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SMBus up to 4 cell level 2 Buck battery chager to support Multiple battery chemistries

BQ24745 is not recommended for new designs
Although this product continues to be in production to support previous designs, we don't recommend it for new designs. Consider one of these alternates:
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Similar functionality to the compared device
BQ24725A ACTIVE SMBus 1-4 cell Buck battery charge controller with N-Channel power MOSFET selector This product is 1-4S Li+ Battery SBMus charger controller

Product details

Number of series cells 2, 3, 4 Charge current (max) (A) 10 Vin (max) (V) 24 Cell chemistry Li-Ion/Li-Polymer Battery charge voltage (min) (V) 0 Battery charge voltage (max) (V) 24 Absolute max Vin (max) (V) 30 Control topology Switch-Mode Buck Control interface SMBus Features Power Path Vin (min) (V) 7 Rating Catalog Operating temperature range (°C) 0 to 0
Number of series cells 2, 3, 4 Charge current (max) (A) 10 Vin (max) (V) 24 Cell chemistry Li-Ion/Li-Polymer Battery charge voltage (min) (V) 0 Battery charge voltage (max) (V) 24 Absolute max Vin (max) (V) 30 Control topology Switch-Mode Buck Control interface SMBus Features Power Path Vin (min) (V) 7 Rating Catalog Operating temperature range (°C) 0 to 0
VQFN (RHD) 28 25 mm² 5 x 5
  • NMOS-NMOS Synchronous Buck Converter with
    300-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
    • Input Current Comparator, With Adjustable
      Threshold and Hysteresis
    • Internal Soft-Start
  • Safety
    • Dynamic Power Management (DPM)
  • Up to 19.2-V Battery Voltage
  • 7-V–24-V AC/DC-Adapter Operating Range
  • Simplified SMBus Control Interface
    • Charge Voltage DAC (1.024 V–19.2 V)
    • Charge Current DAC (128 mA–8.064 A)
    • Adapter Current Limit DPM DAC
      (256 mA–11.008 A)
  • Status and Monitoring Outputs
    • AC/DC Adapter Present With
      Adjustable Voltage Threshold
    • Input Current Comparator With Adjustable
      Threshold and Hysteresis
    • Current Sense Amplifier for Current Drawn
      From Input Source
  • Charge Any Battery Chemistry: Li+, NiCd,
    NiMH, Lead Acid, Etc.
  • Charge Enable Pin
  • < 10-µA Battery Current With Adapter Removed
  • < 1-mA Input DCIN Current With Adapter
    Present and Charge Disabled
  • 28-Pin, 5-mm × 5-mm QFN Package
  • NMOS-NMOS Synchronous Buck Converter with
    300-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
    • Input Current Comparator, With Adjustable
      Threshold and Hysteresis
    • Internal Soft-Start
  • Safety
    • Dynamic Power Management (DPM)
  • Up to 19.2-V Battery Voltage
  • 7-V–24-V AC/DC-Adapter Operating Range
  • Simplified SMBus Control Interface
    • Charge Voltage DAC (1.024 V–19.2 V)
    • Charge Current DAC (128 mA–8.064 A)
    • Adapter Current Limit DPM DAC
      (256 mA–11.008 A)
  • Status and Monitoring Outputs
    • AC/DC Adapter Present With
      Adjustable Voltage Threshold
    • Input Current Comparator With Adjustable
      Threshold and Hysteresis
    • Current Sense Amplifier for Current Drawn
      From Input Source
  • Charge Any Battery Chemistry: Li+, NiCd,
    NiMH, Lead Acid, Etc.
  • Charge Enable Pin
  • < 10-µA Battery Current With Adapter Removed
  • < 1-mA Input DCIN Current With Adapter
    Present and Charge Disabled
  • 28-Pin, 5-mm × 5-mm QFN Package

The bq24745 is a high-efficiency, synchronous battery charger with an integrated input-current comparator, offering low component count for space-constrained, multi-chemistry battery-charging applications. The input-current, charge-current, and charge-voltage DACs allow very high regulation accuracies that can be easily programmed by the system power-management microcontroller using the SMBus interface. The bq24745 charges two, three, or four series Li+ cells, and is available in a 28-pin, 5-mm × 5 mm QFN package.

The bq24745 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 adaptor 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, allowing monitoring the overall system power. If the adapter current is above the programmed low-power threshold, a signal is sent to host so that the system optimizes its performance to the power available from the adapter. An integrated comparator monitors the input current through the current-sense amplifier, and indicates when the input current exceeds a programmable threshold limit.

The bq24745 is a high-efficiency, synchronous battery charger with an integrated input-current comparator, offering low component count for space-constrained, multi-chemistry battery-charging applications. The input-current, charge-current, and charge-voltage DACs allow very high regulation accuracies that can be easily programmed by the system power-management microcontroller using the SMBus interface. The bq24745 charges two, three, or four series Li+ cells, and is available in a 28-pin, 5-mm × 5 mm QFN package.

The bq24745 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 adaptor 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, allowing monitoring the overall system power. If the adapter current is above the programmed low-power threshold, a signal is sent to host so that the system optimizes its performance to the power available from the adapter. An integrated comparator monitors the input current through the current-sense amplifier, and indicates when the input current exceeds a programmable threshold limit.

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Technical documentation

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Type Title Date
* Data sheet SMBus-Controlled Multi-chemistry Battery Charger With Input Current datasheet (Rev. D) 05 Oct 2011
Application note How to Review a Multicell Switching Charger Schematic 21 Sep 2011
More literature Журнал по применению аналоговых компонентов 1 кв. 2010 23 Sep 2010
Analog Design Journal Li-ion battery-charger solutions for JEITA compliance 29 Jan 2010

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Driver or library

SLUC098 bq24745 Driver (USB EV2300) Installer

Supported products & hardware

Supported products & hardware

Products
Battery charger ICs
BQ24745 SMBus up to 4 cell level 2 Buck battery chager to support Multiple battery chemistries
Support software

SLUC097 bq24745EVSWv101

Supported products & hardware

Supported products & hardware

Products
Battery charger ICs
BQ24745 SMBus up to 4 cell level 2 Buck battery chager to support Multiple battery chemistries
Reference designs

PMP9668 — Universal uP Controlled Battery Charger 24Vin 10 Aout max, 5/12V 2A & 5V 4A, 2 USB Ports Ref Design

BQ24745 is a host controlled synchronous buck battery charger capable of charging batteries at up to 19.2V and up to 8 A normally, extended to 10 A with use of 8 mOhm battery sense resistor. The power train is capable of 8 A with convection only cooling and 10 A with moderate fan cooling (~200 (...)
Test report: PDF
Schematic: PDF
Package Pins Download
VQFN (RHD) 28 View options

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