Li-Ion Charger with Dynamic Power-Path Management, Output regulated to 6V 20-VQFN -40 to 85# BQ24071RHLR Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BQ24071RHLR is a highly integrated single-cell Li-ion and Li-polymer battery charger IC with integrated power path management, designed for space-constrained portable applications. Key use cases include:
Primary Applications:
- Smartphones and Tablets : Provides simultaneous battery charging and system operation from USB or adapter inputs
- Wearable Devices : Compact 20-WQFN package (3.5mm × 3.5mm) ideal for smartwatches and fitness trackers
- Portable Medical Devices : Ensures reliable charging for glucose meters, portable monitors, and diagnostic equipment
- IoT Devices : Supports battery-powered sensors and edge computing devices with limited space
Specific Implementation Examples:
- USB-Powered Systems : Automatically detects USB input current limits (100mA/500mA/1.5A)
- Wall Adapter Charging : Supports up to 1.5A charge current with high-input voltage range (4.35V to 6.5V)
- Battery-Powered Systems : Maintains system operation even with deeply discharged batteries
### Industry Applications
Consumer Electronics
- Dominant in smartphones, tablets, and portable gaming devices
- Used in Bluetooth headphones and portable speakers
- Implementation in digital cameras and camcorders
Medical Technology
- Portable patient monitoring systems
- Handheld diagnostic equipment
- Medical wearables requiring reliable power management
Industrial IoT
- Asset tracking devices
- Environmental monitoring sensors
- Industrial handheld terminals
Automotive Accessories
- Aftermarket car entertainment systems
- Portable navigation devices
- Dash cameras and telematics systems
### Practical Advantages and Limitations
Advantages:
- Integrated Power Path Management : Allows system to operate immediately when connected to power source, even with dead battery
- Small Form Factor : 20-pin WQFN package saves board space
- High Integration : Reduces external component count (requires only 5 external components)
- Thermal Regulation : Automatically reduces charge current to control die temperature
- Safety Features : Includes battery temperature monitoring, charge safety timer, and overvoltage protection
Limitations:
- Single-Cell Only : Limited to 4.2V/4.35V battery chemistries
- Maximum 1.5A Charge Current : Not suitable for high-capacity battery applications requiring fast charging
- No Wireless Charging Integration : Requires external circuitry for wireless power applications
- Temperature Monitoring : Requires external NTC thermistor for optimal battery temperature sensing
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Input Source Selection Issues
- Pitfall : Incorrect input current limit setting causing system instability
- Solution : Properly configure ILIM pin resistor for desired input current limit (100mA to 1.5A)
Thermal Management Problems
- Pitfall : Inadequate thermal design leading to reduced charge current during operation
- Solution : Ensure sufficient copper area for thermal dissipation and follow layout guidelines
Battery Connection Concerns
- Pitfall : Poor battery connection detection causing charging failures
- Solution : Implement proper battery detection circuitry and ensure reliable mechanical connections
### Compatibility Issues with Other Components
Microcontroller Interfaces
- Compatibility : Works with most microcontrollers through STAT and PG outputs
- Consideration : Ensure GPIO voltage levels match IC logic levels (1.8V/3.3V compatible)
Power Management ICs
- Conflict Potential : May interfere with other power management ICs if not properly sequenced
- Resolution : Implement proper power sequencing and enable/disable controls
USB Controllers
- Integration : Compatible with standard USB controllers but requires proper current
