USB2512B_技术文档

USB251xB/xBi

USB 2.0 Hi-Speed Hub Controller

General Description

Features

The Microchip USB251xB/xBi hub is a family of low-

power, configurable, MTT (multi transaction translator)

hub controller IC products for embedded USB solu-

tions. The x in the part number indicates the number of

downstream ports available, while the B indicates bat-

tery charging support. The Microchip hub supports low-

speed, full-speed, and hi-speed (if operating as a hi-

speed hub) downstream devices on all of the enabled

downstream ports.

• USB251xB/xBi products are fully footprint com-

patible with USB251x/xi/xA/xAi products as direct

drop-in replacements

—

Cost savings include using the same PCB

components and application of USB-IF Compliance

by Similarity

• Full power management with individual or ganged

power control of each downstream port

• Fully integrated USB termination and pull-up/pull-

down resistors

Highlights

• Supports a single external 3.3 V supply source;

internal regulators provide 1.2 V internal core volt-

age

• High performance, low-power, small footprint hub

controller IC with 2, 3, or 4 downstream ports

• Onboard 24 MHz crystal driver or external

24 MHz clock input

• Fully compliant with the USB 2.0 Specification [1]

• Enhanced OEM configuration options available

through either a single serial I²C EEPROM, or

SMBus slave port

• Customizable vendor ID, product ID, and device

ID

• 4 kilovolts of HBM JESD22-A114F ESD protection

(powered and unpowered)

• MultiTRAK^TM

- High-performance multiple transaction trans-

lator which provides one transaction transla-

tor per port

• Supports self- or bus-powered operation

• Supports the USB Battery Charging specification

Rev. 1.1 for Charging Downstream Ports (CDP)

• PortMap

• The USB251xB/xBi offers the following packages:

- 36-pin SQFN (6x6 mm) (Preferred)

- 36-pin QFN (6x6 mm) (Legacy)

- Flexible port mapping and disable sequenc-

ing

• PortSwap

• USB251xBi products support the industrial tem-

perature range of -40ºC to +85ºC

- Programmable USB differential-pair pin loca-

tions ease PCB design by aligning USB sig-

nal lines directly to connectors

• USB251xB products support the extended com-

mercial temperature range of 0ºC to +85ºC

• PHYBoost

- Programmable USB signal drive strength for

recovering signal integrity using 4-level driv-

ing strength resolution

Applications

• LCD monitors and TVs

• Multi-function USB peripherals

• PC motherboards

• Set-top boxes, DVD players, DVR/PVR

• Printers and scanners

• PC media drive bay

• Portable hub boxes

• Mobile PC docking

• Embedded systems

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 1

USB251xB/xBi

TO OUR VALUED CUSTOMERS

It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip

products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and

enhanced as new volumes and updates are introduced.

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http://www.microchip.com

You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page.

The last character of the literature number is the version number, (e.g., DS30000000A is version A of document DS30000000).

Errata

An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for cur-

rent devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the

revision of silicon and revision of document to which it applies.

To determine if an errata sheet exists for a particular device, please check with one of the following:

•

Microchip’s Worldwide Web site; http://www.microchip.com

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When contacting a sales office, please specify which device, revision of silicon and data sheet (include -literature number) you are

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DS00001692C-page 2

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

Table of Contents

1.0 Introduction ..................................................................................................................................................................................... 4

2.0 Block Diagram ................................................................................................................................................................................. 6

3.0 Pin Information ................................................................................................................................................................................ 7

4.0 Battery Charging Support ............................................................................................................................................................. 17

5.0 Initial Interface/Configuration Options ........................................................................................................................................... 19

6.0 DC Parameters ............................................................................................................................................................................. 39

7.0 AC Specifications .......................................................................................................................................................................... 44

8.0 Package Marking Information ....................................................................................................................................................... 46

9.0 Package Information ..................................................................................................................................................................... 48

Appendix A: Acronyms ........................................................................................................................................................................ 50

Appendix B: References ..................................................................................................................................................................... 51

Appendix C: Data Sheet Revision History .......................................................................................................................................... 52

