## Overview of the Bourns MF-R1100 The **MF-R1100** is a high-current, radial-leaded **PTC (Positive Temperature Coefficient) Resettable Fuse**, part of the Multifuse® family manufactured by Bourns. Unlike traditional fuses that blow and must be replaced, this device increases its resistance significantly during an overcurrent event and resets once the fault is cleared and the power is cycled. --- ### Technical Specifications The table below summarizes the key electrical characteristics of the MF-R1100: | Parameter | Symbol | Value | | :--- | :--- | :--- | | **Hold Current** | $I_{hold}$ | 11.0 Amperes | | **Trip Current** | $I_{trip}$ | 22.0 Amperes | | **Maximum Voltage** | $V_{max}$ | 16 Volts (DC/AC) | | **Maximum Current** | $I_{max}$ | 100 Amperes | | **Power Dissipation** | $P_d$ | 4.5 Watts (Typical) | | **Resistance (Initial)** | $R_{min} / R_{max}$ | 0.003 to 0.010 Ohms | | **Operating Temp** | $T_{op}$ | -40°C to +85°C | --- ### Operating Principle The device functions based on the properties of a conductive polymer composite: 1. **Normal State:** At standard operating currents, the conductive particles inside the polymer form low-resistance chains, allowing current to flow easily. 2. **Tripped State:** When an overcurrent occurs, $I^2R$ heating causes the polymer to expand. This breaks the conductive chains, causing the resistance to spike almost instantly. This "trips" the fuse, limiting the current to a safe leakage level. 3. **Reset State:** Once the power is disconnected and the device cools down, the polymer contracts, the conductive paths re-form, and the device returns to a low-resistance state. --- ### Physical Characteristics and Material * **Package Type:** Radial Leaded (Through-hole). * **Encapsulation:** Cured, flame-retardant epoxy polymer (meets UL 94V-0 requirements). * **Lead Material:** Tin-plated copper. * **Marking:** Part identification, hold current (1100), and date code are typically printed on the body. --- ### Typical Applications Due to its high hold current (11A) and low voltage rating (16V), the MF-R1100 is commonly found in: * **Automotive Electronics:** Protection for motors and heavy-duty sensors. * **Rechargeable Battery Packs:** Preventing damage from short circuits during high-discharge cycles. * **Power Supplies:** Low-voltage, high-current power rails. * **Industrial Controls:** Protecting actuators and large relays. --- ### Safety Agency Approvals The MF-R1100 is designed to meet strict safety standards: * **UL Recognized:** File Number E174545. * **CSA Accepted:** File Number CA110338. * **TÜV Certified:** Certificate Number R 02057213.