当前位置：文档库 › usb_OTG

usb_OTG

On-The-Go Supplement to the

USB 2.0 Specification

Revision 1.0a

Dec 18, 2001June 24, 2003

Revision History

Date Comment Revision Issue

0.7 11/07/2000 Revisions to all sections

0.8 04/06/2001 Revisions to all sections

0.9 09/05/2001 Revisions to all sections

1.0_rc1 10/15/2001 Minor edits to most sections

Defined T B_FS_BDIS for high speed HNP.

1.0 12/18/01 Minor edits to several sections

Defined R A_PLUG_ID and R B_PLUG_ID

1.0aRC1 11/19/2002 Updates reflected in Errata release 1

1.0aRC2 January 23, 2003 Add definition of “OTG Device”

1.0aRC3 March 25, 2003 Clarify short versus long debounce and minor edits

1.0aRC4 March 28, 2003 Add figures clarifying long and short debounce and minor edits

1.0aRC5 April 30, 2003 Clarifying changes following review at April 23 face-to-face

1.0aRC6 June 13, 2003 Set copyright information

1.0a June 24, 2003Update contributor list, correct minor editorial errors in section 6

Universal Serial Bus Specification Supplement

INTELLECTUAL PROPERTY DISCLAIMER

THIS SPECIFICATION IS PROVIDED TO YOU “AS IS” WITH NO WARRANTIES WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY, NON-INFRINGEMENT, OR FITNESS FOR ANY PARTICULAR PURPOSE. THE AUTHORS OF THIS SPECIFICATION DISCLAIM ALL

LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PROPRIETARY RIGHTS,

RELATING TO USE OR IMPLEMENTATION OF INFORMATION IN THIS SPECIFICATION. THE PROVISION OF THIS SPECIFICATION TO YOU DOES NOT PROVIDE YOU WITH ANY LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS.

All product names are trademarks, registered trademarks, or servicemarks of their respective owners.

Contributors

Glen Chandler, Advanced-Connectek (Acon) Mark Jenkins, Nokia

Chris Kolb, ARC International James Scales, Nokia

Maria Pohlman, Aten Sree Iyer, OnSpec

Ray Asbury, Cypress Semiconductor Peter Yi, Opti

Dave Cobbs, Cypress Semiconductor Bill Stanley, Palm

Kosta Koeman, Cypress Semiconductor Geert Knapen, Philips

David Wright, Cypress Semiconductor Eric Lu, Philips

Israel Zilberman, Cypress Semiconductor Chris Schell, Philips (Co-Chair)

Morten Christiansen, Ericsson Rik Stopel, Philips

Ed Beeman, Hewlett-Packard Kenneth Tan, Philips

Matt Nieberger, Hewlett-Packard Jerome Tjia, Philips

Trung Le, Imation David Wang, Philips

Eric Huang, InSilicon Hilbert Zhang, Philips

Dan Froelich, Intel Corp Keith Gallardo, Qualcomm

Venkat Iyer, Intel Corp Terry Remple, Qualcomm (Co-Chair)

Richard Lawrence, Intel Corp Joe Meza, SoftConnex

Jeff Miller, Intel Corp Dan Harmon, Texas Instruments

Francesco Liburdi, Lumberg Jeff Kacines, Texas Instruments

Ryan Hashimoto, Maxim Clarence Lewis, Texas Instruments

Paul E. Berg, MCCI Richard Nie, Texas Instruments

Terry Moore, MCCI Sue Vining, Texas Instruments

Rob Douglas, Mentor Graphics Joon Kim, TransDimension

Ian Parr, Mentor Graphics Dave Murray, TransDimension

Mark Hanson, Microsoft Jing Wang, TransDimension

Akira Aso, Molex David Wooten, Cypress

SemiconductorTransDimension Mark Carlson, Motorola Zong Liang Wu, TransDimension

Eric Overtoom, Motorola Charles Brill, Tyco Electronics

Kazumasa Saito, NEC Systems Mark Paxson, USB-IF

Esa Harma, Nokia

iii

Table of Contents

1.Introduction (1)

