The **MST-1-R** refers to a specific series of **Micro Fuses** manufactured by **Bel Fuse Inc.** These components are widely used in consumer electronics, power supplies, and industrial equipment for overcurrent protection. Below is a detailed breakdown of its electronic characteristics and specifications. --- ### 1. General Overview The MST-1-R is a **Radial Lead Micro Fuse**. Unlike traditional glass tube fuses, these are small, rectangular or cylindrical plastic-housed components that are soldered directly onto a Printed Circuit Board (PCB). | Feature | Specification | | :--- | :--- | | **Type** | Subminiature Radial Lead Fuse | | **Speed** | Time-Lag (Slow Blow) / Type T | | **Standard** | IEC 60127-3, Sheet 4 | | **RoHS Status** | RoHS 2 Compliant (Lead-Free) | --- ### 2. Key Technical Specifications The "1" in the part number typically denotes the amperage, and the "R" indicates RoHS compliance. | Parameter | Value/Range | | :--- | :--- | | **Current Rating** | 1 Ampere (for MST 1) | | **Voltage Rating** | 250V AC | | **Interrupting Rating** | 35A or 10x rated current (whichever is greater) | | **Housing Material** | Thermoplastic (UL 94-V0) | | **Lead Material** | Tin-plated Copper | | **Operating Temp** | -55°C to +125°C | --- ### 3. Electrical Characteristics (Time-Current) Because it is a **Time-Lag** fuse, it is designed to ignore short-duration "inrush currents" (like when a motor starts or a capacitor charges) but will blow if a sustained overload occurs. | Overload % | Blow Time (Limits) | | :--- | :--- | | **150%** | No Trip (1 Hour minimum) | | **210%** | Max 2 Minutes | | **275%** | 400ms to 10 Seconds | | **400%** | 150ms to 3 Seconds | | **1000%** | 20ms to 150ms | --- ### 4. Physical Dimensions & Layout The MST series uses a standardized radial form factor, making it ideal for high-density PCB layouts. * **Body Diameter:** ~8.35 mm * **Body Height:** ~7.7 mm * **Lead Spacing:** 5.08 mm (Standard pitch) * **Lead Length:** Usually 4.3 mm (short) or 18.8 mm (long/pigtail) --- ### 5. Common Applications * **Power Supplies:** Protection for AC/DC adapters. * **Consumer Electronics:** Televisions, chargers, and LED drivers. * **Industrial:** Protection for PLCs and small motors. * **Battery Chargers:** To prevent thermal runaway during circuit failure.