Part Number: BQ24728, BQ728, BQ24728RGRT
Function: Battery SMBus Charge Controller ( Power management , System Charge Power IC )
Package: QFN 20 Pin
Manfacturers: Texas Instruments
Image:
Description
The bq24728 is a high-efficiency, synchronous battery charger, offering low component count for space-constraint, multi-chemistry battery charging applications. The device uses two charge pumps to separately drive n-channel MOSFETs (ACFET, RBFET and BATFET) for automatic system power source selection. SMBus controlled input current, charge current, and charge voltage DACs allow for high regulation accuracies that can be programmed by the system power management micro-controller.
Features
- SMBus programmable charging parameters (voltage/current/input limit)
- High-efficiency synchronous charging architecture
- Automatic power source selection (adapter ↔ battery)
- Supports multi-chemistry battery systems (primarily Li-ion/Li-polymer)
- Low external component count
- High regulation accuracy via internal DACs
- Dual charge pump for full NMOS drive (no P-channel needed)
Pinout
Typical Circuit Usage
- Adapter input → ACFET/RBFET → system rail
- Synchronous buck stage → battery charging path
- BATFET controls battery connection/disconnection
- SMBus connected to EC (Embedded Controller)
Design Notes (Critical Points)
- Accurate current sensing resistor selection is essential for charge precision
- External MOSFET selection impacts efficiency and thermal performance
- SMBus firmware must properly configure charging profiles
- PCB layout must minimize switching loop inductance
- Thermal design critical for high-current charging scenarios
Applications
- Notebook / ultrabook / netbook platforms
- Handheld and portable terminals
- Industrial battery-powered equipment
- Medical portable systems
- Embedded battery charging modules
Advantages
- Highly flexible and programmable
- Efficient power-path control
- Reduced component count
- Suitable for smart battery systems
Alternative / Equivalent Products
- BQ24727 (closely related variant)
- BQ24725A
- ISL6255
- MAX8734
- LTC4012
BQ24728 Datasheet
BQ24725 Datasheet
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