BQ24745 Status: ACTIVE

Product Information

Features

• 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
  • Input Overvoltage Protection (OVP)
  • Dynamic Power Management (DPM)
• Up to 19.2 V Battery Voltage
• 6 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-µBattery Current with Adapter Removed
• < 1 mA Input DCIN Current with Adapter Present and Charge Disabled
• 28-pin, 5x5-mm² QFN Package
• APPLICATIONS
  • Notebook and Ultra-Mobile Computers
  • Portable Data-Capture Terminals
  • Portable Printers
  • Medical Diagnostics Equipment
  • Battery Bay Chargers
  • Battery Back-up Systems

Description

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 one, two, three, or four series Li+ cells, and is available in a 28-pin, 5x5 mm² 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.