3-Pin Microprocessor Power Supply Supervisors # CAT803RTBIGT3 Technical Documentation
## 1. Application Scenarios
### Typical Use Cases
The CAT803RTBIGT3 is a microprocessor (μP) supervisory circuit primarily employed in systems requiring reliable power monitoring and reset control. Key applications include:
- Power-On Reset Generation : Provides a controlled reset pulse during system power-up, ensuring proper microcontroller initialization
- Brown-Out Detection : Monitors supply voltage and asserts reset when voltage drops below specified threshold (2.93V typical)
- Manual Reset Control : Incorporates a manual reset input for system debugging and user-initiated resets
- Battery-Powered Systems : Low quiescent current (5μA typical) makes it suitable for portable and battery-operated devices
### Industry Applications
- Consumer Electronics : Smart home devices, IoT sensors, wearable technology
- Industrial Control Systems : PLCs, motor controllers, automation equipment
- Automotive Electronics : Infotainment systems, body control modules, telematics
- Medical Devices : Portable monitoring equipment, diagnostic tools
- Telecommunications : Network equipment, base stations, routers
### Practical Advantages and Limitations
Advantages:
- High Accuracy : ±1.5% reset voltage threshold accuracy ensures reliable operation
- Low Power Consumption : 5μA typical supply current extends battery life
- Small Form Factor : SOT-23-5 package saves board space
- Wide Temperature Range : -40°C to +85°C operation suitable for harsh environments
- Immediate Response : No delay capacitors required for basic operation
Limitations:
- Fixed Threshold : Limited to specific voltage options (CAT803RTBIGT3: 2.93V)
- No Watchdog Timer : Lacks additional monitoring features found in more complex supervisors
- Limited Reset Timeout : Fixed 140ms minimum reset pulse width
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Insufficient Bypassing
- Issue : Noise on VCC causing false resets
- Solution : Place 0.1μF ceramic capacitor within 10mm of VCC pin
Pitfall 2: RESET Output Loading
- Issue : Excessive capacitive loading causing timing violations
- Solution : Limit load capacitance to 50pF maximum; use buffer for heavy loads
Pitfall 3: Manual Reset Debouncing
- Issue : Mechanical switch bounce triggering multiple resets
- Solution : Implement hardware debouncing (RC filter) or software debouncing
Pitfall 4: Ground Bounce Issues
- Issue : Poor ground connection affecting threshold accuracy
- Solution : Use solid ground plane and minimize ground return path length
### Compatibility Issues with Other Components
Microcontroller Interfaces:
- Compatible with most 3V microcontrollers (ARM Cortex-M, PIC, AVR)
- Ensure RESET output voltage levels match microcontroller requirements
- Verify reset polarity compatibility (CAT803 provides active-low reset)
Power Supply Considerations:
- Works with LDO regulators and switching converters
- Monitor supply ripple; excessive noise may trigger false resets
- Consider power sequencing requirements in multi-rail systems
Mixed Voltage Systems:
- Not suitable for direct 5V system interfacing without level translation
- RESET output follows VCC; ensure compatible with connected devices
### PCB Layout Recommendations
Power Distribution:
- Use star-point grounding for analog and digital sections
- Route VCC trace directly from power supply bypass capacitor
- Maintain continuous ground plane beneath the device
Component Placement:
- Position CAT803 close to the monitored microcontroller
- Keep bypass capacitor within 5mm of VCC pin
- Route MR (Manual Reset) traces away from noisy signals
Signal
