BQ24045DSQR

The BQ24045DSQR from Texas Instruments is a highly integrated linear battery charger designed for single-cell Li-Ion and Li-Polymer batteries with 4.35V high-voltage chemistry support. It integrates a complete charging solution in a tiny 2 x 2 mm WSON-10 package, including power FETs, current sensing, and charge status indication. The device supports USB 100mA/500mA input current limiting and features programmable fast-charge and termination currents via external resistors. JEITA-compatible NTC monitoring adjusts charging behavior based on battery temperature, while IEC 62368-1 certification provides safety assurance for consumer applications.

The BQ24045DSQR charges the battery in three phases: precharge (conditioning), constant current (fast charge), and constant voltage. In the precharge phase, a reduced current is applied to deeply discharged batteries. When the battery voltage rises above the precharge threshold, the device transitions to the constant-current phase where the fast-charge current is regulated via the ISET resistor. Once the battery reaches 4.35V, the constant-voltage phase begins and the charge current gradually decreases. When the current drops below the programmable termination threshold, charging stops and the CHG pin indicates completion. The TS pin monitors battery temperature through an NTC thermistor, implementing JEITA guidelines that reduce charge current at cold temperatures and limit voltage at hot temperatures. The integrated VIN-DPM feature reduces charge current if the input voltage drops, preventing USB port voltage collapse.

• TWS earbuds and headsets requiring compact charger with 4.35V chemistry
• Smartwatches and fitness bands with USB charging
• Wireless speakers and portable audio devices
• Mobile POS terminals and handheld scanners
• Portable medical devices with safety certification requirements