800-mA linear charger for 1-cell to 4-cell supercapacitor

The BQ25173 is an integrated 800-mA linear charger for 1- to 4-cell supercapacitors targeted at space-limited applications. The device has a single power output that charges the supercapacitor. The system load can be placed in parallel with the supercapacitor; the charge current is shared between the system and supercapacitor.

During charging, an internal control loop monitors the IC junction temperature and reduces the charge current if the internal temperature threshold, TREG, is exceeded. This feature allows for fast charging of a fully discharged supercapacitor.

The charger power stage and charge current sense functions are fully integrated. The charger function has high accuracy current and voltage regulation loops, charge status display, and charge function control. The charge voltage and fast-charge current are programmable through external resistors.