Bourns Thermal Cutoff Devices

Video Highlights Safety Issues with USB Type-C Cables

If you are using the latest USB Type-C cables that offer super-speed 10 gigabit-per-second performance, there are safety threats you need to be aware of.  In addition to the increased power capability and bandwidth achieved in this latest USB standard, the connector has been changed. It is upgraded from the original simple 4-pin D+/ D- Power and GND format and now combines multiple connector functions into one. Cramming all this functionality into a single connector also needed to meet size constraints, so the design of the new USB Type-C connector features 24 pins in a smaller form factor.

It is fairly easy to deduce that due to the much higher power delivery coupled with the extremely tight pin spacing in Type-C cables, there is an increased risk of overheating and fire. Accidents, misuse and exposure to liquids and foreign materials can cause pin and shell damage that can lead to excessive heat generation at the connector.

Bourns has documented these safety risks in a new video


In it, you will see the thermal event tests we have performed and the damage that can be caused after just 15 minutes. These potential safety issues are too important to ignore.

A solution is to integrate overcurrent and overtemperature protection into USB Type-C cables and connectors.  Designed to be easily integrated, Bourns® Thermal Cutoff or TCO devices, are also known as mini-breakers. The key to providing reliable, effective overtemperature protection is in how Bourns has constructed its TCO devices by using a bimetal disc and ceramic PTC in parallel. If the USB connector overheats, it causes the bimetal to open at a very accurate temperature.  Once open, the current passes through the PTC generating sufficient heat to keep the bimetal open and prevents nuisance resetting.

An optimal TCO overtemperature solution is our Model SC Series that offers high current capacity up to 13 A at 25 °C.  Available with surface mount packaging, the SC Series provides significant benefits enabling manufacturers to board-mount them onto battery charge circuit boards, which can help to reduce assembly costs and supply chain lead times. It is also 38% smaller than Bourns’ previous generation TCO devices yet has the same high current handling capacity so it can be used in a wider range of battery-based applications where space and connector density require reliable, efficient overtemperature protection.

Yes, there is a way to enjoy the faster performance and power delivered from USB Type-C technology while being free from overheating and fire concerns.


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