1、USB 2.0 Specification Engineering Change Notice (ECN) #1: Mini-B connectorDate: 10/20/2000Reason for ECN:The USB 2.0 specified device-side connector the B connector is too large for use witha new generation of handheld and mobile devices, e.g., cell phones which would benefitfrom connectivity to the
2、 PC. This ECN incorporates a specification of a device-side miniconnector (hereafter referred to as a mini-B connector). The new connector only appliesto upstream facing ports, i.e., connectors on devices.Summary of ECN:The bulk of the ECN specifies the mechanical requirements for the mini-B plug,re
3、ceptacle and cable assembly. It also identifies the usage scope of this connector. Thelast part of the ECN describes the minimum test criteria and performance requirementsfor the new connector.Benefits of ECN:The ECN enables standardization of miniature device-side USB connectors andconsequent econo
4、mies of scales and lower cost for a new and growing class of deviceswhich will benefit from connectivity to the PC. The standardization also allowsleveraging of the compliance test and certification model which is already in place forUSB connectors.Assessment of Impact on Current Specification and C
5、urrent USB Products:The connector specified in the ECN will not have any impact on hardware or software ofexisting USB products. The current USB spec already allows for vendor-specific deviceside connectors such cable assemblies are called captive assemblies. All that the ECNdoes is to identify one
6、such connector for use in devices which need the smaller size ofconnector. There is a potential for some end-user confusion because of two standardcable options; but this can be mitigated by appropriate end-user education.Structure of ECN:The ECN is in the form of a new Chapter 6 with the mini-B con
7、nector requirementsinserted into the appropriate locations. This format enables specification of the newconnector in context.Universal Serial Bus Specification Revision 2.085Chapter 6MechanicalThis chapter provides the mechanical and electrical specifications for the cables, connectors, and cableass
8、emblies used to interconnect USB devices. The specification includes the dimensions, materials,electrical, and reliability requirements. This chapter documents minimum requirements for the externalUSB interconnect. Substitute material may be used as long as it meets these minimums.6.1 Architectural
9、OverviewThe USB physical topology consists of connecting the downstream hub port to the upstream port of anotherhub or to a device. The USB can operate at three speeds. High-speed (480 Mb/s) and full-speed (12 Mb/s)require the use of a shielded cable with two power conductors and twisted pair signal
10、 conductors. Low-speed (1.5 Mb/s) recommends, but does not require the use of a cable with twisted pair signal conductors.The connectors are designed to be hot plugged. The USB Icon on the plugs provides tactile feedbackmaking it easy to obtain proper orientation.6.2 Keyed Connector ProtocolTo minim
11、ize end user termination problems, USB uses a “keyed connector” protocol. The physicaldifference in the Series “A” and “B” (or “mini-B”) connectors insures proper end user connectivity. The“A” connector is the principle means of connecting USB devices directly to a host or to the downstreamport of a
12、 hub. All USB devices must have the standard Series “A” connector specified in this chapter. The“B” (or “mini-B”) “B” connector allows device vendors to provide a standard detachable cable. Thisfacilitates end user cable replacement. Figure 6-1Figure 6-1 illustrates the keyed connector protocol.Univ
13、ersal Serial Bus Specification Revision 2.086Series “A“ Connectors Series “B“ Connectors Series “A“ plugs arealways oriented upstreamtowards the Host System Series “B“ plugs arealways orienteddownstream towards theUSB Device“A“ Plugs(From theUSB Device)“B“ Plugs(From theHost System)“B“ Receptacles(U
14、pstream Input to theUSB Device or Hub)“A“ Receptacles(Downstream Outputfrom the USB Host orHub)Series “mini-B“ Connectors Series “mini-B“ plugs are always oriented downstream towards the USB Device “mini-B“ Plugs (From the Host System) “mini-B“ Receptacles (Upstream Input to the USB Device or Hub) F
15、igure 6-1. Keyed Connector ProtocolUniversal Serial Bus Specification Revision 2.087The following list explains how the plugs and receptacles can be mated: Series “A” receptacle mates with a Series “A” plug. Electrically, Series “A” receptacles function asoutputs from host systems and/or hubs. Serie
16、s “A” plug mates with a Series “A” receptacle. The Series “A” plug always is oriented towardsthe host system. Series “B” receptacle mates with a Series “B” plug (male). Electrically, Series “B” receptaclesfunction as inputs to hubs or devices. Series “B” plug mates with a Series “B” receptacle. The
17、Series “B” plug is always oriented towardsthe USB hub or device. Series “mini-B” receptacle mates with a Series “mini-B” plug (male). Electrically, Series “mini-B”receptacles function as inputs to hubs or devices. Series “mini-B” plug mates with a Series “mini-B” receptacle. The Series “mini-B” plug
