bqSWITCHER(TM) Synchronous, Switch-Mode Li-Ion Charger w/ 2-A FET in QFN, 1-Cell, Standalone Version# BQ24100RHLR Technical Documentation
*Manufacturer: Texas Instruments (BB/TI)*
## 1. Application Scenarios
### Typical Use Cases
The BQ24100RHLR is a highly integrated lithium-ion/polymer battery charge management IC designed for space-constrained portable applications. Typical implementations include:
Primary Charging Applications:
- Single-cell Li-ion/Li-polymer battery charging from USB or AC adapter sources
- Smartphones and feature phones requiring 1A charging capability
- Portable media players and handheld gaming devices
- Bluetooth headsets and wireless accessories
- Digital cameras and portable recording devices
Power Management Integration:
- Systems requiring power path management for simultaneous operation and charging
- Applications needing thermal regulation for optimal charging safety
- Devices with low-battery recovery and trickle charge requirements
### Industry Applications
Consumer Electronics:
- Mobile communication devices requiring compact charging solutions
- Wearable technology with limited PCB real estate
- Portable medical monitoring equipment
- Handheld test and measurement instruments
Industrial Applications:
- Portable data collection terminals
- Inventory management scanners
- Remote monitoring devices with battery backup
- Field service equipment requiring reliable charging
### Practical Advantages and Limitations
Advantages:
- High Integration : Combines power MOSFETs, current sensor, and reverse blocking protection in a single 3×3 mm QFN package
- Flexible Input Sources : Automatic detection between USB (500mA) and wall adapter (1A) modes
- Thermal Regulation : Maintains optimal charging current based on die temperature
- Safety Features : Includes battery temperature monitoring, charge timer, and reverse current protection
- Compact Solution : Minimal external components required (typically 5-7 passive components)
Limitations:
- Fixed Charge Current : Maximum 1A charging current may be insufficient for high-capacity batteries
- Input Voltage Range : Limited to 4.35V to 6.5V input range
- Package Thermal Constraints : 3×3 mm QFN may require thermal vias for high-power dissipation scenarios
- No I²C Interface : Lacks programmability compared to newer charge management ICs
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Input Source Selection Issues:
- Pitfall : Incorrect detection between USB and wall adapter modes
- Solution : Ensure proper STAT pin configuration and adequate input capacitance (≥10μF)
Thermal Management Challenges:
- Pitfall : Excessive temperature rise during high-current charging
- Solution : Implement proper thermal vias, adequate copper pour, and consider derating charge current in high-ambient environments
Battery Connection Problems:
- Pitfall : Reverse battery connection damaging the IC
- Solution : Include reverse polarity protection or ensure proper battery connector keying
### Compatibility Issues with Other Components
Microcontroller Interfaces:
- The STAT and PG outputs are open-drain, requiring pull-up resistors when interfacing with microcontrollers
- Ensure logic level compatibility (typically 3.3V systems)
Power Supply Sequencing:
- The IC requires proper power-up sequencing to avoid latch-up conditions
- Input voltage should be applied before or simultaneously with VCC
Battery Protection Circuits:
- Compatible with standard battery protection modules but may require additional consideration for impedance matching
- Ensure protection circuit doesn't interfere with charge termination algorithms
### PCB Layout Recommendations
Power Path Routing:
- Use wide traces for BAT, SYS, and input power paths (minimum 20 mil width for 1A current)
- Keep input capacitor (C1) as close as possible to IN and GND pins
- Place output capacitor (C2) near BAT pin with short return paths
Thermal Management:
- Utilize the exposed thermal pad with
