ZHCSJI9A March 2019 – June 2019 BQ25886
PRODUCTION DATA.
After the input current limit is set, the PG pin is pulled LOW, and the converter is enabled, allowing the QHS and QLS to start switching.Before charging begins, the battery discharge source (IBAT_DISCHG) is enabled automatically to detect the presence of battery. BATFET stays on to charge the battery. The device provides soft-start when system rail is ramped up.
As a battery charger, the device deploys a highly efficient 1.5-MHz boost 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.
In order to improve light-load efficiency, the device switches to PFM (Pulse Frequency Modulation) control at light load when battery is below minimum system voltage setting or charging is disabled. During the PFM operation, the switching duty cycle is set by the ratio of SYS and VBUS.