The **3SBP7-R** is a specific model of a subminiature, slow-blow (time-delay) fuse manufactured by **Bel Fuse Inc.** This part is widely used in power supplies, chargers, and industrial consumer electronics where space is limited but circuit protection is critical. --- ## 1. Technical Specifications The part number itself contains encoded information about its electrical characteristics. | Parameter | Specification | | :--- | :--- | | **Fuse Type** | Glass Body / Subminiature | | **Current Rating** | 7 Amperes (indicated by the '7') | | **Voltage Rating** | 250V AC | | **Characteristic** | Slow-Blow / Time-Delay (SB) | | **Dimensions** | 3.6mm x 10mm | | **Mounting Type** | Axial Leaded (Through-hole) | | **RoHS Compliant** | Yes (indicated by the '-R' suffix) | --- ## 2. Component Breakdown Understanding the nomenclature helps in identifying the part's physical and functional properties: ### A. The "3SBP" Series * **3SB**: Refers to the physical size (3.6mm diameter) and the "Slow-Blow" characteristic. Slow-blow fuses are designed to withstand temporary current surges (like motor startups) without blowing immediately. * **P**: Indicates "Pigtail" or Axial Leads. These are wire leads coming out of both ends of the glass tube, allowing the fuse to be soldered directly onto a Printed Circuit Board (PCB). ### B. The "7" * This represents the **Ampere Rating**. This specific fuse will carry 7 Amps continuously. It will trigger a disconnect if the current exceeds this limit for a duration defined by its time-delay curve. ### C. The "-R" * This suffix stands for **RoHS (Restriction of Hazardous Substances)** compliance. It ensures the part is lead-free and meets international environmental standards. --- ## 3. Common Applications Due to its small form factor and time-delay nature, the 3SBP7-R is found in: * **LED Lighting Drivers:** Protecting against inrush current. * **AC Adapters:** Small power bricks for laptops or monitors. * **Power Supplies:** Serving as the primary input protection on the AC line. * **Battery Chargers:** Preventing over-current damage during the charging cycle. --- ## 4. Key Performance Data * **Interrupting Rating:** Usually rated for 35A at 250V AC or 10,000A at 125V AC (standard for this series). * **Safety Agency Approvals:** Typically UL listed and CSA certified.