USB-Friendly Li-Ion Battery Charger and Power-Path Management IC, Vout 200mV above Vbat | Linear 16-QFN -40 to 85# BQ24072RGTR Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BQ24072RGTR is a highly integrated single-cell Li-ion and Li-polymer battery charger IC with power path management, designed for space-constrained portable applications. Key use cases include:
Primary Applications:
- Smartphones and Tablets : Provides simultaneous charging and system operation capability
- Wearable Devices : Compact solution for smartwatches and fitness trackers
- Portable Medical Devices : Reliable charging for glucose monitors, portable diagnostics
- Bluetooth Headsets : Efficient power management for audio accessories
- IoT Devices : Power management for sensors and edge computing devices
Industry Applications:
- Consumer Electronics : Mobile phones, digital cameras, portable gaming devices
- Medical Technology : Hearing aids, portable monitoring equipment
- Industrial Equipment : Handheld scanners, portable test instruments
- Automotive Accessories : Aftermarket car kits, portable navigation systems
### Practical Advantages
Key Benefits:
- Integrated Power Path Management : Enables simultaneous charging and system operation
- High Efficiency : Up to 92% charging efficiency with 1.5A capability
- Compact Footprint : 3mm × 3mm QFN package saves board space
- Thermal Regulation : Automatic charge current reduction during high temperature conditions
- Safety Features : Multiple protection circuits including thermal shutdown and battery detection
Limitations:
- Single-Cell Only : Limited to 4.2V Li-ion/Li-polymer batteries
- Input Voltage Range : 4.35V to 6.4V input range may not suit all applications
- Thermal Constraints : Maximum 1.5A charging current requires proper thermal management
- Cost Consideration : Higher component cost compared to basic charger ICs
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Thermal Management Issues:
- Problem : Overheating during maximum current charging
- Solution : Implement adequate PCB copper pours for heat dissipation
- Recommendation : Use thermal vias under the package and ensure proper airflow
Input Voltage Stability:
- Problem : Input voltage drops causing charger reset
- Solution : Place input capacitor (10μF) close to VIN pin
- Recommendation : Use low-ESR ceramic capacitors for stable operation
Battery Connection Problems:
- Problem : Intermittent charging due to poor battery connection
- Solution : Implement robust battery connector design
- Recommendation : Include battery detection circuitry for safety
### Compatibility Issues
Microcontroller Interface:
- The STAT and PG outputs require pull-up resistors (10kΩ typical) when interfacing with MCUs
- I²C communication needs proper level shifting if MCU operates at different voltage levels
Power Supply Compatibility:
- Ensure input power supply can deliver required current without voltage sag
- USB OTG functionality requires specific host controller compatibility
Battery Protection:
- External protection circuits may be needed for additional safety margins
- Compatible with standard Li-ion protection ICs
### PCB Layout Recommendations
Power Path Layout:
- Place input and output capacitors as close as possible to respective pins
- Use wide traces for high-current paths (VIN, BAT, SYS)
- Maintain minimum 20-mil trace width for 1.5A current paths
Thermal Management:
- Use the exposed thermal pad for effective heat dissipation
- Implement multiple thermal vias connecting to ground plane
- Ensure adequate copper area around the device
Signal Integrity:
- Route sensitive signals (TS, STAT, PG) away from switching nodes
- Keep I²C lines (SDA, SCL) together with proper spacing
- Use ground plane for noise reduction
