Secondary Over-Voltage Protection for 2-4 cell in series Li-Ion/Poly (4.35V) 8-TSSOP -40 to 110# BQ29410PWR Technical Documentation
*Manufacturer: Texas Instruments (TI)*
## 1. Application Scenarios
### Typical Use Cases
The BQ29410PWR is a secondary overvoltage protector IC specifically designed for 2-series to 4-series lithium-ion/polymer battery packs . Its primary function is to monitor individual cell voltages and provide protection against overvoltage conditions that could damage batteries or connected systems.
Primary applications include:
- Portable Electronics : Smartphones, tablets, and laptops requiring reliable battery protection
- Power Tools : Cordless drills, saws, and other high-drain applications
- Medical Devices : Portable medical equipment where battery safety is critical
- UPS Systems : Uninterruptible power supplies with lithium battery backup
- E-mobility : Electric scooters, e-bikes, and small EV applications
### Industry Applications
- Consumer Electronics : Provides secondary protection in devices with high-capacity batteries
- Industrial Equipment : Ensures battery safety in harsh environmental conditions
- Automotive Accessories : Used in aftermarket automotive electronics with lithium batteries
- Energy Storage : Small-scale energy storage systems and solar-powered applications
### Practical Advantages
Strengths:
- High Accuracy : ±25mV overvoltage detection threshold accuracy
- Low Power Consumption : Typically 4μA in normal operation, 1μA in shutdown mode
- Fast Response Time : 1ms typical detection delay
- Compact Package : TSSOP-14 package saves board space
- Wide Voltage Range : Supports 2-4 series cell configurations (8V-16V)
Limitations:
- Secondary Protection Only : Requires primary protection IC for complete battery safety
- Limited to 4 Cells : Not suitable for larger battery packs exceeding 4 series cells
- Temperature Sensitivity : Performance may vary significantly outside -40°C to +85°C range
- External Components Required : Needs external MOSFETs for complete protection circuit
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Incorrect Threshold Setting
- Problem : Setting OV thresholds too close to normal operating voltage
- Solution : Maintain adequate margin (typically 100-200mV above maximum charge voltage)
Pitfall 2: Poor Transient Response
- Problem : False triggering during load transients
- Solution : Implement proper filtering on VDD pin and use recommended delay capacitors
Pitfall 3: Thermal Management
- Problem : Inadequate heat dissipation in high-current applications
- Solution : Use appropriate PCB copper pour and consider thermal vias
### Compatibility Issues
Component Compatibility:
- Primary Protection ICs : Compatible with most TI battery management ICs (e.g., BQ series)
- MOSFET Selection : Requires logic-level N-channel MOSFETs with appropriate VDS rating
- Microcontrollers : Standard open-drain output compatible with most MCUs
System Integration Challenges:
- Communication Protocols : No built-in communication interface; status monitoring requires external circuitry
- Power Sequencing : Ensure proper power-up sequence with primary protection circuit
- Fault Recovery : Manual reset required after protection triggering
### PCB Layout Recommendations
Critical Layout Guidelines:
1. Power Routing
- Use wide traces for battery connections (minimum 20mil width for 2A current)
- Place decoupling capacitors (100nF) close to VDD and VSS pins
2. Signal Integrity
- Route cell voltage sense lines away from noisy switching signals
- Use ground plane for noise reduction
- Keep protection output traces short to minimize inductance
3. Thermal Management
- Provide adequate copper area for heat dissipation
- Use thermal vias under
