bqTINY(TM) Linear, 1-cell (4.2V) Li-Ion Charger w/ 1-A FET, Charge & Term Enable in QFN/MLP-10# BQ24013DRCRG4 Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BQ24013DRCRG4 is a highly integrated single-cell Li-ion battery charger IC designed for space-constrained portable applications. Typical use cases include:
- Portable Medical Devices : Glucose meters, portable monitors, and wearable health trackers requiring reliable battery charging with thermal protection
- Consumer Electronics : Bluetooth headsets, smartwatches, fitness trackers, and portable audio devices
- IoT Devices : Wireless sensors, smart home devices, and portable data loggers needing autonomous charging control
- Industrial Handhelds : Barcode scanners, portable test equipment, and data collection terminals
### Industry Applications
Medical Industry : Used in FDA Class II medical devices where precise charging termination and safety are critical. The integrated thermal regulation ensures safe operation in various environmental conditions.
Consumer Electronics : Ideal for products requiring USB-compatible charging with automatic power source detection. The device supports both USB and adapter power inputs with different current limits.
Automotive Accessories : Aftermarket automotive devices like dash cams and GPS trackers benefit from the wide input voltage range (4.35V to 6.5V) and robust protection features.
### Practical Advantages and Limitations
Advantages:
- High Integration : Combines power FETs, current sensor, and reverse blocking protection in a small 2mm × 2mm package
- Thermal Regulation : Automatically reduces charge current to maintain die temperature during high power operation
- Autonomous Operation : No microcontroller required for basic charging functions
- Safety Features : Includes battery temperature monitoring, charge safety timer, and reverse current protection
Limitations:
- Single-Cell Only : Limited to 4.2V Li-ion/Li-polymer batteries only
- Fixed Charge Voltage : No programmable charge voltage adjustment
- Maximum Input Voltage : 6.5V maximum limits compatibility with some higher-voltage adapters
- Package Thermal Constraints : The small QFN package requires careful thermal management for maximum current operation
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Thermal Management
*Problem:* Operating at maximum charge current (500mA) without proper thermal design causes thermal shutdown.
*Solution:* Implement thermal vias under the package, use copper pours on PCB layers, and consider reducing charge current in high ambient temperature environments.
Pitfall 2: Input Capacitor Selection
*Problem:* Using ceramic capacitors with insufficient voltage rating or high ESR causing stability issues.
*Solution:* Use 10μF, 10V X5R or X7R ceramic capacitor placed within 2mm of IN pin. Avoid Y5V dielectrics due to poor DC bias characteristics.
Pitfall 3: Battery Connection Issues
*Problem:* Long PCB traces between BAT pin and battery causing inaccurate termination voltage.
*Solution:* Keep BAT pin connection direct to battery terminal with minimal trace length and resistance.
### Compatibility Issues with Other Components
Microcontroller Interfaces:
- The STAT output is open-drain requiring external pull-up resistor (10kΩ to 100kΩ)
- TS pin requires negative temperature coefficient thermistor (103AT) for proper temperature monitoring
- Compatible with 1.8V and 3.3V logic levels for status monitoring
Power Management Integration:
- Works well with TI's TPS63000 series buck-boost converters for system power
- May require input overvoltage protection when used with automotive supplies
- Ensure system load doesn't exceed available current during charging
### PCB Layout Recommendations
Power Path Layout:
- Place input capacitor (C1) within 2mm of IN pin with short, wide traces
- Use star-point grounding for power and analog grounds
- Keep BAT pin