1.1General (1)

1.2Objective of the Supplement (1)

1.3Intended Audience (1)

2.Acronyms and Terms (3)

3.Significant Features (5)

3.1USB 2.0 Specification Compliance (5)

3.2Dual-role Device (5)

3.3Targeted Peripheral List (5)

3.4No Silent Failures (5)

3.5Supplying Current on V BUS (6)

3.6Session Request Protocol (6)

3.7Host Negotiation Protocol (6)

3.8Connectors (6)

3.9Compliant Cable Assemblies (6)

3.10Plug Overmolds (7)

3.11Cable Adapters (7)

3.12Hubs (7)

3.13Mandated Functionality (7)

4.Mechanical (9)

4.1Introduction (9)

4.2Mini-Connector Mating (9)

4.3Color Coding (10)

4.4Device, Cable and Adapter Delays (10)

4.5Compliant Usage of Connectors and Cables (11)

4.5.1Cables (11)

4.5.2Overmolds (12)

4.5.3Mechanical Interfaces (12)

4.5.4Receptacle Reference Designs (12)

4.5.5Connector Keying (12)

4.5.6Right Angle Plugs (12)

4.5.7Adapters (12)

4.6Drawings (13)

5.Electrical Requirements (33)

5.1A-Device Electrical Requirements (33)

5.1.1V BUS Output Voltage and Current (33)

5.1.2V BUS Input Impedance (33)

5.1.3V BUS Rise and Fall Time (34)

5.1.4V BUS Capacitance (34)

5.1.5V BUS Leakage Voltage (34)

5.1.6Data Line Pull-down Resistance (34)

5.1.7Data Line Pull-up Resistance (35)

5.1.8Data Line Leakage Voltage (35)

5.1.9Data Line Discharge Time (35)

5.1.10V BUS Input Current Without Battery (36)

5.2B-Device Electrical Requirements (36)

5.2.1V BUS Average Input Current (36)

5.2.2V BUS Peak Input Current (36)

iii

5.2.3V BUS Capacitance (36)

5.2.4Data Line Pull-down Resistance (36)

5.2.5Data Line Pull-up Resistance (37)

5.2.6Data Line Leakage Voltage (37)

5.2.7V BUS Input Current Without Battery (37)

5.3Session Request Protocol (37)

5.3.1Introduction (37)

5.3.2Initial Conditions (37)

5.3.3Data-line Pulsing (38)

5.3.4V BUS Pulsing (39)

5.3.5B-Device V BUS Pulsing Current (39)

5.3.6A-Device Session Valid (39)

5.3.7B-Device Session Valid (39)

5.3.8Duration of SRP (39)

5.3.9Order of Methods (40)

5.3.10Response Time of A-device (40)

5.3.11Repetition of SRP (40)

5.4Electrical Characteristics (41)

5.5Device Timings (43)

6.Host Negotiation Protocol (52)

6.1Introduction (52)

6.2Description Priority (52)

6.3HNP Overview (52)

6.4OTG Descriptor (54)

6.4.1srp_support (54)

6.4.2hnp_support (54)

6.5Set Feature Commands (54)

6.5.1b_hnp_enable (55)

6.5.2a_hnp_support (55)

6.5.3a_alt_hnp_support (56)

6.6State Machine Parameters (56)

6.6.1Inputs (56)

6.6.2Internal Variables (60)

6.6.3Outputs (60)

6.6.4Informative Variables (60)

6.6.5Timers (61)

6.6.6Test Device Support (61)

6.7Timing Summary (62)

6.7.1B-device becoming Host (62)

6.7.2A-device becoming Peripheral (62)

6.8State Diagrams (63)

6.8.1Dual-role A-Device (64)

6.8.2Dual-Role B-Device (68)

