LVR040S

Due to market price fluctuations, if you need to purchase or consult the price. You can contact us or emial to us:   sales@allicdata.com

PTC Resettable Fuses are an essential component in many electrical circuits. The devices provide a self-protection mechanism in case of power overload, that requires resetting after the incident. Typical designs are fuses that detect and react to excessively high current flow, resetting the circuit when the overcurrent stops. Among the leading players in the PTC Resettable Fuses design and manufacturing market is Littelfuse, offering the LVR040S solution. In this article, we will review the design parameters of the device, as well as its application field and working principle.

Design Parameters

The LVR040S PTC Resettable Fuses from Littelfuse is a polymeric positive temperature coefficient (PPTC) resettable device. It can act as an overcurrent and overtemperature protection device, providing a high degree of safety to equipment and users. It is available as radial leaded components with the following basic characteristics:

• Rated voltage: 28V
• Rated current: 40A
• Maximum operating temperature: 85°C
• Hold current range: 25A to 10A
• Trip current range: 10A to 4A
• Maximum trip time: 350ms
• UL94V-0 approved/RoHS compliant

The device is encapsulated in a solder resistant thermoplastic material, of dimensions 8.5 × 10.5mm​, and weighing only 6.81g.

Application Field

Due to its design parameters, the LVR040S is the ideal protection device when current overloads up to 40A are expected. Its small size and weight make it ideally suited for applications where space considerations are important, such as battery operated consumer electronics. It is also an ideal solution for power supplies, adapters, and motor control and automotive applications. The device can be mounted on a PCB or used as a free-standing component.

The LVR040S can be used in combination with other Littelfuse products for higher maximum current requirements or additional protection requirements. As an example, for applications with a current up to 60A, the LVR060S device can be combined with a Littelfuse’s PPC15P cartridge fuse.

Working Principle

At normal power operations, the LVR040S device presents a low resistance path and allows current to pass freely while maintaining an almost constant voltage drop. When current through the device exceeds the rated current, the device enters its protection mode and its resistance increases exponentially. This decrease in current flow and resulting power dissipated can protect an equipment from catastrophic failure due to overcurrents.

Once the overcurrent is removed, the device will reset itself within a few seconds and reestablish the circuit operation, as long as the temperature was below the maximum trip temperature. This process is called auto-recovery, and it is the outstanding feature of the LVR040S. The PTC element contains a crystallized pressure-sensitive material suspended in a thermoplastic binder, forming a two-terminal junction.

When the device is subjected to a current flow, the pressure-sensitive material melts, and the electrical resistance of the device increases. Once the applied current is removed, the pressure-sensitive material returns to a solid state, and the device\'s resistance becomes very low. This resetting process is essential for the device’s protection function, allowing it to be reused in case of another overcurrent scenario.

Conclusion

The LVR040S PTC Resettable Fuse from Littelfuse is designed to provide an effective protection against overcurrent and overtemperature scenarios. It presents excellent features and characteristics for industrial applications, including a maximum rated current of 40A, fast acting time and self-resetting capabilities. The device can be mounted on a PCB or used as a single component, and can be combined with other Littelfuse solutions for higher maximum current requirements.

The specific data is subject to PDF, and the above content is for reference