The **MJS125-R** is a specific model of a **Miniature Surface Mount (SMD) Fuse**, typically manufactured by Bel Fuse Inc. It is part of the MJS series, designed for space-constrained circuit protection. --- ## 1. Technical Specifications The following table highlights the primary electronic characteristics of the MJS125-R: | Parameter | Specification | |:---|:---| | **Rated Current** | 125 mA (0.125A) | | **Rated Voltage** | 125V AC / 125V DC | | **Fuse Type** | Slow Blow / Time Delay | | **Package / Case** | 2-SMD, Square End Block | | **Breaking Capacity** | 50A @ 125V AC/DC | | **Operating Temperature** | -55°C to +125°C | | **RoHS Status** | RoHS Compliant (Lead-Free) | --- ## 2. Key Features and Behavior ### A. Time-Delay (Slow Blow) Characteristic The "Slow Blow" nature of the MJS125-R allows it to withstand temporary **inrush currents** or surges without blowing. This is essential for circuits containing capacitors or small motors that draw high current for a fraction of a second upon startup. ### B. "R" Suffix Meaning In the Bel Fuse nomenclature, the **-R** suffix typically denotes: 1. **RoHS Compliance:** The part is manufactured using lead-free materials and processes. 2. **Tape and Reel Packaging:** Often indicates the part is supplied on a reel for automated SMT (Surface Mount Technology) assembly lines. --- ## 3. Typical Applications Because of its small footprint and low current rating, it is commonly used in: * **Telecommunications:** Protection for line cards and networking equipment. * **Power Supplies:** Secondary side protection for small AC/DC converters. * **Industrial Electronics:** Protecting sensitive control sensors. * **Consumer Electronics:** Battery chargers and portable handheld devices. --- ## 4. Visual Identification & Physical Properties * **Mounting:** SMD (Surface Mount Device). * **Dimensions:** Approximately 6.10mm x 2.69mm (Standard square-body SMD fuse size). * **Marking:** Usually marked with a code (like "T 125mA") to identify its slow-blow nature and current rating.