Battery Charger with System Power Selector BQ24751

DESCRIPTION
The bq24751 is a high-efficiency, synchronous battery charger with integrated compensation and
system power selector logic, offering low component count for space-constrained multi-chemistry battery
charging applications. Ratiometric charge current and voltage programming allows very high regulation
accuracies, and can be either hardwired with resistors or programmed by the system power-management microcontroller using a DAC or GPIOs.
The bq24751 charges two, three, or four series Li+ Li+
– Programmable Inrush Adapter Powe available in a 28-pin, 5x5-mm thin QFN package.
NMOS-NMOS Synchronous Buck Converter · 28-pin, 5x5-mm QFN package with 300 kHz Frequency and >95% Efficiency
· 30-ns Minimum Driver Dead-time and 99.5% Maximum Effective Duty Cycle · Notebook and Ultra-Mobile Computers

FEATURES
– 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-mW sense resistor)
– Adapter Current Limit (DPM)
· Status and Monitoring Outputs
– AC/DC Adapter Present with Programmable Voltage Threshold
– Current Drawn from Input Source
· Battery Learn Cycle Control
· Supports Any Battery Chemistry: Li+, NiCd, NiMH, Lead Acid, etc.
· Charge Enable

APPLICATIONS
· High-Accuracy Voltage and Current · Portable Data Capture Terminals Regulation · Portable Printers
– ± 0.5% Charge Voltage Accuracy · Medical Diagnostics Equipment – ± 3% Charge Current Accuracy · Battery Bay Chargers – ± 3% Adapter Current Accuracy · Battery Back-up Systems
– ± 2% Input Current Sense Amp Accuracy
· Integration
– Automatic System Power Selection From

CONTINUED)

The bq24751 controls external switches to prevent battery discharge back to the input, connect the adapter to the system, and to connect the battery to the system using 6-V gate drives for better system efficiency. For maximum system safety, inrush-power limiting provides instantaneous response to high input voltage multiplied by current. This AC Over-Power protection (ACOP) feature limits the input-switch power to the programmed level on the ACOP pin, and latches off if the high-power condition persists to prevent overheating. The bq24751 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.


Switching Regulator for Notebook BD95242MUV

 

BQ24751