Driver Side Protection # CD143ASR70 Technical Documentation
*Manufacturer: BOURNS*
## 1. Application Scenarios
### Typical Use Cases
The CD143ASR70 is a high-performance current sense resistor primarily employed in power management systems and current monitoring applications . Typical implementations include:
- Motor control systems in industrial automation and robotics
- Battery management systems (BMS) for electric vehicles and energy storage
- Power supply current monitoring in server racks and telecom equipment
- Overcurrent protection circuits in consumer electronics and industrial controls
### Industry Applications
- Automotive Electronics : EV/HEV traction inverters, battery monitoring, charging systems
- Industrial Automation : Servo drives, PLCs, motor controllers, welding equipment
- Renewable Energy : Solar inverters, wind turbine converters, grid-tie systems
- Telecommunications : Base station power amplifiers, server power distribution
- Consumer Electronics : High-power audio amplifiers, gaming consoles, high-end PCs
### Practical Advantages and Limitations
Advantages:
- Low TCR (Temperature Coefficient of Resistance) : ±70 ppm/°C ensures stable performance across temperature variations
- High power rating : 7W capability supports demanding applications
- Excellent thermal stability : Metal strip construction minimizes thermal EMF
- Low inductance : <10 nH design suitable for high-frequency applications
- Four-terminal Kelvin connection : Eliminates measurement errors from contact resistance
Limitations:
- Size constraints : 7343 package (7.3mm × 4.3mm) may be large for space-constrained designs
- Cost considerations : Higher precision than standard resistors increases unit cost
- Mounting requirements : Requires precise PCB layout for optimal performance
- Limited resistance range : Specific to current sensing applications (typically milliohm range)
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Inadequate Power Derating
- Issue : Operating at full 7W rating without proper thermal management
- Solution : Implement 50-70% power derating based on ambient temperature and airflow
Pitfall 2: Poor Kelvin Connection Implementation
- Issue : Incorrect routing of sense traces leading to measurement errors
- Solution : Use separate, dedicated traces for current-carrying and sense connections
Pitfall 3: Thermal Management Neglect
- Issue : Overheating due to insufficient copper area or poor ventilation
- Solution : Provide adequate thermal relief and consider heatsinking for high-current applications
### Compatibility Issues with Other Components
Amplifier Interface:
- Ensure differential amplifier common-mode voltage range matches application requirements
- Verify amplifier input offset voltage compatibility with small voltage drops
ADC Considerations:
- Match resistor voltage output to ADC input range
- Consider noise filtering requirements for high-resolution measurements
Power Supply Compatibility:
- Verify voltage isolation requirements in high-side current sensing
- Ensure proper level shifting when interfacing with low-voltage logic
### PCB Layout Recommendations
Thermal Management:
- Use minimum 2 oz copper thickness for power traces
- Implement thermal relief vias to inner ground planes
- Provide adequate copper area (≥100 mm²) for heat dissipation
Signal Integrity:
- Route sense traces as differential pairs with controlled impedance
- Keep sense traces away from high-frequency switching nodes
- Use ground planes for noise shielding
Placement Guidelines:
- Position close to current source to minimize trace resistance
- Maintain minimum 2mm clearance from other heat-generating components
- Orient parallel to airflow for optimal cooling
Kelvin Connection Implementation:
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Power Trace ───┐ ┌─── To Load
│ │
┌───┼────┼───
