JAJSFD5D March 2015 – October 2022 BQ25890 , BQ25892
PRODUCTION DATA
The device has 1.5 MHz switching frequency to allow the use of small inductor and capacitor values. The Inductor saturation current should be higher than the charging current (ICHG) plus half the ripple current (IRIPPLE):
The inductor ripple current depends on input voltage (VBUS), duty cycle (D = VBAT/VVBUS), 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 (20–40%) maximum charging current as a trade-off between inductor size and efficiency for a practical design.