SINGLE-CHIP CHARGE AND SYSTEM POWER-PATH MANAGEMENT IC (bqTINYI)# BQ24035RHLR Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The BQ24035RHLR is a highly integrated single-chip Li-ion and Li-polymer battery charge management controller designed for space-limited portable applications. Typical use cases include:
- Portable Medical Devices : Insulin pumps, portable monitors, and wearable health trackers requiring reliable battery charging with safety features
- Consumer Electronics : Smartphones, tablets, digital cameras, and portable gaming devices needing compact charging solutions
- Industrial Handhelds : Barcode scanners, portable data terminals, and measurement instruments requiring robust charging capabilities
- Wearable Technology : Smartwatches, fitness trackers, and IoT devices where board space is extremely limited
- Portable Audio Equipment : Wireless speakers, headphones, and audio recording devices
### Industry Applications
- Healthcare : Medical monitoring equipment requiring precise charge termination and thermal protection
- Automotive : Infotainment systems and portable navigation devices with USB charging capabilities
- Telecommunications : Mobile routers, portable hotspots, and communication devices
- Consumer Electronics : Mass-market portable devices requiring cost-effective charging solutions
- Industrial Automation : Handheld controllers and portable test equipment
### Practical Advantages and Limitations
Advantages:
- High Integration : Combines power FETs, current sensor, and reverse blocking protection in a single package
- Compact Footprint : 3mm × 3mm QFN package ideal for space-constrained designs
- Flexible Input Sources : Supports USB and adapter inputs with automatic detection
- Thermal Regulation : Maintains optimal charge current based on die temperature
- Safety Features : Includes battery temperature monitoring, charge timer, and overvoltage protection
Limitations:
- Fixed Charge Voltage : Limited to 4.2V typical charge voltage (not adjustable)
- Current Handling : Maximum 1.5A charge current may be insufficient for high-capacity batteries
- Temperature Range : Operating range of -40°C to +85°C may not suit extreme environment applications
- Package Thermal : QFN package requires careful thermal management for maximum performance
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Thermal Management
- Problem : Overheating during high-current charging leading to thermal shutdown
- Solution : Ensure proper thermal vias under the package and adequate copper area for heat dissipation
Pitfall 2: Input Source Compatibility Issues
- Problem : Incorrect detection of USB vs. adapter input sources
- Solution : Properly configure TS and ISET2 pins according to application requirements
Pitfall 3: Battery Connection Problems
- Problem : Intermittent battery connection causing charge cycle resets
- Solution : Implement robust battery connector design and include proper decoupling
Pitfall 4: PCB Layout Induced Noise
- Problem : Switching noise affecting sensitive analog circuits
- Solution : Separate analog and power grounds, use proper filtering on sensitive pins
### Compatibility Issues with Other Components
Power Management ICs:
- Ensure compatible voltage levels with system PMICs
- Verify sequencing requirements with system power rails
Microcontrollers:
- STAT and PG outputs compatible with 3.3V logic levels
- Ensure proper pull-up/pull-down resistors for open-drain outputs
Battery Protection Circuits:
- Compatible with standard Li-ion protection ICs
- Ensure protection IC doesn't interfere with charge termination detection
USB Controllers:
- USB input detection compatible with USB 2.0/3.0 specifications
- Proper ESD protection required on USB input lines
### PCB Layout Recommendations
Power Section Layout:
- Place input capacitors (C1, C2) as close as possible to IN and
