HXO RXF series thermal fuse resistor integrates over-temperature and over-current protection in one component. Ceramic body + alloy thermal fuse in a unified package, with 221℃ precise action temperature, providing ultimate safety protection for power products.
During the production of phone chargers and power adapters, shell melting is a common safety hazard. The thermal fuse resistor automatically breaks the circuit when abnormal temperature reaches 221°C, preventing shell deformation and fire risk. CQC/UL certified, meeting charger manufacturers' safety requirements. One component, dual protection — over-temperature + over-current, safeguarding your product safety.
HXO RXF series thermal fuse resistor integrates a wire-wound fuse resistor and an alloy thermal fuse in a unified package, offering both over-temperature protection and over-current protection. When the PCB temperature abnormally rises to 221℃, the thermal fuse automatically blows,disconnects the circuit to prevent fire hazards. One component, dual protection.
| Parameter | Specification | Remarks |
|---|---|---|
| Model | HXO-RXF-1W12-221 | Vertical K-tape packaging |
| Product Name | Thermal Fuse Resistor | RXF Series |
| Power | 1W | At 25℃ ambient temperature |
| Nominal Resistance | 12Ω | - |
| Resistance Tolerance | ±5% | Grade J |
| Action Temperature | 221℃ | Alloy thermal fuse |
| Holding Temperature | 170℃ | Max temperature without activation |
| Limit Temperature | 250℃ | - |
| Fusing Current | 0.86A | Fuses in ＜60s |
| Rated Voltage | 250V | AC/DC |
| Surge Withstand | 1.5kV | Per IEC-61000-4-5 |
| Body Size | Φ4.5×11.5mm | Including leads |
| Lead Diameter | Φ0.6±0.05mm | - |
| Operating Temperature | -55℃ ~ +125℃ | Working ambient temperature |
| Storage Conditions | 10~30℃, 30~70%RH | - |
Under fault conditions, thermal fuse resistors and ordinary resistors behave very differently. The comparison below shows why thermal fuse resistors are the superior choice for charger/adapter safety protection.
| Comparison Item | Ordinary Resistor | HXO RXF Thermal Fuse Resistor |
|---|---|---|
| Over-Temperature Protection | ❌ No protection. Resistance changes as temperature rises, but circuit is not disconnected,continuous heating causes PCB scorching and shell melting | ✅ Auto-fuse at 221℃. Alloy thermal fuse activates precisely, permanently disconnects the circuit, preventing further temperature rise |
| Over-Current Protection | ❌ No over-current protection. May burn open under high current, but no temperature threshold control, inconsistent fusing behavior | ✅ Dual protection. Integrated over-temperature + over-current protection, fusing current 0.86A (＜60s), precise and reliable |
| Post-Fault Status | ⚠️ May open, short, or change resistance — uncertain state. Some resistors remain conductive after burnout, posing safety risks | ✅ Permanent disconnection. Fuse completely blows, insulation resistance＞1000MΩ, ensuring full circuit isolation for guaranteed safety |
| Shell Melting Prevention | ❌ Cannot prevent shell melting. Continuous heating under fault, PCB temperature can reach 300℃+, shell deforms and melts, potentially causing fire | ✅ Active shell melting prevention. 221℃ action temperature is below shell material melting point (typically ABS 240℃/PC 260℃),disconnects the circuit before shell melts |
| Surge Withstand | ⚠️ Ordinary wire-wound resistors have limited surge capability; may break down or burn open under large surge voltage | ✅ 1.5kV surge withstand. Meets IEC-61000-4-5 standard, stable operation under grid fluctuations and lightning surges |
| Safety Certification | ❌ Typically no safety certification, or only basic flame retardant rating | ✅ CQC Certified. CQC22001342008 / CQC2018010205108105, meets charger safety compliance requirements |
| Safety Compliance Review | ❌ Protection schemes using ordinary resistors struggle to pass safety review (GB4943/UL60950), requiring additional thermal fuse components | ✅ Single component passes compliance. Thermal fuse resistor itself meets safety requirements for over-temperature protection, simplifying PCB design and review process |
| PCB Space | ⚠️ To achieve over-temperature protection, an additional thermal fuse must be added,occupying more PCB space and adding soldering steps | ✅ Space saving. One component achieves both current limiting + over-temperature protection, saving 30%+ PCB space, reducing soldering steps |
| Total Cost | ⚠️ Single resistor cost is low, but + extra fuse + labor + PCB space, total cost is higher | ✅ Lower total cost. One replaces two, reducing BOM item count and soldering steps, total cost reduced by 20-30% |
One component provides both over-temperature and over-current protection, simplifying PCB design, saving space and cost
Wire-wound fuse resistor + alloy thermal fuse in a unified package, compact structure with high reliability
CQC22001342008 / CQC2018010205108105, RoHS/REACH compliant, safety compliance assured
Meets IEC-61000-4-5 standard, adapts to grid fluctuation environments, lightning surge protection
Complete technical specifications including electrical characteristics, dimensions, temperature curves, and reliability data.
