Product details


Number of series cells 1 Charge current (Max) (A) 0.8 Operating Vin (Max) (V) 6.45 Cell chemistry Li-Ion/Li-Polymer Battery charge voltage (Min) (V) 4.2 Battery charge voltage (Max) (V) 4.2 Absolute Vin (safety rating) (Max) ((V)) 30 Control topology Linear Control interface Standalone (RC-Settable) Features BAT temp thermistor monitoring (hot/cold profile), Input OVP Operating Vin (Min) (V) 3.5 Rating Catalog open-in-new Find other Battery charger ICs

Package | Pins | Size

SOT-23 (DBV) 6 5 mm² 2.9 x 1.6 open-in-new Find other Battery charger ICs


  • Charging
    • 1% Charge Voltage Accuracy
    • 10% Charge Current Accuracy
    • Low Battery Leakage Current (1 µA)
    • Programmable Charge Current using External Resistor up to 800 mA
    • 4.2-V Li-Ion and Li-Pol Charger
  • Protection
    • 30-V Input Rating; with 6.6-V Input Overvoltage Protection
    • Input Voltage Dynamic Power Management
    • 125°C Thermal Regulation; 150°C Thermal Shutdown Protection
    • OUT Short-Circuit Protection and ISET Short Detection
    • Overtemperature Sensing Protection Through NTC
    • Fixed 10-Hour Safety Timer
  • System
    • Status Indication – Charging/Done
    • Available in Small SOT-23 Package

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The bq21040 device is a highly integrated Li-Ion and Li-Pol linear battery charger device targeted at space-limited portable applications. The device operates from either a USB port or AC adapter. The high input voltage range with input overvoltage protection supports low-cost unregulated adapters.

The bq21040 has a single power output that charges the battery. A system load can be placed in parallel with the battery as long as the average system load does not keep the battery from charging fully during the 10 hour safety timer.

The battery is charged in three phases: conditioning, constant current and constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if an internal temperature threshold is exceeded.

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 termination. The pre-charge current and termination current threshold are fixed to 20% and 10%, respectively. The fast charge current value is programmable through an external resistor.

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Technical documentation

= Top documentation for this product selected by TI
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Type Title Date
* Datasheet bq21040 0.8-A, Single-Input, Single Cell Li-Ion and Li-Pol Battery Charger datasheet (Rev. D) Jan. 08, 2019
Technical articles When to use rechargeable batteries in small battery applications Oct. 01, 2019
Application note BQ2404x, BQ2405x, and BQ2409x Frequently Asked Questions Feb. 25, 2019
Application note 2Q 2016 Analog Applications Journal Issue Apr. 26, 2016
Application note Battery-charging considerations for low-power applications Apr. 26, 2016
User guide bq21040 0.8-A Single-Input, Single-Cell Li-Ion Battery Charger EVM User's Guide Mar. 21, 2016
Technical articles Should I use a linear charger or a switching charger? Oct. 30, 2015
Technical articles Summertime and the livin' is easy Jun. 20, 2014

Design & development

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Hardware development

document-generic User guide
The bq2404x series of devices are highly integrated Li-ion linear charger devices targeted at space-limited portable applications. The devices operate from either a USB port or AC adapter and has a single power output that charges the battery. A system load can be placed in parallel with the battery (...)
  • 5-V input operates from either USB port or AC adapter
  • Single power output with 1% battery voltage regualtion accuracy
  • 4.2V Li-Ion and Li-Pol Charger
  • 6.6V overvoltage protection; 125 C thermal regualtion; 10 hour fixed safety timer
  • Available in small SOT-23 package

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Package Pins Download
SOT-23 (DBV) 6 View options

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