SLVSDU0B September 2017 – September 2019 BQ25910
PRODUCTION DATA.
Prior to converter switching, the flying and auxiliary capacitors, CFLY, and CAUX are charged to VBUS/2. After the capacitors have been pre-charged, the converter is enabled and the switching FETs QHSA – QLSB start switching. As a battery charger, the device deploys a highly-efficient 750-kHz three-level step-down switching regulator. The fixed frequency oscillator keeps tight control of the switching frequency under all conditions of input voltage, battery voltage, charge current and temperature, simplifying output filter design.
The charge current is soft-started into the desired value by starting from 300 mA and increasing the current up to ICHG programmed value over time. This "soft-start" also applies when increasing the ICHG register value while charging.