Thermal Sensitive SMD USN 1206 Fuses Schurter Thermal Sensitive SMD USN 1206 Fuses have a built-in customer-specific time-current tripping feature. The temperature-sensitive SMD fuses are impermeable to potting compound and exhibit high melting I²t values. The Schurter fuses protect against both overcurrent and excessive ambient temperature, making them ideal in all electronics with temperature-critical components. These fuses feature an admissible ambient air temperature rating of -40°C to 125°C and have a flammability rating of UL 94V-1.