Download PDFFull product series specifications, comparison tables, and selection guide.
Download PDFCQC certificates, RoHS/REACH compliance declarations, patent certificates.
View CertificationsAn ordinary resistor only provides current limiting/voltage dividing functions. A thermal fuse resistor integrates a thermal fuse on top of the ordinary resistor — when the ambient temperature exceeds the set value (221℃), it automatically fuses and disconnects the circuit. It also provides over-current protection, achieving dual protection in a single component.
The action temperature (221℃) is the critical temperature at which the internal fuse of the thermal fuse resistor blows. When the ambient temperature reaches 221℃, the fuse blows within 60 seconds, permanently disconnecting the circuit. The holding temperature (170℃) is the maximum temperature at which no false activation occurs — normal long-term operation is guaranteed below 170℃.
Yes, the thermal fuse resistor is a one-time protection component. Once the action temperature is reached and the fuse blows, it cannot be restored and requires replacement. This is the fundamental difference from PTC (resettable) devices. The one-time design ensures absolute reliability of the protection action, without performance degradation from repeated activations.
Thermal fuse resistors are widely used in phone chargers (7.5W+ fast charging), power adapters, switching power supplies (SMPS), LED drivers, industrial power supplies, home appliance control boards, communication equipment, power tools, and more. Any electronic product with PCB over-temperature protection needs can benefit from thermal fuse resistors.
The 221℃ action temperature falls under high-temperature protection and is particularly suitable for: ① Fast charging chargers/adapters (high power density leads to higher temperature rise); ② Switching power supplies (MOSFET and other components can reach 150℃+); ③ LED drivers (cumulative temperature rise from long operation); ④ Industrial power supplies (high ambient temperature combined with self-heating). The 221℃ setting ensures no false activation within normal operating temperature range while providing timely disconnection under abnormal overheating.
Shell melting in phone chargers is typically caused by: ① Component failure (e.g., MOSFET short circuit, transformer saturation) causing excessive heat generation; ③ Poor heat dissipation design leading to heat accumulation; ④ Prolonged high-load operation exceeding thermal design limits. When internal temperature exceeds the shell material's melting point (typically 240℃ for ABS), the shell deforms and melts, posing fire and electric shock risks.
The thermal fuse resistor is installed at critical positions on the PCB. When abnormal conditions cause temperature to rise, the thermal fuse resistor detects the temperature change at 221℃ and automatically fuses, disconnecting the circuit. This cuts off the heat source before the shell temperature reaches its melting point, preventing shell deformation and fire hazards. It provides proactive protection rather than reactive response.
This product has obtained CQC certification (CQC22001342008 / CQC2018010205108105), complies with RoHS and REACH environmental standards, and is designed per IEC 60691. It also has Chinese invention patent (ZL201520178319.3) and utility model patent (ZL202021302713.0) protection. The product meets the safety compliance requirements for phone chargers, power adapters, and other power products.
The 221℃ action temperature is ideal for high-temperature protection scenarios: ① Fast charging adapters where high power density causes significant temperature rise; ② Switching power supplies with high-temperature components like MOSFETs (150℃+); ③ LED drivers operating continuously for extended periods; ④ Industrial power supplies in high-temperature environments. The 221℃ threshold ensures no nuisance tripping under normal operation while providing reliable protection during abnormal overheating.
An OTP (Over-Temperature Protection) resistor like the RXF series integrates a thermal fuse mechanism with a resistor in a single package, responding to both temperature and current. An ordinary fuse resistor (fuse resistor) typically only responds to over-current conditions. The key difference is that the OTP resistor provides temperature-based protection — it cuts off the circuit when ambient temperature reaches the threshold, regardless of current level. This makes it particularly effective for preventing catastrophic failures caused by overheating, such as shell melting in chargers and adapters.
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