2920L Series # Technical Documentation: 2920L050DR PTC Resettable Fuse
Manufacturer : LITTELFUSE
Component Type : Polymeric Positive Temperature Coefficient (PTC) Resettable Fuse
Rated Voltage : 50V DC
Hold Current : 2.0A
Trip Current : 4.0A
## 1. Application Scenarios
### Typical Use Cases
The 2920L050DR serves as an autonomous overcurrent protection device in low-voltage DC circuits. Its primary function involves safeguarding sensitive electronic components from excessive current flow while maintaining operational continuity through automatic reset capabilities.
Primary Applications:
- Circuit Protection : Automatically interrupts current flow during overcurrent events (2.0A hold, 4.0A trip) and resets when fault conditions clear
- Load Monitoring : Continuously monitors current levels without requiring manual intervention or replacement
- Fault Containment : Limits current to safe levels during short-circuit conditions, typically reducing current to <0.4A at rated voltage
### Industry Applications
Consumer Electronics:
- USB power ports and charging circuits in smartphones, tablets, and portable devices
- LCD/LED display backlight protection
- Computer peripherals (keyboards, mice, external storage)
- Gaming consoles and entertainment systems
Automotive Electronics:
- Infotainment systems and dashboard displays
- Power window and seat control modules
- LED lighting circuits and accessory power outlets
- ECU protection in non-critical systems
Industrial Control Systems:
- PLC I/O module protection
- Sensor network power distribution
- Low-power motor control circuits
- Instrumentation and measurement equipment
Telecommunications:
- Router and switch power circuits
- Network interface devices
- Base station auxiliary power systems
### Practical Advantages and Limitations
Advantages:
- Automatic Reset : Eliminates maintenance requirements and replacement costs after fault clearance
- Fast Response Time : Typical trip time of <1.0 second at 8A overload conditions
- Compact Form Factor : 2920 package size (7.2mm × 5.1mm) enables high-density PCB layouts
- Wide Temperature Range : Operational from -40°C to +85°C ambient temperature
- Zero Power Consumption : No quiescent current draw in normal operating state
Limitations:
- Voltage Dependency : Maximum interrupt rating decreases with increasing voltage
- Thermal Sensitivity : Trip characteristics vary with ambient temperature (-20% to +80% tolerance across temperature range)
- Resistance Degradation : Initial resistance of 0.05Ω may increase up to 4× after multiple trip cycles
- Recovery Time : Requires 1-60 seconds to reset depending on cooling conditions and fault severity
## 2. Design Considerations
### Common Design Pitfalls and Solutions
Pitfall 1: Thermal Coupling with Heat-Generating Components
- Issue : Proximity to power ICs, regulators, or transformers causes premature tripping
- Solution : Maintain minimum 5mm clearance from heat sources and provide adequate ventilation
Pitfall 2: Inadequate Current Headroom
- Issue : Designing too close to hold current rating (2.0A) causes nuisance tripping during normal operation
- Solution : Derate to 70-80% of hold current (1.4-1.6A maximum continuous current)
Pitfall 3: Parallel Connection Attempts
- Issue : Attempting to increase current rating by paralleling multiple PTCs
- Solution : Use single appropriately rated device; parallel connection creates current imbalance
Pitfall 4: AC Circuit Misapplication
- Issue : Using DC-rated PTC in AC applications
- Solution : Verify application matches 50V DC
