power supply input PVIN and PVIN_VPP, and the bulk capacitors are needed depending on the application. The minimum input capacitance required is given in Equation 5.

Equation 5.

TI recommends using a high-quality X5R or X7R input decoupling capacitors of 30 µF on the VDDQ buck input voltage pin PVIN, and 10 µF on the VPP buck input voltage pin PVIN_VPP. The voltage rating on the input capacitor must be greater than the maximum input voltage. The capacitor must also have a ripple current rating greater than the maximum input current ripple of the application. The input ripple current is calculated by Equation 6:

Equation 6.

An additional 0.1-µF capacitor from PVIN to ground and from PVIN_VPP to ground is optional to provide additional high frequency filtering. One ceramic capacitor of 10 µF is recommended for the decoupling capacitor on VLDOIN pin for providing stable power on VTT LDO block. A 1-µF ceramic capacitor is needed for the decoupling capacitor on VCC_5V input.