Littelfuse Inc. 1206L350SLTHYR

Product Summary Littelfuse 1206L350SLTHYR PolySwitch Resettable PPTC

The Littelfuse 1206L350SLTHYR is a surface-mount PolySwitch® resettable polymeric positive temperature coefficient (PPTC) device, engineered for effective overcurrent protection in a compact footprint. Belonging to the Low Rho series, this model features a maximum voltage rating of 6V and a hold current of 3.5A, ideally suited for high-density electronic assemblies that require robust fault protection without sacrificing space. The 1206L350SLTHYR’s self-resetting nature enables designers to protect circuits from damage due to short circuits or overcurrent events without the need for manual fuse replacement, ensuring greater reliability and continuity in mission-critical and consumer applications alike.

Main Attributes and Advantages of the 1206L350SLTHYR Low Resistance Series

The Low Rho series, and specifically the 1206L350SLTHYR, introduce a suite of features that address the evolving demands of portable and high-efficiency electronics. This device is distinguished by its ultra-low internal resistance, which minimizes voltage drop during normal operation and supports higher hold currents within a reduced package size. The concave 1206 case (3.25mm x 1.65mm) conserves precious board real estate, while the device’s very thin profile facilitates dense layout schemes. Fast response to short circuit and overload currents enhances device and system safety. The 1206L350SLTHYR is compatible with high-temperature solder profiles, supporting modern lead-free, reflow, and wave soldering processes. Certified by UL and TUV, and compliant with RoHS and REACH, the fuse meets international standards for safety and environmental sustainability.

Electrical Characteristics and Physical Details of the 1206L350SLTHYR

Precision electrical characteristics define the 1206L350SLTHYR’s suitability for current-sensitive designs. It supports a maximum steady-state voltage of 6V, with a hold current up to 3.5A and a trip current of 7A. The device can withstand fault currents up to 50A, with a typical time-to-trip of 5 seconds, allowing it to quickly disconnect the protected circuit during overloads. Its initial resistance is as low as 3mΩ, rising to a maximum of 18mΩ after repeated tripping events, ensuring low power dissipation during normal operation. The footprint conforms to the 1206 (3216 metric) standard, with a maximum seated height of 0.75mm. The device maintains full functionality across -40°C to +85°C, supporting operation in a wide range of temperature environments.

Environmental Standards and Certification for the 1206L350SLTHYR

The Littelfuse 1206L350SLTHYR demonstrates best-in-class compliance with current environmental and safety directives. It is classified as RoHS3 compliant and is not affected by REACH regulations, making it suitable for use in global markets and environmentally sensitive applications. The device carries cURus and TUV recognition, facilitating streamlined design approvals for applications subject to international regulatory scrutiny. Its Moisture Sensitivity Level (MSL) rating of 1 further assures unlimited shelf life under proper storage, reducing supply chain concerns.

Use Cases for the 1206L350SLTHYR in Contemporary Electronic Devices

The 1206L350SLTHYR is optimized for modern, space-constrained electronic applications where resettable overcurrent protection is critical. Notable usage includes USB peripherals supporting USB 2.0 and 3.0 standards, where low-resistance protection devices prevent port damage without impeding data or power throughput. The part is also well suited for Li-ion and Li-polymer battery packs in smartphones, tablets, e-readers, and notebook PCs, offering a reliable safeguard against cell shorts and connector faults. Additional deployment areas include computer peripherals, digital cameras, external hard disk drives, smart TVs, and game consoles, all of which benefit from resettable and ultra-low resistance circuit protection.

Design Guidelines and Recommended Practices for Integrating the 1206L350SLTHYR

Proper selection and deployment of the 1206L350SLTHYR require attention to electrical and mechanical constraints. Engineers should verify that the device’s hold and trip currents are matched to their application's maximum in-rush and steady-state loads, taking temperature derating into account in elevated ambient environments. The small form factor presents advantages but requires appropriate thermal and spacing allowances, especially given the expansion behavior of PPTC devices during trip events. Rigid mounting or encapsulation that restricts this expansion should be avoided. The device is not recommended for applications with frequent or prolonged overcurrent conditions or with large circuit inductance, as voltage transients may exceed ratings. Careful PCB layout and solder profile selection, in conjunction with manufacturer guidance, will maximize device reliability.

Alternative or Substitute Parts for the Littelfuse 1206L350SLTHYR

When evaluating alternatives to the Littelfuse 1206L350SLTHYR, engineers may consider other Low Rho series models within the PolySwitch® family for variations in hold current, trip current, or footprint requirements. For example:

Littelfuse 0805L150SL: Optimized for applications requiring lower hold current in a smaller package.

Littelfuse 1206L150SL: Suited for similar voltage environments with lower hold current demands; frequently used for USB port protection.

Littelfuse 1812L350SL: Offers higher voltage or mounting options where board space is less constrained.

Littelfuse 2920L700SL: Ideal for high-current battery pack protection in larger devices like tablets.

Selection between these models should align with the voltage, current, and footprint specifics of the application. Cross-referencing with other manufacturers’ offerings is also possible, provided equivalent electrical and safety performance is verified.

Conclusion

The Littelfuse 1206L350SLTHYR Low Rho series PolySwitch® resettable PPTC fuse represents an advanced solution for engineers prioritizing compact form factor, ultra-low resistance, and robust overcurrent protection. Thorough understanding of its specifications, integration practices, and available series alternatives can ensure optimal device selection and system-level reliability for a wide spectrum of next-generation electronics. This makes the 1206L350SLTHYR an attractive choice for application engineers and procurement professionals seeking to enhance safety and device longevity without sacrificing space or efficiency.