VOLTAGE PROTECTION FOR 2-, 3-, OR 4-CELL Li-Ion BATTERIES (2nd-LEVEL PROTECTION) # BQ29410PWG4 Technical Documentation
Manufacturer : TEXAS INSTRUMENTS
## 1. Application Scenarios
### Typical Use Cases
The BQ29410PWG4 is a highly integrated secondary overvoltage protection IC designed primarily for lithium-ion battery packs. Its main application scenarios include:
- 2-4 Series Cell Battery Packs : Provides precise overvoltage detection and protection for 2, 3, or 4 series-connected lithium-ion cells
- Battery Management Systems (BMS) : Serves as a secondary protection layer in conjunction with primary protection ICs
- Power Tool Battery Packs : Ensures safe operation in high-current discharge applications
- Portable Medical Equipment : Provides critical safety protection for life-sustaining devices
- Consumer Electronics : Used in laptops, power banks, and high-end portable devices requiring robust battery protection
### Industry Applications
- Automotive : Electric vehicle battery packs, 48V mild-hybrid systems
- Industrial : UPS systems, industrial handheld devices, backup power supplies
- Telecommunications : Base station backup batteries, portable communication equipment
- Renewable Energy : Solar energy storage systems, portable power stations
### Practical Advantages and Limitations
Advantages:
- High Accuracy : ±25mV overvoltage detection threshold accuracy across temperature range
- Low Power Consumption : Typical standby current of 3.5μA extends battery life
- Fast Response Time : Detection delay of approximately 1ms prevents cell damage
- Integrated MOSFET Drivers : Directly drives external protection MOSFETs
- Wide Voltage Range : Operates from 4V to 25V, suitable for various battery configurations
Limitations:
- Fixed Thresholds : Overvoltage thresholds are factory-set and not user-adjustable
- Secondary Protection Only : Requires primary protection IC for complete battery safety
- Temperature Dependency : Performance variations occur at extreme temperatures (-40°C to +85°C)
- External Components Required : Needs external MOSFETs and passive components for full functionality
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Incorrect Cell Balancing
- Issue : Without proper cell balancing, the BQ29410 may trigger false overvoltage protection
- Solution : Implement active or passive cell balancing circuitry to maintain voltage equilibrium
Pitfall 2: Inadequate MOSFET Selection
- Issue : Using MOSFETs with insufficient current handling capability or high RDS(on)
- Solution : Select MOSFETs with current rating exceeding maximum load current and low RDS(on) for efficiency
Pitfall 3: Poor Noise Immunity
- Issue : Electrical noise causing false triggering of protection circuits
- Solution : Implement proper filtering on sense lines and use bypass capacitors close to IC pins
### Compatibility Issues with Other Components
Primary Protection ICs:
- Compatible with most primary protection ICs like BQ29700 series
- Ensure communication protocols and timing align between primary and secondary protection
Microcontrollers:
- Status output can interface directly with microcontroller GPIO pins
- May require level shifting if microcontroller operates at different voltage levels
Charging Circuits:
- Compatible with various battery charger ICs
- Ensure charger disable function properly interfaces with protection circuit
### PCB Layout Recommendations
Power Routing:
- Use wide traces for battery cell connections (minimum 20 mil width for 2A current)
- Keep high-current paths as short as possible to minimize voltage drop
Signal Integrity:
- Route sense lines away from switching nodes and high-frequency signals
- Implement guard rings around sensitive analog inputs
Thermal Management:
- Provide adequate copper pour for heat dissipation
- Place thermal vias under the package for improved thermal performance
Component Placement