6.8.3Peripheral-Only, B-Device (70)

Figure 4-1 Mini-A to Mini-B Cable (14)

Figure 4-2 Standard-B to Mini-A Cable (15)

Figure 4-3 Mini-A to Captive Cable (16)

Figure 4-4 Mini-A Plug Overmold, Straight (17)

Figure 4-5 Mini-B Plug Overmold, Straight (18)

Figure 4-6 Mini-A Plug Interface - 1 of 2 (19)

Figure 4-7 Mini-A Plug Interface - 2 of 2 (20)

Figure 4-8 Mini-A Receptacle Interface (21)

Figure 4-9 Mini-AB Receptacle Interface (22)

Figure 4-10 Mini-A Receptacle Reference Design (23)

Figure 4-11 Mini-AB Receptacle Reference Design (24)

Figure 4-12 Mini-A Plug Blockage (25)

Figure 4-13 Mini-B Plug Blockage (26)

Figure 4-14 Mini-A Plug, Side Right Angle (27)

Figure 4-15 Mini-A Plug, Down Right Angle (28)

Figure 4-16 Mini-B Plug, Side Right Angle (29)

Figure 4-17 Mini-B Plug, Down Right Angle (30)

Figure 4-18 Adapter, Standard-A receptacle to Mini-A plug (31)

Figure 4-19 Adapter, Mini-A receptacle to Standard-A plug (32)

Figure 5-1 A-device Input Impedance (VBUS not driven) (33)

Figure 5-2 A-device SRP Timing Reference (45)

Figure 5-3 A-device HNP Timing Reference (FS) (46)

Figure 5-4 A-device HNP Timing Reference (HS) (47)

Figure 5-5 B-device SRP Timing Reference (50)

Figure 5-6 B-device HNP Timing Reference (FS) (50)

Figure 5-7 B-device HNP Timing Reference (HS) (51)

Figure 6-1 HNP Sequence of Events (53)

Figure 6-2 Dual-Role A-device State Diagram (64)

Figure 6-3 Dual-Role B-device State Diagram (68)

Figure 6-4 SRP Capable Peripheral-Only B-device State Diagram (70)

Table 4-1. Plugs Accepted By Receptacles (9)

Table 4-2. Mini-A Plug Pin Assignments (10)

Table 4-3. Color Coding for Plugs and Receptacles (10)

Table 4-4. Maximum Delay for Mini-Connector and Cable (11)

Table 4-5. Maximum Delay for Standard Connector Cable (11)

Table 5-1. DC Electrical Characteristics (41)

Table 5-2. A-device Timing (43)

Table 5-3. B-device Timing (44)

Table 5-4. Device Timing Comparison (48)

Table 6-1. OTG Descriptor (54)

Table 6-2. Set Feature Command Format (55)

Table 6-3. On-The-Go Feature Selectors (55)

Table 6-4. Dual-Role Device Timers (61)

1. Introduction

1.1 General

USB has become a popular interface for exchanging data between PC’s and peripherals. An increasing number of portable peripherals are using the USB interface to communicate with the PC. Many of these portable devices would benefit from being able to communicate to each other over the USB interface, yet certain aspects of USB make this difficult to achieve.

Specifically, USB communication can only take place between a host and a peripheral. However, in order to qualify as a PC host, a device must have several characteristics, including:

? storage for a large number of device drivers,

? the ability to source a large current, and

? a Series “A” host connector receptacle.

It is not practical for many portable devices to have all of the above characteristics, and in many cases, these characteristics are not needed in order to interface portable devices with each other.

In order to enable these limited-requirement, portable USB applications, this supplement to the USB 2.0 specification was developed that allows a portable device to take on the role of a limited USB host, without the burden of supporting all the above functions of a PC.

1.2 Objective of the Supplement

The objective of this supplement is to define a minimal set of changes to the USB 2.0 specification, such that portable USB applications are enabled.

