The **MF-RHT070** is a high-temperature, radial-leaded **Polymeric Positive Temperature Coefficient (PPTC)** resettable fuse, manufactured by Bourns. These components are commonly used for overcurrent protection in environments where operating temperatures are elevated. --- ### 1. Technical Specifications The table below summarizes the key electrical characteristics of the MF-RHT070: | Parameter | Specification | Description | | :--- | :--- | :--- | | **$I_{hold}$** | 0.70 Amps | Maximum current the device will hold without tripping at 23°C. | | **$I_{trip}$** | 1.30 Amps | Minimum current at which the device will always trip at 23°C. | | **$V_{max}$** | 16 Volts | Maximum voltage the device can withstand without damage. | | **$I_{max}$** | 100 Amps | Maximum fault current the device can safely interrupt. | | **$P_{d}$** | 0.85 Watts | Power dissipated from the device when in tripped state. | | **Operating Temp** | -40°C to +125°C | Wide range suitable for automotive and industrial use. | --- ### 2. How it Functions The MF-RHT070 operates on the principle of thermal expansion: 1. **Normal State:** The conductive particles within the polymer form a low-resistance path, allowing current to flow to the load. 2. **Fault Condition:** If an overcurrent or overtemperature event occurs, the polymer heats up and expands. 3. **Tripped State:** The expansion breaks the conductive chains, causing the resistance to increase exponentially (limiting the current). 4. **Resetting:** Once the fault is removed and the device cools down, the polymer contracts, the conductive paths re-establish, and the fuse "resets." --- ### 3. Key Features & Applications #### Features * **High Temperature Rating:** Unlike standard PTCs (85°C), the RHT series is rated for **125°C**, making it ideal for "under-the-hood" automotive applications. * **Resettable:** Eliminates the need for physical fuse replacement after a surge. * **Radial Leaded:** Easy to mount on Through-Hole PCBs. #### Typical Applications * **Automotive Electronics:** Protection for motors, actuators, and ECU power lines. * **Industrial Controls:** Overcurrent protection in harsh manufacturing environments. * **Telecommunications:** Protection against power cross and induction. --- ### 4. Resistance Values | Resistance Type | Value | Condition | | :--- | :--- | :--- | | **$R_{min}$** | 0.300 $\Omega$ | Minimum initial resistance before tripping. | | **$R_{1max}$** | 0.700 $\Omega$ | Max resistance 1 hour after tripping/reflow. |