The **5MTP3.5-R** is a specific model of a subminiature, radial-leaded, time-delay (slow-blow) fuse manufactured by **Bel Fuse Inc.** This part is widely used in power supplies and consumer electronics to protect circuits from overcurrent conditions. --- ## 1. Technical Specifications The part number follows a specific nomenclature that defines its electrical characteristics: | Property | Specification | | :--- | :--- | | **Current Rating** | 3.5 Amperes | | **Voltage Rating (AC)** | 250V AC | | **Fuse Type** | Time-Lag / Slow-Blow (T) | | **Form Factor** | Radial Lead (Micro-fuse) | | **Body Material** | Thermoplastic (usually blue or black) | | **Interrupting Rating** | 100A @ 250V AC | | **RoHS Compliant** | Yes (indicated by the "-R" suffix) | --- ## 2. Key Features The 5MTP series is designed with several critical physical and functional attributes: * **Time-Delay Characteristic:** Unlike fast-acting fuses, the "Slow-Blow" nature allows the fuse to withstand temporary surges (like inrush current from a motor or capacitor) without blowing, while still protecting against sustained overloads. * **Space-Saving Design:** Its radial lead configuration allows it to be mounted vertically on a PCB, saving significant "real estate" compared to traditional glass tube fuses. * **Solderability:** The leads are typically tin-plated, making them ideal for wave soldering or manual PCB assembly. * **Safety Standards:** These parts are generally UL, CSA, and VDE recognized, ensuring they meet global safety requirements for electronic equipment. --- ## 3. Typical Applications The 5MTP3.5-R is commonly found in the following environments: 1. **Switching Power Supplies:** To handle the initial surge when the device is plugged in. 2. **Battery Chargers:** Protecting the charging circuit from short circuits. 3. **Monitors and Televisions:** Used in the primary side of the power board. 4. **Industrial Controllers:** Protecting sensitive I/O ports. --- ## 4. Part Number Breakdown Understanding the Bel Fuse naming convention: | Segment | Meaning | | :--- | :--- | | **5MTP** | Series designation (5mm Radial, Time-Lag) | | **3.5** | Amperage (3.5A) | | **-R** | RoHS (Lead-Free) compliant |