This is not a stand-alone document. It is a supplement to the USB 2.0 specification. Any aspects of USB that are not specifically changed by this supplement are governed by the USB 2.0 specification.

1.3 Intended Audience

This specification is targeted to developers of PC peripherals and portable consumer electronic devices.

2. Acronyms and Terms

This chapter lists and defines terms and abbreviations used throughout this specification.

A-Device A device with a Standard-A or Mini-A plug inserted into its receptacle. An

A-device supplies power to V BUS; is host at the start of a session; and

under certain conditions as described in Section 6, the A-device will

relinquish the role of host to a dual-role B-device.

Application A generic term referring to any software that is running on a device that

can control the behavior or actions of the USB port(s) on a device.

B-Device A device with a Standard-B or Mini-B plug inserted into its receptacle.

The B-device is a peripheral at the start of a session. If the device is

dual-role, it may be granted the role of host from the A-device (see

Section 6).

Dual-role device A device that has the following features and characteristics:

? limited Host capability

? full-speed operation as peripheral (high-speed optional)

? full-speed support as host (low-speed and high-speed

optional)

? Targeted Peripheral List

? Session Request Protocol

? Host Negotiation Protocol

? one, and only one, Mini-AB receptacle

? minimum 8 mA output on V BUS

? means for communicating messages to the user

FS Full Speed

HS High Speed

Host A physical entity that is attached to a USB cable and is acting in the role

of the USB host as defined in the USB Specification, Revision 2.0. This

entity initiates all data transactions and provides periodic Start of Frames

(SOF’s).

HNP Host Negotiation Protocol. (See Section 6.)

ID Identification. Denotes the pin on the Mini connectors that is used to

differentiate a Mini-A plug (ID pin resistance to ground < 10?) from a

Mini-B plug (ID pin resistance to ground greater than 100 k?).

OTG On-The-Go

OTG device See Dual-role device

Peripheral A physical entity that is attached to a USB cable and is currently

operating as a “device” as defined in the USB Specification, Revision 2.0.

The Peripheral responds to low level bus requests from the Host.

SE0 Single Ended Zero

Session The period of time that V BUS is above a device’s session valid threshold.

For an A-device, the session valid threshold is V A_SESS_VLD, while for a

B-device it is V B_SESS_VLD.

SOF Start of Frame

SRP Session Request Protocol

Targeted Peripheral List A list of USB peripherals that a particular dual-role device can support when it is acting as a host.

USB Universal Serial Bus

USB-IF USB Implementers Forum

3. Significant Features

This section identifies the significant features of the OTG supplement. The purpose of this section is not to present all the technical details associated with each major feature, but rather to highlight its

existence. Where appropriate, this section references other parts of the document where further details can be found.

3.1 USB 2.0 Specification Compliance

Any device with OTG features is first and foremost a USB peripheral that is compliant with the USB 2.0 specification.

3.2 Dual-role Device

In addition to being a fully compliant USB 2.0 peripheral, a dual-role device must include the following features and characteristics:

? a limited Host capability

? full-speed operation as a peripheral (high-speed optional)

? full-speed support as a host (low-speed and high-speed optional)

? Targeted Peripheral List

? Session Request Protocol

? Host Negotiation Protocol

? one, and only one, Mini-AB receptacle

? minimum 8 mA output on V BUS

? means for communicating messages to the user

3.3 Targeted Peripheral List

When acting as Host, a dual-role device is not required to support operation with all other types of USB peripherals. It is up to the manufacturer of each dual-role device to determine what peripherals the dual-role device will support and provide a list of those peripherals. This is the called the dual-role device’s “Targeted Peripheral List”.

In its most primitive form, the Targeted Peripheral List is simply a list of peripherals, where each

peripheral is identified by a manufacturer, the kind of the device, and a model number.

The Targeted Peripheral List may also contain defined OTG peripheral types, such as an “OTG

keyboard”, or an “OTG camera”, etc. In order to qualify as a member of one of these OTG peripheral types, a peripheral would need to exhibit the electrical and software characteristics defined for that OTG peripheral type.

