2024年2月10日发(作者：)
Universal Serial Bus 3.1 Specification, Revision 1.0
5.3 Connector Mating Interfaces
This section defines the connector mating interfaces, including the connector interface drawings,
pin assignments, and descriptions.
5.3.1
5.3.1.1
USB 3.1 Standard-A Connector
Interface Definition
Figure 5-1 and Figure 5-2 show the USB 3.1 Standard-A receptacle and required ground spring
mating areas, respectively. Figure 5-4 shows the Standard-A plug interface dimensions for
USB 3.1. Only the dimensions that govern the mating interoperability are specified. All REF
dimensions are informative.
The Universal Serial Bus Power Delivery Specifiation defines the mechanical and electrical
requirements for the Insertion Detect feature to support cold socket capability. It may be
implemented in a Standard-A receptacle or a PD Standard-A receptacle. Implementation is vendor-specific. The Insertion Detect feature shall be implemented for cold socket Standard-A applications
and is optional for all other Standard-A implementations. See the Universal Serial Bus Power
Delivery Specifiation for complete Insertion Detect requirements. Example connector
configurations including Insertion Detect features are shown in Figure 5-3.
Although the USB 3.1 Standard-A connector has basically the same form factor as the USB 2.0
Standard-A connector, it has significant differences inside. Below are the key features and design
areas that need attention:
• In addition to the Vbus, D-, D+, and GND pins that are required for USB 2.0, the USB 3.1
Standard-A connector includes five more pins: two differential signal pairs plus one ground
(GND_DRAIN). The two added differential signal pairs are for SuperSpeed data transfer,
supporting dual simplex SuperSpeed signaling. The added GND_DRAIN pin is for drain wire
termination and managing EMI, RFI, and signal integrity.
• The contact areas of the five SuperSpeed pins are located towards the front of the receptacle as
blades, while the four USB 2.0 pins towards the back of the receptacle as beams or springs.
Accordingly, in the plug, the SuperSpeed contacts are beams located behind the USB 2.0
blades. In other words, the USB 3.1 Standard-A connector has a two-tier contact system.
• The tiered-contact approach within the Standard-A connector form factor results in less contact
area as compared to the USB 2.0 Standard-A connector. The connector interface dimensions
take into consideration contact mating requirements between the USB 3.1 Standard-A
receptacle and USB 3.1 Standard-A plug, the USB 3.1 Standard-A receptacle and USB 2.0
Standard-A plugs, and the USB 2.0 Standard-A receptacles and USB 3.1 Standard-A plug.
• The connector interface definition avoids shorting between the SuperSpeed and USB 2.0 pins
during insertion when plugging a USB 2.0 Standard-A plug into a USB 3.1 Standard-A
receptacle or a USB 3.1 Standard-A plug into a USB 2.0 Standard-A receptacle.
• There may be some increase in the USB 3.1 Standard-A receptacle connector depth (into a
system board) to support the two-tiered-contacts as compared to the USB 2.0 Standard-A
receptacle.
• Drawings for stacked USB 3.1 Standard-A receptacles are not shown in this specification.
They are allowed as long as they meet all the electrical and mechanical requirements defined in
this specification. When designing a stacked USB 3.1 Standard-A receptacle, efforts need to be
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made to minimize impedance discontinuity of the top connector in the stack because of its long
electrical path. Attention to the high speed electrical design of USB 3.1 Standard-A connectors
is required. In addition to minimizing the connector impedance discontinuities, crosstalk
between the SuperSpeed differential signal pairs and USB 2.0 D+/D- pair should also be
minimized.
• The receptacle connector should have a back-shield to ensure that the receptacle connector is
fully enclosed. The USB 3.1 receptacle should also make good contact to the PCB ground by
providing sufficient number of ground tabs to ensure a low impedance path to PCB ground.
The USB 3.1 receptacle connector should have a robust mating interface to the shield of the
USB 3.1 plug when it is inserted. Previous versions of this specification required providing a
grounding spring tab in the middle of the side closest to the USB SuperSpeed signal contacts
and grounding springs on both sides of the shell for USB 3.0 Standard-A receptacles. New
designs shall have three grounding spring tabs on the side closest to the USB SuperSpeed signal
contacts, two grounding spring tabs on the side opposite the USB SuperSpeed signal contacts,
and a grounding spring on both sides of the shell of the USB 3.1 Standard-A receptacle. See
Figure 5-2.
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Figure 5-1. USB 3.1 Standard-A Receptacle Interface Dimensions
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Universal Serial Bus 3.1 Specification, Revision 1.0
TOP VIEW (SIDE NEAREST SUPERSPEED
CONTACTS)
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EMI
contact
zones
BOTTOM VIEW (SIDE OPPOSITE SUPERSPEED
CONTACTS)
Figure 5-2. Example USB 3.1 Standard-A Receptacle with Grounding Springs and Required
contact zones on the Standard-A Plug.
