SLUSDC7A March 2020 – November 2020 BQ25306
The 1.2-MHz switching frequency allows the use of small inductor and capacitor values. Inductance value is selected based on maximum input voltage VVBUS_MAX in applications. 1-µH inductor is recommended if VVBUS_MAX < 6.2V and 2.2-µH inductor is recommended if VVBUS_MAX > 6.2V for either 1-cell or 2-cell battery charge. An inductor saturation current ISATshould be higher than the charging curren ICHG plus half the ripple current IRIPPLE:
The inductor ripple current IRIPPLE depends on the input voltage (VVBUS), the duty cycle (D = VBAT/VVBUS), the switching frequency (fS) and the inductance (L).
The maximum inductor ripple current occurs when the duty cycle (D) is 0.5 or approximately 0.5.