3.4 No Silent Failures

Whenever the cabling allows USB devices to be connected, and the devices do not support the type of communication being requested by the user, then the devices shall provide messages to the user that allow him or her to understand the problem, and correct it if possible. Insofar as is possible, the

messages shall be self explanatory, and shall not require the user to reference a manual or other

additional material.

For example, if a B-device generates SRP, the A-device may try to give control to the B-device by trying to enable HNP. The B-device may not be HNP capable. The A-device may determine that the B-device is not HNP capable because the B-device is LS or because the B-device STALL’s the command that enables HNP. When the A-device determines that the B-device is not HNP capable and that the B-device is not supported, the A-device is responsible for providing an informative message to the user

that the B-device is not supported. If, however, the B-device is HNP capable and it will have

responsibility for informing the user if the A-device is not supported.

3.5 Supplying Current on V BUS

A dual-role device must be able to source a minimum of 8 mA on V BUS when it is the A-device and a

session is in progress.

3.6 Session Request Protocol

The OTG supplement defines a Session Request Protocol (SRP), which allows a B-device to request the A-device to turn on V BUS and start a session. This protocol allows the A-device, which may be battery powered, to conserve power by turning V BUS off when there is no bus activity while still providing

a means for the B-device to initiate bus activity.

Any A-device, including a PC or laptop, is allowed to respond to SRP. Any B-device, including a

standard USB peripheral, is allowed to initiate SRP. A dual-role device is required to be able to initiate and respond to SRP.

The details of this protocol are found in Section 5.3.

3.7 Host Negotiation Protocol

The Host Negotiation Protocol (HNP) allows the Host function to be transferred between two directly connected dual-role devices and eliminates the need for a user to switch the cable connections in order to allow a change in control of communications between the devices. HNP will typically be initiated in response to input from the user or an Application on the dual-role B-device. HNP may only be

implemented through the Mini-AB receptacle on a device.

3.8 Connectors

The USB 2.0 specification defines the following connectors:

? Standard-A plug and receptacle,

? Standard-B plug and receptacle, and

? Mini-B plug and receptacle.

The OTG supplement defines the following additional connectors:

? Mini-A plug and receptacle, and

? Mini-AB receptacle.

The Mini-A receptacle can only be used in the Mini-A receptacle to Standard-A plug adapter defined in Section 4.5.7.1. All other uses are prohibited.

3.9 Compliant Cable Assemblies

The USB 2.0 specification defines the following cables:

? Standard-A plug to Standard–B plug,

? Standard-A plug to Mini-B plug, and

? Captive cable with Standard-A plug.

The OTG supplement defines the following additional cables:

? Mini-A plug to Mini-B plug,

? Mini-A plug to Standard-B plug, and

? Captive cable with Mini-A plug.

No other types of cables are allowed by either the USB specification, or by the OTG supplement.

Cables are not allowed to have receptacles on either end unless they meet the mechanical and electrical requirements of adapters defined in Section 4.5.7.

3.10 Plug Overmolds

The USB 2.0 specification limits the maximum size of the overmold for the Mini-B plug on the Standard-

A to Mini-

B cable, but it does not define the shape of the overmold. The OTG supplement constrains the

size and the shape of the overmolds for the Mini-A plug. This supplement also constrains the size and shape of the overmolds for the Mini-B plugs if those plugs are used on any of the new cables specified in this supplement.

The Mini-A plug’s overmold has an oval theme, and the Mini-B plug’s overmold has a rectangular theme.

This allows easy recognition and differentiation of the two plugs by the consumer.

3.11 Cable Adapters

The OTG supplement defines the following cable adapters:

? Mini-A receptacle to Standard-A plug, and

? Standard-A receptacle to Mini-A plug.

The first adapter allows a captive cable device with a Mini-A plug to be connected to a standard host.

