SLUSDL9A June 2019 – January 2021 BQ25125
When the battery above VBATUVLO is connected with no input source, the battery discharge FET is turned on. After the battery rises above VBATUVLO and the deglitch time is reached, the SYS output starts to rise. The current from PMID and SYS is not regulated, but is protected by a short circuit current limit. If the short circuit limit is reached for the deglitch time (tDGL_SC), the battery discharge FET is turned off for the recovery time (tREC_SC). After the recovery time, the battery FET is turned on to test if the short has been removed. If it has not, the FET turns off and the process repeats until the short is removed. This process protects the internal FET from over current. During this event PMID will likely droop and cause SYS to go out of regulation.
To provide designers the most flexibility in optimizing their system, an adjustable BATUVLO is provided. When the voltage drops below the VBATUVLO threshold, the battery discharge FET is turned off. Deeper discharge of the battery enables longer times between charging, but may shorten the battery life. The BATUVLO is adjustable with a fixed 150-mV hysteresis.
If a valid VIN is connected during active battery mode, VIN > VUVLO, the supplement and battery discharge FET is turned on when the battery voltage is above the minimum VBATUVLO.
Drive CD high or write the CE register to disable charge when VIN > VUVLO is present. CD is internally pulled down. When exiting this mode, charging resumes if VIN is present, CD is low and charging is enabled.
All HOST interfaces ( CD, SDA/SCL, INT, RESET and LSCTRL) are active no later than 5 ms after SYS reaches the programmed level.