The **FSMD030-2016-R** is a specific model of a **Surface Mount Polymeric Positive Temperature Coefficient (PPTC)** device, commonly known as a Resettable Fuse. These components are used to protect electronic circuits from overcurrent conditions. --- ### 1. General Specifications The part number follows a specific nomenclature that defines its physical size and electrical behavior. | Parameter | Specification | | :--- | :--- | | **Component Type** | PPTC Resettable Fuse | | **Package Size (EIA)** | 2016 (Approx. 5.0mm x 4.0mm) | | **Hold Current ($I_{hold}$)** | 0.30 Amps (300mA) | | **Maximum Voltage ($V_{max}$)** | 60V DC | | **Maximum Current ($I_{max}$)** | 100 Amps | | **Mounting Type** | Surface Mount Device (SMD) | --- ### 2. How it Functions Unlike a traditional glass fuse that "blows" and must be replaced, the FSMD030-2016-R is "resettable": 1. **Normal State:** The device has a very low internal resistance, allowing current to flow freely to the load. 2. **Fault State:** If the current exceeds the "Trip Current" ($I_{trip}$), the internal polymer heats up rapidly. This causes a phase change that increases the resistance by several orders of magnitude, effectively "opening" the circuit. 3. **Reset State:** Once the power is removed and the fault is cleared, the device cools down and returns to a low-resistance state. --- ### 3. Electrical Characteristics Detail To design with this part, you must understand the relationship between current and temperature: * **Hold Current ($I_{hold}$):** The maximum current the device can carry without tripping at 23°C. * **Trip Current ($I_{trip}$):** The minimum current at which the device is guaranteed to trip (usually $2 \times I_{hold}$). * **Time to Trip:** This device is categorized as "Fast Trip," meaning it reacts quickly to protect sensitive semiconductors. * **Resistance ($R_{min}/R_{max}$):** The initial resistance typically ranges from **0.70 $\Omega$ to 2.50 $\Omega$**. --- ### 4. Common Applications Due to its 60V rating and 300mA hold current, this part is ideal for: * **IEEE 1394 (Firewire) Ports:** Protecting high-speed data lines. * **Industrial Controls:** Protecting sensors and PLC I/O ports. * **Automotive Electronics:** Protection for small motors or control modules. * **USB Port Protection:** Limiting current to prevent damage to the host controller. --- ### 5. Identification Marking The component is typically marked with a shorthand code. For the **FSMD030-2016-R**, you will usually see: `030` Printed on the top surface of the ceramic/polymer body.