The second adapter allows a captive cable device with a Standard-A plug to be connected to a dual-role device.

The physical and electrical properties of cable adapters are defined in Section 4.5.7.

3.12 Hubs

Dual-role devices may support hubs. However, the signaling methods used for the Session Request Protocol and the Host Negotiation Protocol are not handled by standard USB hubs. Therefore, when an A-device is directly connected to a standard hub, the A-device is prohibited from issuing a command that would enable the downstream device to expect or initiate HNP.

3.13 Mandated Functionality

Any device with a Mini-AB receptacle shall meet all of the requirements and provide all the functionality of a dual-role device.

4. Mechanical

This chapter provides the mechanical and electrical specifications for the cables, connectors, and cable assemblies used to interconnect devices.

4.1 Introduction

The USB 2.0 specification defines three connector pairs:

? Standard-A plug and receptacle for the host;

? Standard-B plug and receptacle for the peripheral; and

? Mini-B plug and receptacle as alternative connectors for the peripheral.

This supplement defines the following connector components:

? Mini-A plug,

? Mini-A receptacle, and

? Mini-AB receptacle.

The Mini-AB receptacle accepts either a Mini-A plug or a Mini-B plug.

This supplement defines the use of the new connector components on cables and adapters and permits the following combinations:

? Mini-A plug to Mini-B plug cable,

? Mini-A plug to Standard-B plug cable,

? Mini-A plug to captive cable,

? Mini-A receptacle to Standard-A plug adapter, and

? Standard-A receptacle to Mini-A plug adapter.

Constraints on the design of the overmolds for the Mini-A plugs are provided in this section.

Additionally, new constraints are placed on the design of the overmold for the Mini-B plugs when used on a cable that also has a Mini-A plug.

4.2 Mini-Connector Mating

The following table summarizes the plugs accepted by each of the receptacles.

Table 4-1. Plugs Accepted By Receptacles

Receptacle Plugs

Accepted

Standard-A Standard-A

Standard-B Standard-B

Mini-B Mini-B

Mini-A Mini-A

Mini-AB Mini-A or Mini-B

The usage and wiring assignments of the five pins in the Mini-A plug are defined in the following table.

Table 4-2. Mini-A Plug Pin Assignments

Contact Number Signal Name Typical Wiring

Assignment

1 VBUS Red

2 D- White

3 D+ Green

4 ID < 10 ? to GND

5 GND Black

Shell Shield Drain

Wire

The ID pin on a Mini-A plug shall be connected to the GND pin. The ID pin on a Mini-B plug is not connected or is connected to ground by a resistance of greater than R B_PLUG_ID. A dual-role device is required to be able to detect whether a Mini-A or Mini-B plug is inserted by determining if the ID pin resistance to ground is less than R A_PLUG_ID or if the resistance to ground is greater than R B_PLUG_ID.

Any ID resistance less than R A_PLUG_ID shall be treated as ID = FALSE and any resistance greater than R B_PLUG_ID shall be treated as ID = TRUE.

4.3 Color Coding

The following colors are mandated for the plastic inside the Mini connectors defined in this supplement.

Table 4-3. Color Coding for Plugs and Receptacles

Connector Color

Mini-A receptacle White

Mini-A plug White

Mini-B receptacle Black

Mini-B plug Black

Mini-AB receptacle Gray

4.4 Device, Cable and Adapter Delays

In Figure 7-11 of the USB 2.0 specification, four test planes are defined along the transmission path from the host transceivers to the peripheral transceivers. These test planes (TP) are as follows:

? TP1: pins of host transceiver chip

? TP2: contact points of host Standard-A receptacle

? TP3: contact points of peripheral Standard-B or Mini-B receptacle

? TP4: pins of peripheral transceiver chip

Section 7.1.16 of the USB 2.0 specification states that the maximum allowed delays between these test

planes are:

? TP1 to TP2: 3 ns

? TP2 to TP3: 26 ns

? TP3 to TP4: 1 ns

Since the OTG supplement allows the addition of an adapter to a cable, the delays between the test

planes for dual-role devices needs to be modified so that the maximum total delay between TP1 and

TP4 is 30 ns. The limits are as follows:

? Dual-role device - TP1 to TP2: 1 ns

? Adapter: 1

? Any cable with a Mini-A plug: 25 ns

The maximum delays for the two worst cases of connection are shown in the following tables.

