The **MF-R110-0-99** is a popular electronic component manufactured by **Bourns**. It belongs to the family of **Multifuse® Polymer PTC (Positive Temperature Coefficient)** resettable fuses. --- ## 1. Core Functionality Unlike a traditional fuse that "blows" and must be replaced, the MF-R110 is **resettable**. * **Normal State:** It has low resistance and allows current to flow. * **Fault State:** If an overcurrent or overtemperature event occurs, the internal polymer heats up, causing its resistance to increase exponentially. This effectively "opens" the circuit. * **Recovery:** Once the fault is removed and the device cools down, it returns to a low-resistance state. --- ## 2. Technical Specifications The part number follows a specific nomenclature. Here are the key electrical characteristics for the **MF-R110**: | Parameter | Value | Description | | :--- | :--- | :--- | | **$I_{hold}$** | 1.10 Amps | The maximum current the device will hold without tripping. | | **$I_{trip}$** | 2.20 Amps | The minimum current at which the device is guaranteed to trip. | | **$V_{max}$** | 60 Volts | The maximum voltage the device can withstand without damage. | | **$I_{max}$** | 40 Amps | The maximum fault current the device can safely interrupt. | | **$P_{d}$** | 1.5 Watts | Power dissipated when the device is in a tripped state. | | **Resistance ($R_{min}/R_{1max}$)** | 0.15 - 0.38 $\Omega$ | The resistance range of the device at $23^\circ C$. | --- ## 3. Physical Attributes & Part Suffixes The "-0-99" suffix provides specific details regarding the physical form and packaging: * **MF-R:** Radial Leaded series. * **110:** Represents the 1.10 Amp hold current rating. * **-0:** Indicates that the leads are **straight** (un-kinked). * **-99:** Indicates the packaging type (typically **bulk packaging**). ### Dimensions (Approximate) * **Width:** ~13.0 mm * **Height:** ~18.0 mm * **Thickness:** ~3.0 mm * **Lead Spacing:** ~5.1 mm --- ## 4. Common Applications This component is typically used in circuits where overcurrent protection is needed but manual replacement of a fuse is difficult or undesirable: 1. **Industrial Controls:** Protecting PLCs and sensor loops. 2. **IEEE 1394 / USB Ports:** Protecting power rails from shorts. 3. **Security Systems:** Overload protection for sirens and sensors. 4. **Power Supplies:** Secondary side protection for transformers. ---