SCHURTER’s RTS thermal fuse for SMD mounting, successfully launched in 2018, is now available with an integrated shunt. The RTS is a particularly compact overtemperature protection device for power semiconductors used in high density, high-performance circuit boards to protect against thermal runaway.

Thermal runaway refers to the overheating of a power semiconductor due to a self-reinforcing, heat- producing process omnipresent in the trend toward circuit miniaturization. The RTS protects these power semiconductors against thermal runaway. In such an event, the thermal fuse reliably interrupts the circuit at a precisely defined temperature as a fail-safe device.

The RTS and RTS with shunt sustain operating currents up to 130 A at rated voltages of up to 60 VDC in a remarkable compact package measuring 6.6 x 8.8 mm in size.  The shunt version has an integrated resistance with a very low temperature dependence. This resistance, known as a shunt, enables precise current measurement and enables an additional – non-thermal – circuit protection, e.g. via a controller.

The RTS can be mounted using conventional reflow soldering techniques with temperature profiles up to 260 °C. After the solder process, the RTS is mechanically activated by depressing the top into place, arming the RTS to trip at 210 °C. It can be performed manually or automatically in the case of several devices being activated at once. In contrast to devices using electrical activation, with an additional contact, the status of the RTS is clearly and immediately visible to the installer. The need for an additional contact is also eliminated.