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Universal Serial Bus 3.1 Specification, Revision 1.0
Insertion detect pinsDetect circuit is closed after a
mating part is insertedDetect circuitSpring fingers on the side of
receptacle shell are EMI functional
Figure 5-3. Example USB 3.1 Standard-A Mid-Mount Receptacles with Insertion Detect
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Figure 5-4. USB 3.1 Standard-A Plug Interface Dimensions
5.3.1.2 USB 3.1 Standard-A Reference Footprints
This specification does not define standard footprints. Any footprint may be used as long as all
mechanical and electrical requirements are met. Example footprints are provided for reference
only.
Figure 5-5 shows through-hole example footprints for the USB 3.1 Standard-A receptacle with a
back-shield. Pin numbers are marked.
Figure 5-6 shows an example footprint for a mid-mount standard mount (mounted on the top of the
PCB) Standard-A receptacle that includes Insertion Detect.
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Universal Serial Bus 3.1 Specification, Revision 1.0
Figure 5-7 shows an example mid-mount reverse mount (mounted on the bottom of the PCB) with
Insertion Detect. The reverse mount configuration locates the SuperSpeed signals between the
USB 2.0 signals and the PCB edge, making the SuperSpeed signal routing more challenging.
See Section 5.6.1.2 for target characteristic impedance.
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Universal Serial Bus 3.1 Specification, Revision 1.0
Figure 5-5. Example Footprint for the USB 3.1 Standard-A Receptacle - Through-Hole with
Back-Shield
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Figure 5-6. Example Footprint for the USB 3.1 Standard-A Receptacle - Mid-Mount Standard
Mount Through-Hole with Insertion Detect
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Universal Serial Bus 3.1 Specification, Revision 1.0
Figure 5-7. Example Footprint for the USB 3.1 Standard-A Receptacle - Mid-Mount Reverse
Mount Through-Hole with Insertion Detect
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5.3.1.3 Pin Assignments and Description
The usage and assignments of the nine pins in the USB 3.1 Standard-A connector are defined in
Table 5-2.
Table 5-2. USB 3.1 Standard-A Connector Pin Assignments
Pin Number
1
2
3
4
5
6
7
8
9
124, 13
1Signal Name
VBUS
D-
D+
GND
StdA_SSRX-
StdA_SSRX+
GND_DRAIN
StdA_SSTX-
StdA_SSTX+
INSERTION
DETECT
2Description
Power
USB 2.0 differential pair
Ground for power return
SuperSpeed receiver differential
pair
Ground for signal return
SuperSpeed transmitter
differential pair
Receptacle only. Detects
insertion of a plug into the
receptacle. Optional except for
cold socket applications. See the
Universal Serial Bus Power
Delivery Specifiation for details.
Connector metal shell
Mating Sequence
Third
Fourth
Third
Last
3Second
Shell Shield First
Note 1: Note 1: Pin numbers not included in this table do not have contacts present.
Note 2: Tx and Rx are defined from the host perspective.
Note 3: The mating sequence assumes support of INSERTION DETECT.
Note 4: Pin 12, if present, shall be connected to Shield.
The physical location of the pins in the connector is illustrated in Figure 5-1 to Figure 5-7. Pins 1
to 4 are referred to as the USB 2.0 pins, while pins 5 to 9 are referred to as the SuperSpeed pins.
See the Universal Serial Bus Power Delivery Specifiation for location of pins 12 and 13.
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Universal Serial Bus 3.1 Specification, Revision 1.0
5.3.1.4 USB 3.1 Standard-A Connector Color Coding
Since both the USB 2.0 Standard-A and USB 3.1 Standard-A receptacles may co-exist on a host,
color coding is recommended for the USB 3.1 Standard-A connector (receptacle and plug) housings
to help users distinguish it from the USB 2.0 Standard-A connector.
Blue (Pantone 300C) is the recommended color for the USB 3.1 Standard-A receptacle and plug
plastic housings. When the recommended color is used, connector manufacturers and system
integrators should make sure that the blue-colored receptacle housing is visible to users. Figure 5-8
illustrates the color coding recommendation for the USB 3.1 Standard-A connector.
Figure 5-8. Illustration of Color Coding Recommendation for USB 3.1
Standard-A Connector
5.3.2
5.3.2.1
USB 3.1 Standard-B Connector
Interface Definition
Figure 5-9, Figure 5-10, and Figure 5-11 show the USB Standard-B receptacle dimensions, the
USB Standard-B plug dimensions, and a USB Standard-B receptacle reference footprint,
respectively. See Section 5.6.1.2 for target characteristic impedance.
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Universal Serial Bus 3.1 Specification, Revision 1.0
Figure 5-9. USB 3.1 Standard-B Receptacle Interface Dimensions
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Figure 5-10. USB 3.1 Standard-B Plug Interface Dimensions
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Universal Serial Bus 3.1 Specification, Revision 1.0
Figure 5-11. Reference Footprint for the USB 3.1 Standard-B Receptacle
The USB 3.1 Standard-B receptacle interfaces have two portions: the USB 2.0 interface and the
SuperSpeed interface. The USB 2.0 interface consists of pins 1 to 4, while the SuperSpeed
interface consists of pins 5 to 9.