The Microchip Web Site ...................................................................................................................................................................... 54

Customer Change Notification Service ............................................................................................................................................... 54

Customer Support ............................................................................................................................................................................... 54

Product Identification System ............................................................................................................................................................. 55

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 3

USB251xB/xBi

1.0

INTRODUCTION

The Microchip USB251xB/xBi hub family is a group of low-power, configurable, MTT (multi transaction translator) hub

controller ICs. The hub provides downstream ports for embedded USB solutions and is fully compliant with the USB 2.0

Specification [1]. Each of the hub controllers can attach to an upstream port as a full-speed or full-/hi-speed hub. The

hub can support low-speed, full-speed, and hi-speed downstream devices when operating as a hi-speed hub.

All required resistors on the USB ports are integrated into the hub. This includes all series termination resistors and all

required pull-down and pull-up resistors on D+ and D- pins. The over-current sense inputs for the downstream facing

ports have internal pull-up resistors.

The USB251xB/xBi hub family includes programmable features, such as:

• MultiTRAK^TMTechnology: implements a dedicated Transaction Translator (TT) for each port. Dedicated TTs help

maintain consistent full-speed data throughput regardless of the number of active downstream connections.

• PortMap: provides flexible port mapping and disable sequences. The downstream ports of a USB251xB/xBi hub

can be reordered or disabled in any sequence to support multiple platform designs with minimum effort. For any

port that is disabled, the USB251xB/xBi hub controller automatically reorders the remaining ports to match the

USB host controller’s port numbering scheme.

• PortSwap: allows direct alignment of USB signals (D+/D-) to connectors to avoid uneven trace length or crossing

of the USB differential signals on the PCB.

• PHYBoost: enables 4 programmable levels of USB signal drive strength in downstream port transceivers. PHY-

Boost will also attempt to restore USB signal integrity.

1.1

Configurable Features

The USB251xB/xBi hub controller provides a default configuration that may be sufficient for most applications. Strapping

option pins (see Section 3.3.1 on page 14) provide additional features to enhance the default configuration. When the

hub is initialized in the default configuration, the following features may be configured using the strapping options:

• Downstream non-removable ports, where the hub will automatically report as a compound device

• Downstream disabled ports

• Enabling of battery charging option on individual ports

• The USB251xB/xBi hub controllers can alternatively be configured by an external I²C EEPROM or a microcontrol-

ler as an SMBus slave device. When the hub is configured by an I²C EEPROM or over SMBus, the following con-

figurable features are provided:

• Support for compound devices on a port-by-port basis

• Selectable over-current sensing and port power control on an individual or ganged basis to match the circuit board

component selection

• Customizable vendor ID, product ID, and device ID

• Configurable USB signal drive strength

• Configurable USB differential pair pin location

• Configurable delay time for filtering the over-current sense inputs

• Configurable downstream port power-on time reported to the host

• Indication of the maximum current that the hub consumes from the USB upstream port

• Indication of the maximum current required for the hub controller

• Custom string descriptors (up to 31 characters):

- Product

- Manufacturer

- Serial number

• Battery charging USB251xB/xBi products are fully footprint compatible with USB251x/xi/xA/xAi products:

- Pin-compatible

- Direct drop-in replacement

- Use the same PCB components

- USB-IF Compliance by Similarity for ease of use and a complete cost reduction solution

- Product IDs, device IDs, and other register defaults may differ. See Section 5.1 on page 19 for details.

DS00001692C-page 4

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

TABLE 1-1:

Part

SUMMARY OF COMPATIBILITIES BETWEEN USB251XB/XBI AND

USB251X/XI/XA/XAI PRODUCTS

Drop-in Replacement

Number

USB2512

USB2512B

USB2512i

USB2512A

USB2512Ai

USB2513

USB2513i

USB2514

USB2514i

USB2512Bi

USB2512B

USB2512Bi

USB2513B

USB2513Bi

USB2514B

USB2514Bi

Conventions

Within this manual, the following abbreviations and symbols are used to improve readability.

