The **6125FF3.5-R** is a high-performance Surface Mount Device (SMD) fuse designed for overcurrent protection in various electronic circuits. It is manufactured by **Eaton (formerly Bussmann)**. --- ## 1. Technical Specifications The part number follows a specific nomenclature that defines its physical and electrical characteristics. | Parameter | Specification | | :--- | :--- | | **Manufacturer** | Eaton (Bussmann Series) | | **Series** | 6125FF (Fast-Acting) | | **Current Rating** | 3.5 Amperes | | **Voltage Rating (AC)** | 125 VAC | | **Voltage Rating (DC)** | 72 VDC | | **Package Size** | 6125 (Metric) / 2410 (Imperial) | | **Interrupt Rating** | 50A at 125VAC / 300A at 72VDC | | **Operating Temp** | -55°C to +125°C | | **RoHS Compliant** | Yes (indicated by the "-R" suffix) | --- ## 2. Key Features The 6125FF3.5-R is distinguished by several engineering traits: * **Fast-Acting (FF):** The "FF" stands for Very Fast-Acting. This means the fuse is designed to open almost instantly when an overcurrent condition occurs, protecting sensitive downstream components (like ICs and semiconductors). * **Brick/Block Design:** Unlike thin-film fuses, the 6125 series uses a wire-in-air or ceramic body construction, which provides better thermal stability and higher interrupt ratings. * **Solderability:** It features gold-plated end caps, providing excellent solderability and resistance to corrosion/oxidation. --- ## 3. Physical Dimensions The "6125" designation refers to the physical footprint in millimeters. * **Length:** 6.1 mm (± 0.2mm) * **Width:** 2.5 mm (± 0.1mm) * **Height:** 2.5 mm (± 0.1mm) --- ## 4. Typical Applications This fuse is commonly found in industrial and consumer electronics where space is limited but high reliability is required: 1. **LCD Monitors & Televisions:** Protecting backlight inverters and main logic boards. 2. **Power Supplies:** Used in DC-DC converters and AC-DC adapters. 3. **Medical Equipment:** High-reliability circuit protection for diagnostic tools. 4. **Telecom:** Base station power modules and line cards. --- ## 5. Part Number Breakdown ```text 6125 FF 3.5 - R | | | | | | | +-- RoHS Compliant | | +--------- Current Rating (3.5 Amps) | +-------------- Fast-Acting Characteristic +------------------- Package Size (6.1mm x 2.5mm) ```