When a USB 2.0 Standard-B plug is inserted into the USB 3.1 Standard-B receptacle, only the
USB 2.0 interface is engaged and the link will not take advantage of the Enhanced SuperSpeed
capability. Since the USB 3.1 SuperSpeed portion is visibly not mated when a USB 2.0 Standard-B
plug is inserted in the USB 3.1 Standard-B receptacle, users have the visual feedback that the cable
plug is not matched with the receptacle. Only when a USB 3.1 Standard-B plug is inserted into the
USB 3.1 Standard-B receptacle, is the interface completely visibly engaged.
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5.3.2.2 Pin Assignments and Description
The usage and assignments of the nine pins in the USB 3.1 Standard-B connector are defined in
Table 5-3.
Table 5-3. USB 3.1 Standard-B Connector Pin Assignments
Pin Number Signal Name
1
2
3
4
5
6
7
8
9
Shell
VBUS
D-
D+
GND
StdB_SSTX-
StdB_SSTX+
GND_DRAIN
StdB_SSRX-
StdB_SSRX+
Shield
Ground for power return
SuperSpeed transmitter
differential pair
Ground for signal return
SuperSpeed receiver differential
pair
Connector metal shell First
Second
Third or beyond
Description
Power
USB 2.0 differential pair
Mating Sequence
Second
Third or beyond
Note: Tx and Rx are defined from the device perspective.
The physical location of the pins in the connector is illustrated in Figure 5-9 to Figure 5-11.
5.3.3
5.3.3.1
USB 3.1 Micro Connector Family
Interfaces Definition
The USB 3.1 Micro connector family consists of the USB 3.1 Micro-B receptacle, USB 3.1
Micro-AB receptacle, USB 3.1 Micro-B plug, and USB 3.1 Micro-A plug. Figure 5-12 and Figure
5-13 show the USB 3.1 Micro family receptacle and plug interface dimensions, respectively. Only
dimensions that govern the mating interoperability are specified.
The USB 3.1 Micro connector family has the following characteristics:
• The USB 3.1 Micro-B connector may be considered a combination of USB 2.0 Micro-B
interface and the USB 3.1 SuperSpeed contacts. The USB 3.1 Micro-B receptacle accepts a
USB 2.0 Micro-B plug, maintaining backward compatibility.
• The USB 3.1 Micro-B connector maintains the same connector height and contact pitch as the
USB 2.0 Micro-B connector.
• The USB 3.1 Micro-B connector uses the same latch design as the USB 2.0 Micro-B connector.
• The USB 3.1 Micro-AB receptacle is identical to the USB 3.1 Micro-B receptacle except for a
keying difference in the connector shell outline.
• The USB 3.1 Micro-A plug is similar to the USB 3.1 Micro-B plug with different keying and
ID pin connections. The Universal Serial Bus Power Delivery Specifiation discusses the ID pin
connections.
There is no required footprint for the USB 3.1 Micro connector family. Figure 5-14 shows
reference Micro-B and -AB connector footprints.
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Figure 5-12. USB 3.1 Micro-B and -AB Receptacles Interface Dimensions
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Universal Serial Bus 3.1 Specification, Revision 1.0
Figure 5-13. USB 3.1 Micro-B and Micro-A Plug Interface Dimensions
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Universal Serial Bus 3.1 Specification, Revision 1.0
Figure 5-14. Reference Footprint for the USB 3.1 Micro-B or Micro-AB Receptacle
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5.3.3.2 Pin Assignments and Description
Table 5-4 and Table 5-5 show the pin assignments for the USB 3.1 Micro connector family.
Table 5-4. USB 3.1 Micro-B Connector Pin Assignments
Pin Number
1
2
3
4
5
6
7
8
9
10
Shell
Signal Name
VBUS
D-
D+
ID
GND
MicB_SSTX-
MicB_SSTX+
GND_DRAIN
MicB_SSRX-
MicB_SSRX+
Shield
Description
Power
USB 2.0 differential pair
Mating Sequence
Second
Last
OTG identification
Ground for power return
SuperSpeed transmitter
differential pair
Ground for SuperSpeed signal
return
SuperSpeed receiver differential
pair
Connector metal shell
Second
Last
Second
Last
First
Note: Tx and Rx are defined from the device perspective.
Table 5-5. USB 3.1 Micro-AB/-A Connector Pin Assignments
Pin Number
1
2
3
4
5
6
7
8
9
10
Shell
Signal Name
VBUS
D-
D+
ID
GND
MicA_SSTX-
MicA_SSTX+
GND_DRAIN
MicA_SSRX-
MicA_SSRX+
Shield
Description
Power
USB 2.0 differential pair
Mating Sequence
Second
Last
OTG identification
Ground for power return
SuperSpeed receiver differential
pair
Ground for SuperSpeed signal
return
SuperSpeed transmitter
differential pair
Connector metal shell
Second
Last
Second
Last
First
Note: Tx and Rx are defined when an OTG device serves as a host.
The physical location of the pins in the connector is illustrated in Figure 5-12 to Figure 5-14.
5.4 Cable Construction and Wire Assignments
This section discusses the USB 3.1 cables, including cable construction, wire assignments, and wire
gauges. The performance requirements are specified in Section 5.6.1.
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