Universal Serial Bus (USB) Type-C connectors specify and simplify connections between popular consumer devices. The use of USB-C for high-speed, safety-independent features such as infotainment also benefits car system designers. However, traditional USB-C connectors customized for consumer applications do not provide the robustness, reliability, and safety required in the automotive environment.
This paper briefly describes the USB-C and the challenges faced by designers in integrating USB-C into vehicle design, and then the HiUSB-C connectors that designers can use to overcome these challenges.
The Evolution of USB
From the original basic type-A form USB, USB connectors have replaced many traditional buses, such as parallel ports and RS-232, in consumer, test instrument and even industrial applications. This benefits from ease of use, low cost, small size, fast and easy plugging and unplugging, power and digital signal processing capabilities, and extensive vendor support from Plug and Play. The enhanced USB-C version allows smaller physical dimensions, faster speeds, greater power handling, and positive and negative plugging.
The great success of the USB-C connector has made it the unified standard that must be implemented by all new smartphones and small consumer devices, resulting in extremely high sales and stronger device interoperability.g. The standard USB-C is 8.4 mm x 2.6 mm in size and provides 24 pins. Symmetrical design (positive and negative blind plug) is adopted for the connector body and pin, and anti-freeze key is not required. This connector can also be used for simultaneous data transfer and charging, with extended functionality to support DisplayPort Alt mode and HDMI adaptors and bridges for audio and video data transfer.
These features are of great benefit to designers of automotive entertainment systems. In this respect, USB-C has the potential to reduce cost, convenience, and weight compared to other ways of connecting, while also building an extensive existing USB resource ecosystem.
Although USB-C has broad prospects in automotive applications, designers must address a number of challenges, including severe vibration and temperature fluctuations, high electromagnetic interference (EMI), and potential hazardous failures caused by unmatched USB cables and connectors.g.
Bringing USB-C into the automotive world
To meet the need for a suitable connector, Hioffers AU1 series USB-C connectors that meet the unique requirements of the automotive environment. This series of connectors bridge the interconnection between internal and external equipment and support standards such as USB 3.2 Gen2, DisplayPort 1.4 and HDMI. This family of devices is built on the existing HiCX series and operates seamlessly with it (Figure 1).
HIROSE AUTOMOBILE GRADE USB-C CONNECTOR
Figure 1: AU1 series vehicle class USB-C connector (lower) uses CX series (upper) as a component. Image source: Hi)
This innovative combination realizes: 1) stable and high-speed data transmission rate up to 20 Gb/s (in compliance with USB 3.2 Gen 2 × 2 standard), 2) 240 W power level (in compliance with USB power transmission 3.1 extended power range standard: 48 V, 5 A), 3) reliable connection covering the whole vehicle infotainment system; Therefore, it can support advanced functions and realize seamless system integration.
AU1 series connectors are firmly plugged, resistant to shock and heat, and can maintain reliable performance in harsh environments. In this way, the series can use this popular connector type in more challenging environments than the original design.
The series of connector assemblies support straight and right-angle mounting (Figure 2), allowing designers flexibility in wiring in a severely constrained automotive environment.
HIROSE's AU1 series connectors support straight and rectangular layout (click to enlarge)
Figure 2: AU1 series connectors support straight and rectangular layout; The demo board shows the use of connectors. Image source: Hi)
Ensure safe, accurate and correct connection
There are two unique designs for these connectors, the Connector Position Assurance (CPA) device and the deadlock key. CPACPA mechanism ensures reliable and accurate insertion. The finger-operated latch structure (Fig. 3) ensures reliable mechanical pairing and a click sound, enabling the user to confirm successful latch action.
Hirose's CPA mechanism ensures that mating connectors are fully engaged
Figure 3: The CPA mechanism ensures that mating connectors are fully engaged, then locked and secured in place and remain mated until manually disengaged. Image source: Hi)
During operation, the CPA mechanism cannot be moved until the mating is completed. When the plug is fully inserted, the receptacle will push the CPA mechanism down into the locked position indicating that the plug has been inserted as intended. To remove the matching, pull the CPA mechanism and release the auxiliary lock; An audible click is heard when disengaged.
If there is any axial or radial deviation, the two mating parts will not click to warn the user of incorrect mating. The rated mating life of these connectors exceeds 10000 mating cycles, far exceeding the expected service life in the automotive environment.
The anti-freeze key helps prevent the wrong cable from being connected to the target interface. As previously mentioned, one of the convenient features of the consumer USB-C cable is that it is reversible. This also means that they do not have a deadlock key or physical means of identification, i.e. no need to identify which plug is ultimately connected to which socket. In consumer applications where "just grab a cable" to plug in and out, the lack of a deadlock key position is an advantage. However, automotive applications are more likely to be "plugged in" and there is a risk of wiring errors when installing dense automotive cable harnesses. In these cases, such mismatches can result in a sense of frustration due to the link being inoperable, damage to peripheral devices, and potential hazards to systems and users.
To prevent erroneous wiring, the AU1 series vehicle class USB-C connectors support two physical interference key-position codes: standard (black) and "A Key" (gray/primary) (Figure 4). These two key-position layouts help ensure that mating errors do not occur in the case of two adjacent cables and connectors. Different colors also help identify these two key-position codes.
Layout of mechanical anti-freeze keys
Figure 4: The user can use one of the two mechanical key layouts to minimize cable connection errors; Connectors with standard keys are black and connectors with "A Key" are gray (male)/primary (female). Image source: Hi)
Standard and electrical performance
Specific numbers define the environmental suitability and electrical performance of these Hiconnectors. With regard to environmental suitability, these connectors operate in the temperature range of - 40 ° C to+105 ° C. They are also water and dust proof; Depending on the connector type, IP54, IP68 or IP69K protection can be achieved. IP69K is the most stringent of the three dustproof and waterproof standards.
These connectors meet USCAR-2 and USCAR-30 standards for reliability. USCAR-2 is the performance standard for automotive grade electrical connector systems, which outlines the requirements for terminals, connectors, and components in low-voltage applications on road vehicles. USCAR-30 is the performance specification for vehicle-mounted USB connection system, covering various requirements for USB connector, cable and electrical connection between consumer peripheral and vehicle-mounted USB host.
Electrically, the power supply pin (A4/A9/B4/B9 (VBUS)) is rated 1.25 A for USB-C specifications, while the non-power supply pin is rated 0.25 A for 20 VAC and VDC. The maximum initial contact resistance is 40 m Ω. After a series of standard stress tests, the contact resistance will rise slightly but not exceed 50 m Ω.