SLVSHP9 July 2026 TPS544A28
PRODUCTION DATA
To calculate the value of the output inductor (LOUT), use Equation 10. The output capacitor filters the inductor-ripple current (IIND(ripple)). Therefore, selecting a high inductor-ripple current impacts the selection of the output capacitor because the output capacitor must have a ripple-current rating equal to or greater than the inductor-ripple current. Larger ripple current increases output ripple voltage, but improves signal-to-noise ratio and helps to stabilize operation. Generally speaking, the inductance value must set the ripple current at approximately 15% to 40% of the maximum output current for a balanced performance.
For this design, the inductor-ripple current is set to 30% of 12A output current. With a 800kHz switching frequency, 16V as maximum VIN, and 3.3V as the output voltage, Based on these parameters, Equation 10 calculates an inductance of 0.91μH. A nearest standard value of 0.91µH is chosen.
The inductor requires a low DCR to achieve good efficiency. The inductor also requires enough room above peak inductor current before saturation. Use Equation 11 to estimate the inductor current ripple. For this design, by tying the CFG1 pin to VCC, IOC(valley) is set to 13A, thus peak inductor current under maximum VIN is calculated as 13.8A with Equation 12.