18、 is alwaysoriented towards the USB hub or device.6.3 CableUSB cable consists of four conductors, two power conductors, and two signal conductors.High-/full-speed cable consists of a signaling twisted pair, VBUS, GND, and an overall shield. High-/full-speed cable must be marked to indicate suitabilit
19、y for USB usage (see Section 6.6.2). High-/full-speedcable may be used with either low-speed, full-speed, or high-speed devices. When high-/full-speed cable isused with low-speed devices, the cable must meet all low-speed requirements.Low-speed recommends, but does not require the use of a cable wit
20、h twisted signaling conductors.6.4 Cable AssemblyThis specification describes three USB cable assemblies: standard detachable cable, high-/full-speedcaptive cable, and low-speed captive cable.A standard detachable cable is a high-/full-speed cable that is terminated on one end with a Series “A” plug
21、and terminated on the opposite end with a series “B” (or “mini-B”) “B” plug. A high-/full-speed captivecable is terminated on one end with a Series “A” plug and has a vendor-specific connect means (hardwiredor custom detachable) on the opposite end for the high-/full-speed peripheral. The low-speed
22、captive cableis terminated on one end with a Series “A” plug and has a vendor-specific connect means (hardwired orcustom detachable) on the opposite end for the low-speed peripheral. Any other cable assemblies areprohibited.The color used for the cable assembly is vendor specific; recommended colors
23、 are white, grey, or black.6.4.1 Standard Detachable Cable AssembliesHigh-speed and full-speed devices can utilize the “B” (or “mini-B”) “B” connector. This allows the deviceto have a standard detachable USB cable. This eliminates the need to build the device with a hardwiredcable and minimizes end
24、user problems if cable replacement is necessary.Devices utilizing the “B” (or “mini-B”) “B” connector must be designed to work with worst casemaximum length detachable cable. Standard detachable cable assemblies may be used only on high-speedand full-speed devices. Using a high-/full-speed standard
25、detachable cable on a low-speed device mayexceed the maximum low-speed cable length.Figure 6-2Figure 6-2 and Figure 6-3 illustrates a standard detachable cable assembliesy.Universal Serial Bus Specification Revision 2.088CSeries “A“ Plug to Series “B“ PlugUSB Standard DetachableCable AssemblySIZE DR
26、AWING NUMBER REVA N/ADATE2/98SCALE: N/A SHEET 1 of 1HGFEDCBA87654321HGFEDCBA87654321Detail B - B(Series “B“ Plug)Detail A - A(Series “A“ Plug)213412.032.09.010.511.5341227.012.09.07.515.7Optional MoldedStrain ReliefAll dimensions are in millimeters (mm)unless otherwise noted.Dimensions are TYPICAL a
27、nd are forgeneral reference purposes only.Aluminum Metallized Polyester Inner ShieldBlack (Ground)28 AWG STC Drain Wire 65% Tinned Copper Braided ShieldPolyvinyl Chloride (PVC) JacketGreen (D +)White (D -)Red (VBUS)Detail C - C(Typical USB Shielded Cable)IMPORTANT NOTICE: All standard detachable cab
28、le assemblies must behigh-/full-speed.CCCCAABBOvermolded Series “B“ Plug(Always downstream towards the USB Device.)Overmolded Series “A“ Plug(Always upstream towards the “host“ system.)Figure 6-22. USB Standard Detachable Cable Assembly Universal Serial Bus Specification Revision 2.089Figure 6- 3. U
29、SB Standard Mini-connector Detachable Cable AssemblyUniversal Serial Bus Specification Revision 2.090Standard detachable cable assemblies must meet the following electrical requirements: The cable must be terminated on one end with an overmolded Series “A” plug and the opposite end isterminated with
30、 an overmolded Series “B” (or “mini-B”) “B” plug. The cable must be rated for high-speed and full-speed. The cable impedance must match the impedance of the high-speed and full-speed drivers. The driversare characterized to drive specific cable impedance. Refer to Section 7.1.1 for details. The maxi
31、mum allowable cable length is determined by signal pair attenuation and propagation delay.Refer to Sections 7.1.14 and 7.1.17 for details. Differences in propagation delay between the two signal conductors must be minimized. Refer toSection 7.1.3 for details. The GND lead provides a common ground re
32、ference between the upstream and downstream ports.The maximum cable length is limited by the voltage drop across the GND lead. Refer to Section 7.2.2for details. The minimum acceptable wire gauge is calculated assuming the attached device is highpower. The VBUS lead provides power to the connected d
33、evice. For standard detachable cables, the VBUSrequirement is the same as the GND lead.6.4.2 High-/full-speed Captive Cable AssembliesAssemblies are considered captive if they are provided with a vendor-specific connect means (hardwired orcustom detachable) to the peripheral. High-/full-speed hardwi
