The **MF-PSHT-LAB** is a specific part number within the Bourns MF-PSHT series of resettable fuses. These components are Surface Mount Devices (SMD) based on Polymer Positive Temperature Coefficient (**PPTC**) technology. --- ### 1. General Specifications The MF-PSHT series is specifically designed for high-temperature environments, often used in automotive or industrial applications where standard fuses might trip prematurely due to ambient heat. | Feature | Specification (MF-PSHT Series) | | :--- | :--- | | **Component Type** | PPTC Resettable Fuse | | **Package Size** | 0805 (Metric 2012) | | **Technology** | FreeXpansion™ (Lead-free, RoHS compliant) | | **Operating Temp Range** | -40 °C to +125 °C | | **Hold Current ($I_{hold}$)** | Typically 0.05A to 0.50A (depending on suffix) | | **Voltage ($V_{max}$)** | 9V to 30V | --- ### 2. How it Works (PPTC Principle) Unlike a traditional thermal fuse that blows and must be replaced, the MF-PSHT functions as follows: 1. **Normal State:** The conductive polymer has low resistance, allowing current to flow. 2. **Fault State:** During an overcurrent or over-temperature event, the polymer heats up and expands. 3. **Tripped State:** The expansion causes the conductive particles to separate, increasing resistance dramatically and "opening" the circuit. 4. **Reset:** Once power is removed and the device cools, the polymer contracts, restoring the conductive path. --- ### 3. Key Applications Because of its high-temperature rating (up to 125 °C), it is commonly found in: * **Automotive Electronics:** Sensors, Infotainment, and ECU protection. * **Industrial Controls:** High-density boards subject to internal heat buildup. * **USB Port Protection:** Protecting against shorts in portable devices. --- ### 4. Technical Characteristics | Parameter | Description | | :--- | :--- | | **$I_{hold}$** | The maximum current the device can carry without tripping. | | **$I_{trip}$** | The minimum current that will cause the device to trip. | | **$R_{min} / R_{1max}$** | The resistance range of the device before and 1 hour after tripping. | | **AEC-Q200** | Most MF-PSHT parts are AEC-Q200 compliant for automotive reliability. | --- ### 5. Part Number Suffixes The "-LAB" suffix in your specific query usually refers to a **Design Kit** or a specific **Laboratory sample pack** containing various values of the MF-PSHT series for prototyping purposes, rather than a single production reel of one specific value.