The **MF-RX110** is a specific model of **PTC (Positive Temperature Coefficient) Resettable Fuse**, manufactured by Bourns. It is part of the Multifuse® polymer-based product line, designed to protect circuits from overcurrent and short-circuit conditions. --- ### 1. Key Technical Specifications The following table summarizes the primary electrical characteristics of the MF-RX110: | Parameter | Specification | Description | | :--- | :--- | :--- | | **Hold Current ($I_{hold}$)** | 1.10 A | The maximum current the device can carry without tripping. | | **Trip Current ($I_{trip}$)** | 2.20 A | The minimum current at which the device will switch to high resistance. | | **Max Voltage ($V_{max}$)** | 60 V | Maximum voltage the device can withstand without damage. | | **Max Current ($I_{max}$)** | 40 A | Maximum fault current the device can safely handle. | | **Power Dissipation ($P_d$)** | 1.50 W | Power dissipated when the device is in its tripped state. | | **Operating Temp Range** | -40°C to +85°C | The environmental temperature limits for operation. | --- ### 2. How it Functions The MF-RX110 operates as a **thermistor**. Unlike a traditional fuse that "blows" and must be replaced, the MF-RX110 resets itself once the fault is cleared and the temperature drops. 1. **Normal State:** The polymer material contains conductive carbon black particles, creating a low-resistance path for current. 2. **Fault Condition:** Excess current causes $I^2R$ heating. The polymer expands, breaking the conductive chains. 3. **Tripped State:** Resistance increases exponentially, limiting the current to a safe leakage level. 4. **Reset:** Once the power is disconnected or the fault is removed, the device cools down, the polymer contracts, and the conductive path is restored. --- ### 3. Physical Attributes & Package * **Package Type:** Through-hole radial leaded. * **Material:** Cured, flame-retardant epoxy polymer (meeting UL 94V-0 requirements). * **Visual ID:** Usually yellow or orange with markings indicating the series (RX) and the hold current (110). --- ### 4. Common Applications The MF-RX110 is typically used in environments where reliability and "fit-and-forget" protection are required: * **Industrial Controls:** Protecting sensors and PLC I/O ports. * **IEEE 1394 / USB Ports:** Protecting against peripheral shorts. * **Security Systems:** Overcurrent protection for alarms and sensors. * **Power Supplies:** Secondary side protection for transformers.