Single-cell Li-Ion linear charger with USB interface
The BQ24025DRCRG4 is a linear charger for single-cell Lithium-Ion or Lithium-Polymer batteries, part of TI's bqTINY™-II series. It accepts power from a USB port or a regulated 5V supply, with a maximum input voltage of 6.5V. The charge current is programmable up to 500 mA, and the battery termination voltage is fixed at 4.2V. The device integrates over-temperature fault protection and programmable charge-current and charge-timer features.
Charge current and termination voltage
Maximum charge current is 500 mA, set by an external resistor. This ceiling suits small-form-factor batteries in wearables, IoT sensors, or handheld instruments where charge time is secondary to thermal management. The 4.2V battery pack voltage is the standard termination for single-cell Li-Ion and Li-Polymer cells. The constant-current / constant-voltage (CC/CV) profile is typical for linear chargers: the current is regulated until the battery reaches 4.2V, then the voltage is held while the current tapers. The programmable timer provides a safety timeout if the battery does not reach full charge within the set window.
Surface-mount assembly is standard.