The **5TTP 750-R** is a specific type of electronic protection component, primarily categorized as a **Time-Delay (Slow-Blow) Glass Tube Fuse**. It is part of the "5TTP" series manufactured by Bel Fuse Inc. Below is a detailed breakdown of its specifications, construction, and applications. --- ### 1. Key Technical Specifications The model number "750-R" specifically indicates its current rating and RoHS compliance. | Property | Specification | | :--- | :--- | | **Current Rating** | 750 mA (0.75 Amps) | | **Voltage Rating** | 250V AC | | **Fuse Type** | Time-Delay / Slow-Blow (T-type) | | **Dimensions** | 5mm x 20mm (Standard Miniature Size) | | **Body Material** | Glass | | **Termination Style** | Pigtail Leads (Axial Leaded) | | **Resistance** | Approximately 0.22 Ohms (Typical) | | **RoHS Compliant** | Yes (indicated by the "-R" suffix) | --- ### 2. Physical Components & Construction The 5TTP 750-R is not a standard "clip-in" fuse; it is designed for permanent installation on a PCB (Printed Circuit Board). 1. **Glass Tube:** The transparent body allows for visual inspection to see if the internal element has melted/blown. 2. **Internal Element:** A coiled wire or a weighted filament designed to withstand short-duration surges (like motor startups) without breaking. 3. **End Caps:** Nickel-plated brass caps that secure the glass and provide the electrical connection. 4. **Pigtail Leads:** Tin-plated copper wires soldered to the end caps. These allow the fuse to be soldered directly into through-holes on a circuit board, eliminating the need for a fuse holder. --- ### 3. Electrical Behavior: Time-Delay vs. Fast-Acting The "Time-Delay" characteristic is crucial for certain electronics. Unlike "Fast-Acting" fuses that blow instantly when the limit is reached, the 5TTP 750-R can handle: * **Inrush Currents:** High current spikes that happen the moment a device is turned on. * **Inductive Loads:** Useful for circuits with small motors or transformers that have temporary power surges. * **Sustained Overload:** It will only blow if the 750mA limit is exceeded for a specific duration (usually several seconds at 200% load). --- ### 4. Common Applications * **Power Supplies:** Protecting the input stage of AC/DC adapters. * **Industrial Controls:** Small motor circuits where start-up current is higher than operating current. * **Consumer Electronics:** LED drivers, chargers, and audio equipment where space is limited and a permanent fuse is preferred.