500mA Variable/Fixed Output LDO Regulators Built-in thermal shutdown circuit # Technical Documentation: BD25KA5FPE2
Manufacturer : ROHM
Component Type : 2.5V Voltage Detector IC with Watchdog Timer
## 1. Application Scenarios
### Typical Use Cases
The BD25KA5FPE2 is primarily employed in microcontroller-based systems requiring reliable power monitoring and system reset functionality. Typical implementations include:
- Power-on Reset Circuits : Ensures microcontroller initialization at proper voltage levels during system startup
- Brown-out Protection : Monitors supply voltage during operation and triggers reset when voltage drops below threshold
- Watchdog Timer Applications : Provides system supervision by requiring periodic "heartbeat" signals from the host microcontroller
- Battery-powered Systems : Monitors battery voltage to prevent unstable operation during discharge cycles
### Industry Applications
Automotive Electronics :
- Engine control units (ECUs)
- Infotainment systems
- Advanced driver assistance systems (ADAS)
- Body control modules
Industrial Control Systems :
- Programmable logic controllers (PLCs)
- Motor drives
- Process automation equipment
- Safety-critical monitoring systems
Consumer Electronics :
- Smart home devices
- Wearable technology
- IoT edge devices
- Portable medical equipment
Telecommunications :
- Network switches and routers
- Base station equipment
- Communication modules
### Practical Advantages and Limitations
Advantages :
- High Accuracy : ±2% detection voltage tolerance ensures reliable operation
- Low Current Consumption : Typical 1.0μA standby current extends battery life
- Wide Operating Range : 1.6V to 6.0V supply voltage compatibility
- Integrated Watchdog : Eliminates need for external timing components
- Small Package : VSON008X2030 (2.0×2.0×0.6mm) saves board space
- Automotive Grade : AEC-Q100 qualified for harsh environments
Limitations :
- Fixed Detection Voltage : 2.5V threshold cannot be adjusted for different applications
- Limited Output Drive : RESET output sink current limited to 1mA
- Temperature Dependency : Detection voltage varies with temperature (typical ±0.5mV/°C)
- Discrete Component Requirement : May require external pull-up resistors depending on microcontroller interface
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Insufficient Bypass Capacitance
- Problem : Voltage spikes or noise triggering false resets
- Solution : Place 0.1μF ceramic capacitor within 5mm of VDD pin, with additional 1-10μF bulk capacitor for noisy environments
Pitfall 2: Watchdog Timer Misconfiguration
- Problem : System entering unexpected reset cycles
- Solution : Ensure watchdog timeout period matches application requirements; typical 1.6s timeout requires periodic toggling within this window
Pitfall 3: RESET Output Loading
- Problem : Excessive sink current damaging output stage
- Solution : Limit load current to specified maximum; use buffer for driving multiple loads
Pitfall 4: PCB Layout Issues
- Problem : Noise coupling affecting detection accuracy
- Solution : Keep high-speed digital traces away from detector inputs; use ground plane beneath device
### Compatibility Issues with Other Components
Microcontroller Interfaces :
- Compatible with 3.3V and 5V logic families
- Open-drain RESET output requires pull-up resistor (typically 10kΩ to 100kΩ)
- Ensure VDD levels match microcontroller supply requirements
Power Supply Considerations :
- Works with LDO regulators, switching converters, and battery sources
- Monitor startup and shutdown characteristics to ensure proper reset timing
- Consider supply sequencing in multi-rail systems
Mixed-Signal
