The **MF-RX014/250-A** is a specialized electronic component known as a **Resettable Fuse** (or PPTC - Polymeric Positive Temperature Coefficient device). It is manufactured by Bourns and is specifically designed for high-voltage telecommunications and networking applications. --- ### 1. Key Technical Specifications The following table outlines the critical electrical parameters for this device: | Parameter | Specification | Description | | :--- | :--- | :--- | | **Hold Current ($I_{hold}$)** | 0.14 A | The maximum current the device can carry without tripping. | | **Trip Current ($I_{trip}$)** | 0.28 A | The current at which the device will switch to a high-resistance state. | | **Max Voltage ($V_{max}$)** | 60V / 250V | 60V continuous; can withstand 250V surges (interrupt). | | **Max Current ($I_{max}$)** | 3.0 A | The maximum fault current the device can safely withstand. | | **Resistance ($R_{min}/R_{max}$)** | 6.0 $\Omega$ / 12.0 $\Omega$ | The initial resistance range of the device at 23°C. | | **Packaging** | Radial Lead | Through-hole mounting style. | --- ### 2. Physical and Chemical Composition The "MF-RX" series utilizes a unique conductive polymer blend: - **Carbon Black Particles:** These are embedded in a non-conductive crystalline polymer. - **The "Switch" Mechanism:** Under normal conditions, the carbon particles form conductive chains (low resistance). When an overcurrent occurs, the polymer heats up and expands, breaking the carbon chains and causing the resistance to spike (high resistance). - **Resetting:** Once the fault is cleared and the device cools down, the polymer shrinks, the chains reconnect, and the fuse "resets" to a low-resistance state. --- ### 3. Part Number Breakdown: `MF-RX014/250-A` Understanding the nomenclature helps identify the specific protection level: * **MF:** Multifuse® (Bourns Trademark). * **RX:** Radial Leaded series (Standard through-hole). * **014:** Hold Current rating (0.14 Amps). * **250:** Voltage Rating (250V Max Interrupt). * **A:** Specific designator, often referring to compliance with certain standards or specific physical dimensions/packaging. --- ### 4. Common Applications Due to its high voltage rating (250V), this part is typically used in environments where AC power crossing or lightning strikes are a risk: * **Customer Premise Equipment (CPE):** Modems, routers, and set-top boxes. * **Telecommunications:** Protection for tip/ring circuits in analog phone lines. * **Industrial Controls:** Protecting low-power sensors from accidental wiring to mains power.