Table 4-4. Maximum Delay for Mini-Connector and Cable

Time

Location Delay

USB 2.0 Compliant Host – TP1 to TP2 3 ns

Standard-A plug to Mini-A receptacle adapter 1 ns

Mini-A plug to Mini-B plug cable 25 ns

USB 2.0 Compliant B-device – TP3-TP4 1 ns

Total 30

Table 4-5. Maximum Delay for Standard Connector Cable

Time

Location Delay

On-The-Go Compliant Dual-Role Device – TP1 to

1 ns

TP2

Mini-A plug to Standard-A receptacle adapter 1 ns

Standard-A plug to Standard-B plug cable 26 ns

USB 2.0 Compliant B-device – TP3 to TP4 1 ns

ns Total 29

4.5 Compliant Usage of Connectors and Cables

Cable assemblies and connectors not described below or not allowed by other amendments to the USB

specification are not compliant with the USB specification and may not be labeled as such.

4.5.1 Cables

The new cables allowed by the OTG supplement are shown in Figure 4-1, Figure 4-2 and Figure 4-3. A

cable with a Mini-A plug must have a propagation delay of 25 ns or less, have a physical length of no

more than 4.5 meters, and meet all other requirements of a USB cable.

4.5.2 Overmolds

The size and shape of the Mini-A plug overmold must conform to the constraints shown in Figure 4-4.

The size of a Mini-B plug used on a Standard-A to Mini-B cable must conform to the constraints shown in Figure 6-10 in the Engineering Change Notice #1 of the USB Specification, version 2.0.

The size and shape of a Mini-B plug used in any other cable or adapter assembly must conform to the constraints shown in Figure 4-5.

It is recommended that all new designs for the Mini-B plug overmold follow the constraints in Figure 4-5.

Interfaces

4.5.3 Mechanical

The mechanical interfaces for the Mini-A plug, Mini-A receptacle and Mini-AB receptacle are shown in Figure 4-6, Figure 4-7, Figure 4-8 and Figure 4-9.

4.5.4 Receptacle Reference Designs

Figure 4-10 and Figure 4-11 show reference designs for the Mini-A and Mini-AB receptacles

respectively. By following these recommendations, receptacles from different manufacturers can be used interchangeably on the same printed circuit boards.

Keying

4.5.5 Connector

This Mini connector series has been designed so as to prevent the Mini-A and Mini-B plugs from being incorrectly inserted into a receptacle. The amount of metal blocking various possible incorrect insertions is shown in Figure 4-12 and Figure 4-13, and is always greater than 0.35 mm.

4.5.6 Right Angle Plugs

The overmolds for right angle plugs are required to comply with the same shape constraints that apply to straight plugs. Reference drawings for right angle plugs are shown in Figure 4-14, Figure 4-15, Figure 4-16 and Figure 4-17.

4.5.7 Adapters

The following adapters are permitted; all others are prohibited.

The propagation delay of the adapter shall be less than 1 ns. The physical length shall not exceed 150 mm. The resistance of the adapter through V BUS and GND, including contacts, shall not exceed 70 m?.

The only compliant adapters are:

? Standard-A receptacle to Mini-A plug, and

? Mini-A receptacle to Standard-A plug.

The reasons for not allowing a Series-B adapter include:

? all legal connection topologies can be achieved with the defined cables and adapters, and

? a Series-B adapter would make it possible to exceed the maximum TP1 to TP4 delay of 30 ns.