ZHCSN85 January 2021 LM5156 , LM51561
PRODUCTION DATA
When selecting the inductor, consider three key parameters: inductor current ripple ratio (RR), falling slope of the inductor current, and RHP zero frequency (fRHP).
Inductor current ripple ratio is selected to have a balance between core loss and copper loss. The falling slope of the inductor current must be low enough to prevent subharmonic oscillation at high duty cycle (additional RSL resistor is required if not). Higher fRHP (= lower inductance) allows a higher crossover frequency and is always preferred when using a small value output capacitor.
The inductance value can be selected to set the inductor current ripple between 30% and 70% of the average inductor current as a good compromise between RR, FRHP, and inductor falling slope.