Surface Mountable Sound Generators CHB Series # CHB03M Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The CHB03M serves as a high-performance current sensing resistor in precision measurement applications. Its primary use cases include:
- Motor Control Systems : Provides accurate current feedback for BLDC and stepper motor drivers in industrial automation equipment
- Power Management Circuits : Enables precise current monitoring in DC-DC converters, battery management systems, and power supplies
- Overcurrent Protection : Functions as a sensing element in protection circuits for consumer electronics and automotive systems
- Energy Monitoring : Facilitates power consumption measurement in smart meters and IoT devices
### Industry Applications
Automotive Electronics
- Electric vehicle battery management systems (BMS)
- Automotive infotainment power monitoring
- LED lighting current regulation
Industrial Automation
- PLC input/output modules
- Servo drive current feedback
- Industrial robot power monitoring
Consumer Electronics
- Smartphone fast-charging circuits
- Laptop power adapters
- Gaming console power management
Renewable Energy
- Solar inverter current sensing
- Wind turbine power monitoring
### Practical Advantages and Limitations
Advantages:
- Low TCR (15 ppm/°C) : Maintains stable resistance across temperature variations
- High Power Rating (3W) : Suitable for high-current applications
- Excellent Long-Term Stability : <0.5% resistance drift over 2000 hours
- Low Inductance (<5 nH) : Minimizes impact in high-frequency applications
- AEC-Q200 Qualified : Meets automotive reliability standards
Limitations:
- Limited Current Handling : Maximum continuous current of 7A may require parallel configurations for higher current applications
- Thermal Management : Requires adequate PCB copper area for heat dissipation
- Cost Considerations : Higher precision comes at premium pricing compared to standard resistors
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Thermal Management
- Problem : Excessive temperature rise causing resistance drift and potential failure
- Solution : Implement proper thermal vias and sufficient copper pour (minimum 2 oz copper, 1.5 in² area)
Pitfall 2: Poor Placement Relative to Sensitive Circuits
- Problem : Thermal coupling affecting adjacent temperature-sensitive components
- Solution : Maintain minimum 5mm clearance from precision analog ICs and thermal isolation slots
Pitfall 3: Incorrect Kelvin Connection Implementation
- Problem : Voltage drop errors in sense lines due to improper routing
- Solution : Use dedicated sense traces directly from resistor pads to measurement IC
### Compatibility Issues with Other Components
Amplifier Interface Considerations
- Compatible : Most current sense amplifiers (INA210, INA240 series)
- Incompatible : High-input impedance amplifiers without proper filtering
- Recommendation : Use amplifiers with input common-mode range matching application voltage
ADC Integration
- Optimal Pairing : 16-bit or higher resolution ADCs for precision measurement
- Timing Considerations : Account for thermal settling time (typically 100ms) after current steps
### PCB Layout Recommendations
Power Routing
- Route high-current traces with minimum 50 mil width for 7A capacity
- Maintain symmetrical current path through resistor for balanced heating
Sense Line Routing
- Use Kelvin connections with dedicated sense traces
- Route sense lines as differential pairs to measurement IC
- Keep sense lines away from noisy digital signals
Thermal Management
- Implement thermal relief patterns with multiple vias to inner layers
- Use 2 oz copper thickness for power planes
- Consider solder mask opening over thermal pads for improved heat transfer
Placement Guidelines
- Position close to current measurement IC to minimize noise pickup
- Orient parallel to airflow in forced convection systems
