SLUSA75B July 2010 – January 2020 BQ24650
The BQ24650 has a 600-kHz switching frequency to allow the use of small inductor and capacitor values. Inductor saturation current must be higher than the charging current (ICHG) plus half the ripple current (IRIPPLE):
Inductor ripple current depends on input voltage (VIN), duty cycle (D = VOUT/VIN), switching frequency (fs), and inductance (L):
The maximum inductor ripple current happens with D = 0.5 or close to 0.5. Usually inductor ripple is designed in the range of 20% to 40% of the maximum charging current as a trade-off between inductor size and efficiency for a practical design.