USB-Friendly Li-Ion Battery Charger and Power-Path Management IC, Vout 5.5V 16-QFN -40 to 85# BQ24075RGTR Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BQ24075RGTR is a highly integrated single-chip Li-ion and Li-polymer battery charge management IC designed for space-limited portable applications. Its primary use cases include:
Portable Medical Devices
- Continuous Glucose Monitors : Provides reliable charging for diabetes management systems requiring 24/7 operation
- Portable Diagnostic Equipment : Supports rapid charging between patient visits while maintaining battery health
- Wearable Health Monitors : Enables compact design for fitness trackers and medical alert systems
Consumer Electronics
- Bluetooth Headsets : Manages charging cycles for devices with limited physical space
- Smart Watches : Supports trickle charging and termination for small battery capacities
- Portable Speakers : Handles varying input sources while protecting battery lifespan
Industrial Applications
- Handheld Scanners : Provides robust charging for devices used in warehouse and retail environments
- Data Loggers : Ensures reliable power management for remote monitoring equipment
- Portable Test Equipment : Supports precise charging control for sensitive measurement devices
### Industry Applications
- Medical Technology : Compliant with medical device safety standards, suitable for FDA-cleared devices
- Consumer Wearables : Optimized for compact form factors in smartwatch and fitness tracker markets
- IoT Devices : Ideal for connected sensors and edge computing devices requiring autonomous power management
- Industrial Automation : Suitable for handheld terminals and portable data collection systems
### Practical Advantages
Key Benefits:
- High Integration : Combines power path management, charging circuitry, and protection features in QFN-16 package
- Thermal Regulation : Automatic charge current reduction prevents overheating during high ambient temperature operation
- Input Current Optimization : Dynamically adjusts charge current based on available input power
- Small Footprint : 3mm × 3mm package enables ultra-compact designs
Limitations:
- Maximum Input Voltage : 6.5V absolute maximum limits compatibility with some higher-voltage adapters
- Charge Current : 1.5A maximum may be insufficient for high-capacity battery applications
- Temperature Monitoring : Requires external NTC thermistor for optimal battery temperature sensing
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Input Capacitor Selection
- Pitfall : Insufficient input capacitance causing voltage droop during load transients
- Solution : Use 10μF ceramic capacitor placed within 2mm of IN pin, with additional bulk capacitance if using high-impedance sources
Thermal Management
- Pitfall : Inadequate thermal relief leading to premature thermal shutdown
- Solution : Implement proper thermal vias under exposed pad, use 2oz copper when possible, and ensure adequate airflow
Battery Connection
- Pitfall : Long battery traces causing voltage sensing inaccuracies
- Solution : Route battery connections with wide traces, keep BAT capacitor close to IC, and use Kelvin connection for voltage sensing
### Compatibility Issues
Power Source Compatibility
- USB Sources : Fully compatible with USB 2.0/3.0 specifications, but may require current limiting for high-power USB-PD
- Wall Adapters : Works with 5V adapters; verify compatibility with unregulated or poorly regulated supplies
- Solar Panels : Requires additional input conditioning for variable voltage sources
Battery Chemistry
- Li-ion/Li-polymer : Optimized for standard 4.2V/cell chemistry
- Alternative Chemistries : Not suitable for LiFePO4 or other non-standard voltage requirements without external modification
### PCB Layout Recommendations
Power Path Routing
- Input Section : Use star-point grounding for input and output capacitors
- Battery Traces : Minimum 20mil width for
