Li-Ion Linear (4.1V & 4.2V) Charge Management IC For One-Cell Applications W/Integrated FET, Two LED# BQ24002PWPR Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BQ24002PWPR is a highly integrated single-chip Li-ion and Li-polymer battery charge management IC designed for space-limited portable applications. Key use cases include:
Primary Applications:
- Portable Medical Devices : Glucose meters, portable monitors, and wearable health trackers where reliable battery charging is critical
- Bluetooth Headsets & Wearables : Compact audio devices and fitness trackers requiring efficient power management
- Handheld Industrial Scanners : Barcode scanners and data collection devices used in logistics and retail environments
- Portable Consumer Electronics : Digital cameras, GPS devices, and handheld gaming systems
- IoT Edge Devices : Smart sensors and wireless modules requiring autonomous power management
### Industry Applications
Medical Sector :
- Advantages: Medical-grade reliability with thermal regulation and safety timers
- Limitations: Not suitable for life-critical medical equipment requiring redundant systems
Consumer Electronics :
- Advantages: Compact TSSOP package (20-pin) ideal for space-constrained designs
- Limitations: Maximum 1A charge current may be insufficient for high-capacity battery applications
Industrial Automation :
- Advantages: Robust operation across industrial temperature ranges (-40°C to +85°C)
- Limitations: Requires external components for complete power path management
### Practical Advantages and Limitations
Advantages:
- High Integration : Combines power FETs, current sensor, and reverse-blocking protection
- Thermal Regulation : Automatically reduces charge current to control die temperature
- Safety Features : Includes charge termination, timer, and temperature monitoring
- Input Voltage Range : Operates from 4.35V to 6.5V, compatible with various power sources
Limitations:
- Charge Current : Limited to 1A maximum, unsuitable for rapid charging applications
- Package Size : TSSOP-20 may require careful PCB layout in ultra-compact designs
- External Components : Requires external sense resistor and decoupling capacitors
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Thermal Management
- Issue : Excessive power dissipation in high-current applications
- Solution : Implement proper thermal vias under the package and ensure adequate copper area for heat sinking
Pitfall 2: Input Voltage Transients
- Issue : Unstable operation with noisy input power sources
- Solution : Add input capacitance (10µF ceramic close to VCC) and consider TVS diodes for surge protection
Pitfall 3: Battery Connection Problems
- Issue : Intermittent charging due to poor battery connector design
- Solution : Use robust battery connectors and implement proper strain relief
### Compatibility Issues with Other Components
Microcontroller Interfaces:
- The STAT and PG outputs are open-drain, requiring pull-up resistors when interfacing with MCUs
- Ensure MCU GPIO voltages are compatible with the IC's logic levels
Power Management Integration:
- Compatible with most DC-DC converters and LDOs
- Avoid connecting other charging circuits in parallel to prevent current contention
Battery Protection Circuits:
- Works well with standard Li-ion protection ICs
- Ensure protection IC cutoff voltage aligns with charger termination settings
### PCB Layout Recommendations
Power Path Routing:
- Use wide traces (≥20 mil) for BAT, VCC, and OUT pins
- Keep high-current paths short and direct to minimize IR drops
Component Placement:
- Place input capacitor (C1) within 2mm of VCC pin
- Position sense resistor (RSNS) close to SRP/SRN pins with Kelvin connection
- Keep thermal vias directly under the IC package for optimal heat dissipation
Grounding Strategy:
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