Last year, the USB Implementers Forum, Inc. (USB-IF) announced USB Power Delivery Specification Revision 3.1 (USB PD3.1 specification), which supported higher power range, up to 48 Volts, 5 Amps and 240 Watts. This means that a comprehensive upgrade will be carried out on power adapters, USB Type-C cables and electronic devices. For the USB Type-C cables, the requirements for safety performance will be higher.
Safety of USB Type-C Cables
The USB PD3.1 specification still adopts the USB Type-C port, which has a pin pitch of 0.5 mm, which is much more compact than the 2.5 mm in a USB Type-A port. In this case, USB Type-C ports are more vulnerable by contaminants such as dust and liquid. When contaminants enter the USB Type-C port, it may form a micro-short circuit between VBUS pin and GND pin at the USB Type-C port. This can cause the interface to overheat and cause a fire.
Figure 1. The burned USB Type-C ports
In addition, frequent plugging and unplugging may cause mechanical failure of the USB Type-C port. These failures can destroy the computer’s interface and cause serious damage to electronic devices, possibly even injuring the user through electric shock or causing a fire.
In order to solve the above issues, an over-temperature protection solution for the interface is required.
Figure 2. The USB Type-C cable spontaneously combusts
Over Temperature Protection for the USB Type-C Cables with USB eMarker HUSB332C
The new generation USB eMarker HUSB332C from Hynetek Semiconductor Co., Ltd. (www.hynetek.com) is compatible with USB PD3.1 specification, and supports up to 240 Watts charging power, while integrating Over Temperature Protection (OTP) with Hynetek patented OTP function to ensure superior performance and effective protection for the USB Type-C cables. The HUSB332C comes with temperature detection with pre-set protection temperature limit values. When the USB Type-C port overheats, the HUSB332C will detect the temperature inside the USB Type-C port and once the temperature exceeds the OTP limit value, it will send a reset signal to the USB PD power supply to cut off the VBUS power to protect the circuit. When the temperature drops below the OTP limit, the power delivery recovers.
Figure 3. Waveform diagram of HUSB332C during over-temperature test
Figure 4. Reference circuit of “One Cable with Two eMarkers”
The reference circuit of “One Cable with Two eMarker” using the HUSB332C can meet the cable’s over-temperature protection requirements. [Note: ” One Cable with Two eMarkers ” means there is one eMarker at each end of the USB Type-C cable.]
Solution Analysis of ” One Cable with Two eMarkers”
Figure 5. Examples of “One Cable with Two eMarker”
With the introduction of USB PD3.1 specification, USB4 Gen3 specification, Thunderbolt 4 specification and other specifications, as shown above, the ” One Cable with Two eMarkers ” cables which supports for high-power current transfer, ultra-high-speed data transfer, video signal transfer, are frequently seen in the market. Among them, the original assembly cable in Samsung’s new Galaxy S22 series 45W travel charger adopts the “One Cable with Two eMarkers” design. There is one HUSB332A (the USB eMarker from Hynetek) at both ends of the cable.
The HUSB332A’s high performance and reliability has been proven by many well-known companies and the USB Type-C cable market. On the upgrade of the HUSB332A, the HUSB332B can support USB PD3.1 specification. In addition, the HUSB332C enhances the over temperature protection (OTP) function.
Comparison of four OTP Solutions for the USB Type-C Cables
Comparing the four over-temperature protection solutions for the USB cables in the market, we can easily find that the over-temperature protection solution by using USB eMarker has the obvious advantages of small size and high cost performance. The USB eMarker chip is required by the USB-IF to meet the charging requirements of 3 Amps and above. So when USB eMarker integrates the OTP function, the cable can be protected without the need for additional OTP circuit. This greatly reduces the number of peripheral devices, while also reducing cost.
Key Product Features of the USB eMarker HUSB332C
If you are looking for an Over-Temperature Protection Solution for USB Cables, please visit https://en.hynetek.com or contact sales@hynetek.com for details.
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