BQ25101YFPR

The BQ25101YFPR from Texas Instruments is a highly integrated single-cell Li-Ion/Li-Polymer linear charger in an ultra-small 1.6 x 0.9mm DSBGA package. It charges at up to 250mA with 1% voltage accuracy at 4.2V, while drawing only 75nA max from the battery when not charging. The device supports three charging phases (pre-charge, constant current, constant voltage) with programmable current levels and minimum 1mA termination. JEITA temperature compliance via an NTC thermistor ensures safe charging across temperature ranges. The 30V input rating with 6.5V OVP supports low-cost unregulated adapters.

The BQ25101 operates as a linear charger with three phases. When a valid input supply is detected (above UVLO and below OVP), the device performs ISET and OUT short checks. If the battery voltage is below the LOWV threshold, pre-charge begins at a programmable fraction of the fast-charge current. Once the battery exceeds LOWV, constant-current fast charging begins at the current programmed by the ISET resistor. When the battery reaches 4.2V, the constant-voltage phase holds the battery at the regulation voltage while current tapers. Charging terminates when the current drops below the termination threshold (half the pre-charge current). The JEITA-compliant NTC input adjusts charge parameters: cold conditions halve the fast-charge current, while hot conditions reduce the regulation voltage to 4.06V. Thermal regulation at 125°C reduces charge current to prevent overheating.

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• Bluetooth headset wearable charger with JEITA safety
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• IoT device coin-cell or small Li-Po battery management