SMBus Controlled Battery Charger with Integrated FETs# BQ24765 Battery Charger IC Technical Documentation
*Manufacturer: Texas Instruments (TI)*
## 1. Application Scenarios
### Typical Use Cases
The BQ24765 is a synchronous battery charger IC designed for 2-4 cell series Li-ion and Li-polymer batteries, primarily targeting space-constrained portable electronics requiring high-efficiency charging solutions.
Primary Applications:
- Ultrabooks and Notebook Computers : Provides up to 10A charging current with 95% peak efficiency
- Portable Medical Devices : Supports medical-grade power management with precise charge termination
- Industrial Handheld Terminals : Enables rapid charging in field-deployable equipment
- High-End Tablets : Manages battery charging while supporting system power demands
- Robotics and Drones : Handles high-current charging for power-intensive mobile applications
### Industry Applications
Consumer Electronics
- Implements smart charging algorithms to extend battery lifecycle
- Supports USB Power Delivery when combined with appropriate controllers
- Enables fast charging (0°C to 45°C) and maintenance charging (-20°C to 60°C)
Industrial Systems
- Operates in extended temperature ranges (-40°C to 85°C)
- Withstands industrial power transients and noise environments
- Provides battery authentication support for safety-critical applications
Medical Equipment
- Meets medical safety standards with precise voltage/current regulation
- Supports redundant safety mechanisms for fault protection
- Enables predictable charging cycles for equipment reliability
### Practical Advantages and Limitations
Advantages:
- High Efficiency : 92-95% typical efficiency reduces thermal dissipation
- Flexible Input Sources : Supports 5-24V adapter input range
- Advanced Power Path Management : Allows system operation with absent/dead battery
- Integrated Protection : Includes over-voltage, over-current, and thermal shutdown
- Small Form Factor : 4mm × 4mm VQFN package saves board space
Limitations:
- External Component Count : Requires 6-8 external components for full implementation
- Battery Chemistry Specific : Optimized for Li-ion/Li-polymer only
- Maximum Current : Limited to 10A continuous charging current
- Thermal Management : Requires proper PCB thermal design at maximum currents
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Thermal Management
- Problem : Excessive junction temperature at full load reduces reliability
- Solution : Implement proper thermal vias, copper pours, and consider supplemental heatsinking
Pitfall 2: Input Voltage Transients
- Problem : Adapter plug/unplug events causing voltage spikes
- Solution : Use TVS diodes and ensure proper input capacitor selection (low ESR)
Pitfall 3: Battery Detection Issues
- Problem : Incorrect battery presence detection
- Solution : Proper pull-up/pull-down resistor values on detection pins
Pitfall 4: Charge Current Oscillation
- Problem : Unstable charging current due to poor compensation
- Solution : Follow TI's recommended compensation network values
### Compatibility Issues with Other Components
Power Management ICs (PMICs)
- Ensure proper sequencing with system PMICs to prevent back-powering
- Coordinate with fuel gauge ICs (e.g., TI's Impedance Track™ devices) for accurate state-of-charge
Microcontroller Interfaces
- I²C communication requires proper pull-up resistors (2.2kΩ typical)
- GPIO voltage levels must match host controller logic levels
External MOSFET Selection
- Critical parameters: RDS(ON) < 10mΩ, Qg < 30nC
- Ensure gate drive compatibility (5V typical)
### PCB Layout Recommendations
Power Stage Layout
- Place input capacitors