34、red cable assemblies may be used with eitherhigh-speed, full-speed, or low-speed devices. When using a high-/full-speed hardwired cable on a low-speed device, the cable must meet all low-speed requirements.Figure 6-3 Figure 6-4 illustrates a high-/full-speed hardwired cable assembly.Universal Serial
35、 Bus Specification Revision 2.091CSeries “A“ Plug to Cut EndUSB High-/full-speedHardwired Cable AssemblySIZE DRAWING NUMBER REVA N/ADATE2/98SCALE: N/A SHEET 1 of 1HGFEDCBA87654321HGFEDCBA87654321Cut End(Always downstream towards the USB Device.)Overmolded Series “A“ Plug(Always upstream towards the
36、“host“ system.)All dimensions are in millimeters (mm)unless otherwise note.Dimensions are TYPICAL and are forgeneral reference purposes only.AABBBlunt Cut Termination(Length Dimension Point)Polyvinyl Chloride (PVC) JacketBlunt Cut Termination Prepared TerminationMetallized Mylar Inner Shield 65% Tin
37、ned Copper BraidedShieldPolyvinyl Chloride (PVC) JacketRed (VBUS)Black (Ground)Green (D +)White (D -)28 AWG STC Drain WireUser SpecifiedLength Dimension PointDetail B - B (Typical Terminations)Detail A - A(Series “A“ Plug)123427.012.09.07.515.7Optional MoldedStrain ReliefFigure 6-36-4. USB High-/ful
38、l-speed Hardwired Cable Assembly Universal Serial Bus Specification Revision 2.092High-/full-speed captive cable assemblies must meet the following electrical requirements: The cable must be terminated on one end with an overmolded Series “A” plug and the opposite end isvendor specific. If the vendo
39、r specific interconnect is to be hot plugged, it must meet the sameperformance requirements as the USB “B” connector. The cable must be rated for high-speed and full-speed. The cable impedance must match the impedance of the high-speed and full-speed drivers. The driversare characterized to drive sp
40、ecific cable impedance. Refer to Section 7.1.1 for details. The maximum allowable cable length is determined by signal pair attenuation and propagation delay.Refer to Sections 7.1.14 and 7.1.17 for details. Differences in propagation delay between the two signal conductors must be minimized. Refer t
41、oSection 7.1.3 for details. The GND lead provides a common reference between the upstream and downstream ports. Themaximum cable length is determined by the voltage drop across the GND lead. Refer to Section 7.2.2for details. The minimum wire gauge is calculated using the worst case current consumpt
42、ion. The VBUS lead provides power to the connected device. The minimum wire gauge is vendor specific.6.4.3 Low-speed Captive Cable AssembliesAssemblies are considered captive if they are provided with a vendor-specific connect means (hardwired orcustom detachable) to the peripheral. Low-speed cables
43、 may only be used on low-speed devices.Figure 6-4Figure 6-5 illustrates a low-speed hardwired cable assembly.Universal Serial Bus Specification Revision 2.093CSeries “A“ Plug to Cut EndUSB Low-speedHardwired Cable AssemblySIZE DRAWING NUMBER REVA N/ADATE2/98SCALE: N/A SHEET 1 of 1HGFEDCBA87654321HGF
44、EDCBA87654321Detail A - A(Series “A“ Plug)123427.012.09.07.515.7Optional MoldedStrain ReliefAll dimensions are in millimeters (mm)unless otherwise noted.Dimensions are TYPICAL and are forgeneral reference purposes only.AABBCut End(Always downstream towards the USB Device.)Overmolded Series “A“ Plug(
45、Always upstream towards the “host“ system.)IMPORTANT NOTICE: For use in low-speed applications only.Detail B - B (Typical Terminations)Blunt Cut Termination(Length Dimension Point)Polyvinyl Chloride (PVC) JacketBlunt Cut Termination Prepared TerminationBlack (Ground)User SpecifiedLength Dimension Po
46、intRed (VBUS)White (D -)Green (D +)Polyvinyl Chloride (PVC) JacketFigure 6-46-5. USB Low-speed Hardwired Cable Assembly Universal Serial Bus Specification Revision 2.0956.5 Connector Mechanical Configuration and Material RequirementsThe USB Icon is used to identify USB plugs and the receptacles. Fig
47、ure 6-5Figure 6-6 illustrates the USBIcon.L0.5 LLLL0.33 L0.33 L0.33 LL1.50 L1.50 L1.67 L2.33 L3.75 L5.00 L5.17 L6.25 L8.00 LDia:1.67 LLDia:1.33 LDia:LDia:LDia:LDia:LDia:1.33 LAll dimensions are 5%Figure 6-5Figure 6-6 . USB Icon 6.5.1 USB Icon LocationThe USB Icon is embossed, in a recessed area, on
48、the topside of the USB plug. This provides easy userrecognition and facilitates alignment during the mating process. The USB Icon and Manufacturers logoshould not project beyond the overmold surface. The USB Icon is required, while the Manufacturers logois recommended, for both Series “A” and “B” (o
49、r “mini-B”) “B” plug assemblies. The USB Icon is alsolocated adjacent to each receptacle. Receptacles should be oriented to allow the Icon on the plug to bevisible during the mating process. Figure 6-6Figure 6-7 and Figure 6-8 illustrates the typical plugorientations.Universal Serial Bus Specification Revision 2.096ManufacturersEngraved LogoAATop ViewOptional Top“Locator Detail“Optional Top“Locator Detail“LocatorHeightApproximately0.6mm(0.024“)Locator WidthApproximately0.5mm(0.020“)4321Engraved USBIconSection A - A(Plug Cross-Section)Overmolding
