500mA Variable/Fixed Output LDO Regulators Built-in thermal shutdown circuit # Technical Documentation: BD12KA5WFE2 Voltage Regulator
Manufacturer : ROHM Semiconductor
## 1. Application Scenarios
### Typical Use Cases
The BD12KA5WFE2 is a 1.2A output current, 36V input voltage LDO regulator designed for applications requiring stable power supply with low dropout voltage. Typical implementations include:
- Embedded Systems : Power management for microcontrollers, DSPs, and FPGAs in industrial control systems
- Automotive Electronics : Infotainment systems, body control modules, and sensor interfaces requiring stable 3.3V or 5V rails
- IoT Devices : Battery-powered applications where extended operation and thermal management are critical
- Industrial Automation : PLCs, motor drivers, and measurement equipment operating in harsh environments
### Industry Applications
- Automotive : Compliant with AEC-Q100 standards for automotive qualification
- Industrial Control : Suitable for factory automation, process control systems
- Consumer Electronics : Smart home devices, portable electronics
- Telecommunications : Base station equipment, network infrastructure
### Practical Advantages and Limitations
Advantages:
- High Input Voltage Tolerance : Maximum 36V input voltage capability
- Low Dropout Voltage : 0.5V typical at 1A load current
- Thermal Protection : Built-in thermal shutdown at 150°C typical
- Current Limiting : Overcurrent protection with foldback characteristics
- Compact Package : HTSOP-J8 package with excellent thermal characteristics
Limitations:
- Power Dissipation : Maximum power dissipation of 2W requires careful thermal management
- Efficiency : Lower efficiency compared to switching regulators at high input-output differentials
- Output Current : Limited to 1.2A maximum continuous current
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Thermal Management Issues
- Pitfall : Inadequate heatsinking leading to thermal shutdown
- Solution : Implement proper PCB copper area (minimum 30mm²) and consider additional heatsinking for high ambient temperatures
Input Voltage Transients
- Pitfall : Voltage spikes exceeding 36V absolute maximum rating
- Solution : Include TVS diodes or input capacitors with sufficient voltage rating
Stability Problems
- Pitfall : Oscillation due to improper output capacitor selection
- Solution : Use recommended 10μF ceramic capacitor with ESR between 10mΩ and 1Ω
### Compatibility Issues with Other Components
Microcontroller Interfaces
- Ensure output voltage matches processor core voltage requirements (typically 3.3V or 5V variants available)
- Consider power sequencing requirements when used with multiple voltage rails
Sensor Integration
- Verify noise sensitivity of analog sensors; additional filtering may be required
- Ensure load transient response meets sensor power requirements
Power Supply Chain
- Compatible with upstream switching regulators and battery management systems
- May require pre-regulation for input voltages above 36V
### PCB Layout Recommendations
Power Path Layout
- Use wide traces for input and output paths (minimum 40 mil width for 1A current)
- Place input capacitor (CIN) within 5mm of VIN pin
- Position output capacitor (COUT) close to VOUT pin
Thermal Management
- Utilize large copper pours connected to thermal pad
- Include multiple thermal vias under the package
- Maintain minimum 2mm clearance from heat-sensitive components
Grounding Strategy
- Implement star grounding at device GND pin
- Separate analog and digital ground planes if used in mixed-signal systems
- Ensure low-impedance return paths for bypass capacitors
## 3. Technical Specifications
### Key Parameter Explanations
Electrical Characteristics (TA = 25°C, VIN = 14