Example

BIT

Description

Name of a single bit within a field

FIELD.BIT

x…y

Name of a single bit (BIT) in FIELD

Range from x to y, inclusive

BITS[m:n]

Groups of bits from m to n, inclusive

Pin Name

zzzzb

Binary number (value zzzz)

0xzzz

Hexadecimal number (value zzz)

zzh

Hexadecimal number (value zz)

rsvd

Reserved memory location. Must write 0, read value indeterminate

Instruction code, or API function or parameter

Section or Document name

code

Section Name

x

Don’t care

{,Parameter}

<> indicate a Parameter is optional or is only used under some conditions

Braces indicate Parameter(s) that repeat one or more times

Brackets indicate a nested Parameter. This Parameter is not real and actually

decodes into one or more real parameters.

[Parameter]

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 5

USB251xB/xBi

2.0

BLOCK DIAGRAM

FIGURE 2-1:

USB251XB/XBI HUB FAMILY BLOCK DIAGRAM

To I²C EEPROM or

SMBus master

To upstream Upstream

24 MHz

crystal

V_BUS

USB data

SDA SCK

3.3 V

VDDA

Serial

Bus-

power

detect/

1.2 V reg

PLL

interface

Upstream

PHY

V_buspulse

Serial

interface

engine

Repeater

Controller

3.3 V

TT

#x

TT

#1

Port

controller

...

1.2 V reg

VDDCR

Routing and port re-ordering logic

Port #1

Port #x

OC sense

PHY#1

PHY#x

...

switch driver/

LED drivers

switch driver/

LED drivers

OC

Port

OC

Port

power

USB data

downstream

USB data

downstream

sense power

switch/

LED

sense

switch/

LED

drivers

x indicates the number of available downstream ports: 2, 3, or 4

DS00001692C-page 6

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

3.0

PIN INFORMATION

This chapter outlines the pinning configurations for each package type available, followed by a corresponding pin list

organized alphabetically. The detailed pin descriptions are listed then outlined by function in Section 3.3, "Pin Descrip-

tions (Grouped by Function)," on page 12.

3.1

Pin Configurations

The following figures detail the pinouts of the various USB251xB/xBi versions.

FIGURE 3-1:

USB2512B PIN DIAGRAM

SUSP_IND/LOCAL_PWR/NON_REM0

NC

28

29

30

31

32

33

34

35

36

18

17

16

15

14

13

12

11

10

VDDA33

USBDM_UP

USBDP_UP

XTALOUT

XTALIN/CLKIN

PLLFILT

OCS_N2

PRTPWR2/BC_EN2

VDD33

CRFILT

USB2512B/12Bi

(Top View)

OCS_N1

PRTPWR1/BC_EN1

TEST

Ground Pad

(must be connected to VSS)

RBIAS

VDDA33

Indicates pins on the bottom of the device.

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 7

USB251xB/xBi

FIGURE 3-2:

USB2513B PIN DIAGRAM

SUSP_IND/LOCAL_PWR/NON_REM0

PRTPWR3/BC_EN3

OCS_N2

28

29

30

31

32

33

34

35

36

18

17

16

15

14

13

12

11

10

VDDA33

USBDM_UP

USBDP_UP

XTALOUT

XTALIN/CLKIN

PLLFILT

PRTPWR2/BC_EN2

VDD33

CRFILT

USB2513B/13Bi

(Top View)

OCS_N1

PRTPWR1/BC_EN1

TEST

Ground Pad

(must be connected to VSS)

RBIAS

VDDA33

Indicates pins on the bottom of the device.

DS00001692C-page 8

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

FIGURE 3-3:

USB2514B PIN DIAGRAM

SUSP_IND/LOCAL_PWR/NON_REM0

PRTPWR3/BC_EN3

OCS_N2

28

29

30

31

32

33

34

35

36

18

17

16

15

14

13

12

11

10

VDDA33

USBDM_UP

USBDP_UP

XTALOUT

XTALIN/CLKIN

PLLFILT

PRTPWR2/BC_EN2

VDD33

CRFILT

USB2514B/14Bi

(Top View)

OCS_N1

PRTPWR1/BC_EN1

TEST

Ground Pad

(must be connected to VSS)

RBIAS

VDDA33

Indicates pins on the bottom of the device.

