The bq24740 is a high-efficiency, synchronous battery charger with integrated compensation, offering low component count for space-constrained multi-chemistry battery charging applications. Ratiometric 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 bq24740 charges two, three, or four series Li+ cells, supporting up to 10 A of charge current, and is available in a 28-pin, 5x5-mm thin QFN package.

The bq24740 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 current-sense amplifier enables precise measurement of input current from the ac adapter to monitor 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 power performance according to what is available from the adapter.

• 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
  • 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 10 A, with 10-m Sense Resistor)
  • Adapter Current Limit (DPM)
• Status and Monitoring Outputs
  • AC/DC Adapter Present with Programmable Voltage Threshold
  • Low Input-Power Detect with Adjustable Threshold and Hysteresis
  • DPM Loop Active
  • Current Drawn from Input Source
• Battery Discharge Current Sense with No Adapter, or Selectable Low-Iq mode
• Supports Any Battery Chemistry: Li+, NiCd, NiMH, Lead Acid, etc.
• Charge Enable
• 10-µA Off-State Current
• 28-pin, 5x5-mm QFN package
• APPLICATIONS
  • Notebook and Ultra-Mobile Computers
  • Portable Data-Capture Terminals
  • Portable Printers
  • Medical Diagnostics Equipment
  • Battery Bay Chargers
  • Battery Back-up Systems