Product details


Number of series cells 2, 3, 4 Charge current (Max) (A) 8 Operating Vin (Max) (V) 24 Cell chemistry Li-Ion/Li-Polymer Battery charge voltage (Min) (V) 8 Battery charge voltage (Max) (V) 18 Absolute Vin (safety rating) (Max) ((V)) 30 Control topology Switch-Mode Buck Control interface SMBus Features BAT temp thermistor monitoring (hot/cold profile) Operating Vin (Min) (V) 5 Rating Catalog open-in-new Find other Battery charger ICs

Package | Pins | Size

VQFN (RGE) 24 16 mm² 4 x 4 open-in-new Find other Battery charger ICs


  • NMOS-NMOS Synchronous Buck Converter with 600 kHz Frequency and >95% Efficiency
  • 30-ns Minimum Driver Dead-time and 99.5% Maximum Effective Duty Cycle
  • High-Accuracy Voltage and Current Regulation
    • ±0.5% Charge Voltage Accuracy
    • ±3% Charge Current Accuracy
    • ±3% Adapter Current Accuracy
    • ±2% Input Current Sense Amp Accuracy
  • Integration
    • Internal Loop Compensation
    • Internal Soft-Start
  • Safety
    • Input Overvoltage Protection (OVP)
    • Dynamic Power Management (DPM) with Status Indicator
  • Supports Two, Three, or Four Li+ Cells
  • 5 - 24 V AC/DC-Adapter Operating Range
  • Analog Inputs with Ratiometric Programming via Resistors or DAC/GPIO Host Control
    • Charge Voltage (4-4.512 V/cell)
    • Charge Current (up to 8 A, with 10-m Sense Resistor)
    • Adapter Current Limit (DPM)
  • Status and Monitoring Outputs
    • AC/DC Adapter Present with Programmable Voltage Threshold
    • DPM Loop Active (DPMDET)
    • Current Drawn from Input Source
  • Supports Any Battery Chemistry: Li+, NiCd, NiMH, Lead Acid, etc.
  • Charge Enable
  • 10-µA Off-State Battery Current
  • 24-pin, 4x4-mm QFN Package
    • Notebook and Ultra-Mobile Computers
    • Portable Data-Capture Terminals
    • Portable Printers
    • Medical Diagnostics Equipment
    • Battery Bay Chargers
    • Battery Back-Up Systems

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The bq24705 is a high-efficiency, synchronous battery charger with integrated compensation, offering low component count for space-limited multi-chemistry battery charging applications. Charge current and voltage programming allows high regulation accuracies, and can be either hardwired with resistors, or programmed by the system power-management microcontroller using a DAC or GPIOs.

The bq24705 charges two, three, or four series Li+ cells, supporting up to 8 A of charge current, and is available in a 24-pin, 4x4-mm thin QFN package.

The bq24705 features Dynamic Power Management (DPM) and input power limiting. These features reduce battery charge current when the input power limit is reached to avoid overloading the AC adapter when supplying the load and the battery charger simultaneously. A highly-accurate current-sense amplifier enables precise measurement of input current from the AC adapter to monitor the overall system power.

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Technical documentation

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Type Title Date
* Data sheet Host-Controlled Multi-Chemistry Battery Charger With Low Input Power Detect datasheet (Rev. B) Mar. 26, 2009
Technical article When to use rechargeable batteries in small battery applications Oct. 01, 2019
Technical article Should I use a linear charger or a switching charger? Oct. 31, 2015
Technical article Summertime and the livin' is easy Jun. 20, 2014

Design & development

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