Overheat protection PTC thermistors in USB cable

Fri Jul 22 10:05:21 CST 2022

Overheat protection PTC thermistors in USB cable

Our HornmicLink cable will add an overheat auto-protection function into the USB cable sometimes according to the requirements. The cable will automatically reduce the current to lower the temperature if the current is too high and the temperature rises to too high when the cable is in use, thus protecting the customer's equipment from damage. The key to this function is the PTC thermistor, and it is described in detail below.

Type-C plug with PTC S45

Type-C plug with PTC S45 design drawing

What’s PTC?

PTC is the abbreviation of Positive Temperature Coefficient, which means positive temperature coefficient and refers to the semiconductor material or component with positive temperature coefficient. Usually we refer to a PTC as a thermistor with positive temperature coefficient, and its resistance value will rise rapidly in steps with the increase of temperature above a certain temperature (Curie temperature , Tc).

PTC Resistance-Temperature Curve

PTC Resistance-Temperature Curve

The opposite of PTC is Negative Temperature Coefficient, also known as NTC, which is the opposite of PTC, i.e., when the temperature exceeds a certain level, its resistance value decreases rapidly in steps with the increase of temperature.

S45 PTC Temperature-Time Curve

PTC Temperature-Time Curve

USB3.0 ports can operate at up to 3000mA, which can easily overheat charging devices and therefore require Over-Current Protection.

Type-C Cable With PTC Thermistor

The thermistor must meet two criteria.

(1) be able to break the circuit 6000 times and still have the PTC protection capability.

(2) Maintain the disconnected state for 1000 hours and still have the PTC protection capability.



We HornmicLink USB Cable are committed to the quality of our products and the safety of our customers, and welcome negotiations and bulk purchases.



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By HornmicLink_Henry