LittelFuse announced setP Temperature Indicator that protects USB charging cables

Littelfuse, the global leader in circuit protection, introduced the polySwitch setP series Temperature Indicator that protects USB Type-C and USB-PD (USB-Power Delivery) charging cables from overheating. This announcement was made in the Littelfuse booth at Electronica India, the International Trade Fair for Electronic Components, Systems and Applications held from September 26 to September 28, 2018 at Bangalore International Exhibition Center in Bengaluru, India.

LittelFuse PolySwitch setP Temperature Indicator

When the connector of a USB Type-C cable is trapped with dust, dirt or other debris, a resistive fault is created between the power line and ground, which results in a temperature surge without increasing the current. The PolySwitch setP that is power independent detects the temperature rise and alerts the host device to shutdown the current flow at the charging port. Once the cable is removed from the charging port and the dust that causes the short-circuiting fault is dislocated, the charging operation will be resumed as soon as the charging cable is inserted to the charging port again. The setP device is provided in the compact 0805 footprint. The size of setP Temperature Indicator is 50% smaller than other competitive solutions that require placing a device on the power line. An extra device on the power line causes more power loss. Since the setP Temperature Indicator is power independent, the same device can be used to protect charging cables designed for 15W, 60W or 100W.

Typical applications for the setP Series Temperature Indicator include:

  • USB Type-C connectors for charging cables for mobile and wearable devices;
  • Power supply with attached USB Type-C cables;

Using setP Series Temperature Indicator offers many advantages include the following:

  • The compact size and sensitivity to temperature helps to simplify keeping the cable surface temperature safe for the users;
  • The rigid structure is compatible with conventional assembly and molding operations used in cable and connector manufacturing;
  • Being independent of USB power delivery allows for a smaller footprint and greater energy efficiency and simplifies part selection;

  • IHold = Hold current: maximum current device will pass without tripping in 20°C still air
  • ITRIP = Trip current: minimum current at which the deice will trip in 20°C still air
  • Max Volts = Maximum voltage device can withstand without damage at rated current (Imax)
  • Imax = Maximum fault current device can withstand without damage at rated voltage (Max Volts)
  • PD(Max) = Maximum power dissipated from device when in the tripped state at 20°C still air
  • RMIN = Minimum resistance if device in initial (un-soldered) state
  • R1max = Maximum resistance of device at 20°C measured on hour after tripping or reflow soldering of 260°C for 20 seconds (values specified were determined using PCBs with 0.115in x 1.0in ounce copper traces)


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