## Overview of the MF-RX110-AP The **MF-RX110-AP** is a Radial Leaded Polymer Positive Temperature Coefficient (PPTC) resettable fuse manufactured by **Bourns**. It is part of the MF-RX series, designed to provide overcurrent protection for electronic circuits. --- ### Technical Specifications | Parameter | Specification | | :--- | :--- | | **Hold Current ($I_{hold}$)** | 1.10 Amperes | | **Trip Current ($I_{trip}$)** | 2.20 Amperes | | **Maximum Voltage ($V_{max}$)** | 60 Volts | | **Maximum Current ($I_{max}$)** | 40 Amperes | | **Power Dissipation ($P_d$ Typ.)** | 1.5 Watts | | **Resistance (Min/Max)** | 0.150 / 0.250 Ohms | | **Packaging Style** | Ammo Pack (indicated by "-AP") | --- ### Key Features and Functionality 1. **PPTC Technology**: Unlike standard fuses that "blow" and must be replaced, this device increases its resistance dramatically when an overcurrent or over-temperature condition occurs. Once the fault is removed and the power is cycled, the device cools down and "resets" to a low-resistance state. 2. **Ammo Pack Packaging**: The suffix **-AP** indicates that the parts are supplied in an Ammo Pack (folded tape), which is ideal for automated through-hole component insertion machinery. 3. **Radial Leaded Design**: The physical form factor consists of a disk with two leads extending from the same side, intended for through-hole mounting on PCBs. 4. **60V Rating**: This makes it suitable for higher voltage DC applications compared to standard 16V or 30V resettable fuses. --- ### Typical Applications * **Industrial Controls**: Protection against short circuits in PLC I/O ports. * **Security Systems**: Overcurrent protection for sensors and alarms. * **Power Supplies**: Used as a secondary protection layer for DC power outputs. * **Medical Equipment**: General circuit protection where reliability is critical. --- ### How it Works (Physics) When the current exceeds the **Trip Current**, the internal polymer matrix heats up and expands. This expansion breaks the conductive chains of carbon black within the polymer, causing the resistance to spike. This state is maintained as long as power is applied (it stays warm). Once the power is disconnected, the polymer shrinks, re-establishing the conductive paths.