Offering an effective overtemperature protection solution, Bourns^® TCO devices, also known as mini-breakers, have ingeniously enhanced existing technology in such a way to develop their protection capabilities.
TCO devices have been proven to protect batteries, cables and ICs from damage from overheating by acting independently of any controller.
Constructed with a bimetal disk and a ceramic PTC in parallel, the Bourns^® TCO family delivers the best features of both. The bimetal disk reacts in a precise manner to changes in the ambient temperature.
Once triggered, it limits the current and diverts the current into the PTC.
The PTC generates heat to keep the bimetal open and provides a self-holding function.

Bourns^® Model SD Series Mini-breakers
INTRODUCTION
With the introduction of the new Model SD Series Thermal Cutoff devices (TCOs), Bourns is pushing the boundaries of overtemperature protection compared to traditional devices that have come before it.
The SD series deliver several industry FIRSTs:

• ・First TCO series that can be either surface mounted or welded.
• ・First TCO series with trip temperature ranges from 55 ˚C up to 150 ˚C(Previous models only supported from 72 ˚C up to 85 ˚C or 90 ˚C)
• ・First TCO series offering non-automatically resettable (self-hold function) or automatically resettable (non self-hold) function options
• ・First TCO series tested to pass AEC-Q200 equivalent test standards

The advanced technology and features in these versatile series significantly broaden their use in a new and wider range of markets and applications.