1A, Single Input, Single Cell Li-Ion Battery Charger w/ 10k? NTC | Li-ion Linear Battery Charger IC 10-MSOP-PowerPAD 0 to 125# BQ24090DGQR Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BQ24090DGQR 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
- Portable Medical Devices : Enables safe charging for glucose meters, portable monitors, and diagnostic equipment
- Wearable Electronics : Compact solution for smartwatches, fitness trackers, and health monitors
- IoT Devices : Powers wireless sensors, smart home devices, and connected peripherals
- Portable Audio Equipment : Used in Bluetooth speakers, headphones, and audio recording devices
### Industry Applications
Consumer Electronics
- Dominant in mobile devices requiring fast charging capabilities
- Integrated in gaming peripherals and portable entertainment systems
Medical Technology
- Critical for FDA-compliant medical devices requiring reliable battery management
- Used in patient monitoring equipment and portable diagnostic tools
Industrial IoT
- Deployed in remote monitoring systems and industrial sensors
- Supports edge computing devices with limited power availability
### Practical Advantages and Limitations
Advantages:
- Integrated Power Path Management : Allows 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 : Includes battery temperature monitoring, overvoltage, and overcurrent protection
Limitations:
- Single-Cell Limitation : Only supports 4.2V/4.35V single-cell Li-ion/Li-polymer batteries
- Input Voltage Range : Limited to 3.9V to 6.2V input range
- Thermal Constraints : May require thermal management in high-ambient temperature environments
- External Component Count : Requires several external passive components for optimal operation
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Thermal Management
- Problem : Overheating during high-current charging
- Solution : Implement proper thermal vias, ensure adequate copper pour, and consider ambient temperature conditions
Pitfall 2: Input Voltage Instability
- Problem : Voltage spikes from USB or adapter sources
- Solution : Include input capacitors (10µF recommended) and transient voltage suppression if needed
Pitfall 3: Battery Connection Issues
- Problem : Poor battery contact causing charging interruptions
- Solution : Use robust battery connectors and implement proper strain relief
### Compatibility Issues with Other Components
Microcontroller Interfaces
- I²C Communication : Ensure pull-up resistors (typically 10kΩ) are properly sized
- GPIO Compatibility : Verify logic level matching with host processor
Power Management Integration
- DC-DC Converters : May require sequencing with other power rails
- Load Switches : Ensure proper timing between charger enable and load switching
Battery Protection
- External Protection Circuits : Coordinate with internal safety features to avoid conflicts
- Fuel Gauges : Ensure proper communication and timing synchronization
### PCB Layout Recommendations
Power Path Layout
```markdown
- Place input capacitors (C1, C2) within 2mm of VIN and GND pins
- Use thick traces (≥20 mil) for battery and input current paths
- Implement star grounding for analog and power grounds
```
Thermal Management
- Use thermal vias under the exposed pad (minimum 4×4 array)
- Connect thermal pad to large ground plane for heat dissipation
- Maintain adequate clearance for