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 9

USB251xB/xBi

3.2

Pin List (Alphabetical)

TABLE 3-1:

USB251XB/XBI PIN LIST (ALPHABETICAL)

Name

Pin Numbers

Symbol

BC_EN1

Battery Charging

Strap Option

12

16

BC_EN2

BC_EN3

-

18

BC_EN4

-

20

CFG_SEL0

CFG_SEL1

Configuration

Programming

Selection

24

25

CLKIN

External Clock Input

33

14

CRFILT

Core Regulator Filter

Capacitor

Ground Pad

(VSS)

Exposed Pad Tied to

Ground (VSS)

ePad

25

HS_IND

Hi-Speed Upstream

Port Indicator

LOCAL_PWR

Local Power

Detection

28

NC

No Connect

6

7

-

NC

18

19

NC

8

9

-

NC

20

21

NC

NON_REM0

NON_REM1

OCS_N1

OCS_N2

OCS_N3

OCS_N4

PLLFILT

Non-Removable

Port Strap Option

28

22

13

17

Over-Current Sense

-

19

-

21

PLL Regulator Filter

Capacitor

34

PRT_DIS_M1

PRT_DIS_M2

PRT_DIS_M3

PRT_DIS_M4

PRT_DIS_P1

PRT_DIS_P2

PRT_DIS_P3

PRT_DIS_P4

Downstream Port

Disable Strap Option

1

3

-

6

7

-

8

9

Port Disable

2

4

DS00001692C-page 10

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

TABLE 3-1:

USB251XB/XBI PIN LIST (ALPHABETICAL) (CONTINUED)

Pin Numbers

Symbol

Name

PRTPWR1

PRTPWR2

PRTPWR3

PRTPWR4

RBIAS

USB Port Power

Enable

12

16

-

18

-

20

USB Transceiver

Bias

35

RESET_N

SCL

Reset Input

Serial Clock

26

24

22

24

SDA

Serial Data Signal

SMBCLK

System

Management Bus

Clock

SMBDATA

SUSP_IND

System

Management Bus

22

28

Data Signal

Active/Suspend

Status Indicator

TEST

Test Pin

11

30

31

1

USBDM_UP

USBDP_UP

USBDM_DN1

USBDM_DN2

USBDM_DN3

USBDM_DN4

USBDP_DN1

USBDP_DN2

USBDP_DN3

USBDP_DN4

VBUS_DET

USB Bus Data

Hi-Speed USB Data

3

-

6

7

-

8

9

2

4

Upstream VBUS

Power Detection

27

VDD33

3.3 V Digital Power

15

23

5

VDD33

VDDA33

XTALIN

XTALOUT

3.3 V Analog Power

10

29

36

33

32

Crystal Input

Crystal Output

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 11

USB251xB/xBi

3.3

Pin Descriptions (Grouped by Function)

An N at the end of a signal name indicates that the active (asserted) state occurs when the signal is at a low voltage

level. When the N is not present, the signal is asserted when it is at a high voltage level. The terms assertion and nega-

tion are used exclusively in order to avoid confusion when working with a mixture of active low and active high signals.

The term assert, or assertion, indicates that a signal is active, independent of whether that level is represented by a high

or low voltage. The term negate, or negation, indicates that a signal is inactive.

TABLE 3-2:

Symbol

USB251XB/XBI PIN DESCRIPTIONS

Buffer

Type

Description

UPSTREAM USB 2.0 INTERFACES

USBDM_UP

USBDP_UP

IO-U

I

USB Data: connect to the upstream USB bus data signals (host, port, or upstream

hub).

VBUS_DET

Detect Upstream VBUS Power: detects the state of the upstream VBUS power.

The hub monitors VBUS_DET to determine when to assert the internal D+ pull-up

resistor: (signaling a connect event).

