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. SMBus 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. The bq24745 charges two, three, or four
●series Li+ cells, and is available in a 28-pin, 5x5 mm2
●thin QFN package.
●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
●– Charge Voltage DAC (1.024 V–19.2 V)
●– Charge Current DAC (128 mA–8.064 A)
●– Adapter Current Limit DPM DAC (256mA–11.004 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.
●• Cells Pin Supports Two to Four Li-Ion Cells
●• Charge Enable Pin
●• < 10-µBattery Current with Adapter Removed
●APPLICATIONS
●• < 1 mA Input DCIN Current with Adapter Present and Charge Disabled
●• 28-pin, 5x5-mm2 QFN Package
●• Notebook and Ultra-Mobile Computers
●• Portable Data-Capture Terminals
●• Portable Printers
●• Medical Diagnostics Equipment
●• Battery Bay Chargers
●• Battery Back-up Systems