When designing a detachable hub, this pin should be connected to VBUS on the

upstream port via a 2:1 voltage divider. Two 100 k resistors are suggested.

For self-powered applications with a permanently attached host, this pin must be

connected to a dedicated host control output, or connected to the 3.3 V domain

that powers the host (typically VDD33).

DOWNSTREAM USB 2.0 INTERFACES

USBDP_DN[x:1]/P

RT_DIS_P[x:1]

IO-U

Hi-Speed USB Data: connect to the downstream USB peripheral devices attached

to the hub’s port. To disable, use a 10 k pull-up resistor to 3.3 V.

USBDM_DN[x:1]/P

RT_DIS_M[x:1]

Downstream Port Disable Strap Option: when enabled by package and

configuration settings (see Table 5-1 on page 19), this pin is sampled at RESET_N

negation to determine if the port is disabled.

To disable a port, pull up both PRT_DIS_M[x:1] and PRT_DIS_P[x:1] pins for the

corresponding port number(s). See Section 3.3.1, on page 14 for pull up details.

PRTPWR[x:1]/

BC_EN[x:1]

O12

IPD

USB Power Enable: enables power to USB peripheral devices downstream.

Battery Charging Strap Option: when enabled by package and configuration

settings (see Table 5-1), the pin will be sampled at RESET_N negation to

determine if ports [x:1] support the battery charging protocol. When supporting the

battery charging protocol, the hub also supports external port power controllers.

The battery charging protocol enables a device to draw the currents per the USB

battery charging specification. See Section 3.3.1, on page 14 for strap pin details.

1 : Battery charging feature is supported for port x

0 : Battery charging feature is not supported for port x

OCS_N[x:1]

RBIAS

IPU

I-R

Over-Current Sense: input from external current monitor indicating an over-current

condition.

USB Transceiver Bias: a 12.0 k (+/- 1%) resistor is attached from ground to this

pin to set the transceiver’s internal bias settings.

DS00001692C-page 12

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

TABLE 3-2:

Symbol

USB251XB/XBI PIN DESCRIPTIONS (CONTINUED)

Buffer

Description

Type

SERIAL PORT INTERFACES

I/OSD12 Serial Data Signal

System Management Bus Signal

SDA/

SMBDATA/

NON_REM1

Non-Removable Port 1 Strap Option: when enabled by package and configuration

options (see Table 5-1 on page 19), this pin will be sampled (in conjunction with

LOCAL_PWR/SUSP_IND/NON_REM0) at RESET_N negation to determine if

ports [x:1] contain permanently attached (non-removable) devices:

NON_REM[1:0] = 00 : all ports are removable

NON_REM[1:0] = 01 : port 1 is non-removable

NON_REM[1:0] = 10 : ports 1 and 2 are non-removable

NON_REM[1:0] = 11 : when available, ports 1, 2, and 3 are non-removable

When NON_REM[1:0] is chosen such that there is a non-removable device, the

hub will automatically report itself as a compound device (using the proper

descriptors).

RESET_N

IS

RESET Input: the system can reset the chip by driving this input low. The

minimum active low pulse is 1 s.

SCL/

I/OSD12 Serial Clock (SCL)

System Management Bus Clock

SMBCLK/

CFG_SEL0

Configuration Select: the logic state of this multifunction pin is internally latched

on the rising edge of RESET_N (RESET_N negation), and will determine the hub

configuration method as described in Table 5-1.

HS_IND/

I/O12

Hi-Speed Upstream Port Indicator: upstream port connection speed.

Asserted = the hub is connected at HS

Negated = the hub is connected at FS

Note:

When implementing an external LED on this pin, the active state is

indicated above and outlined in Section 3.3.1.3, on page 15.

CFG_SEL1

XTALIN

Configuration Programming Select 1: the logic state of this pin is internally latched

on the rising edge of RESET_N (RESET_N negation), and will determine the hub

configuration method as described in Table 5-1.

MISC

ICLKx

Crystal Input: 24 MHz crystal.

This pin connects to either one terminal of the crystal or to an external 24 MHz

clock when a crystal is not used.

CLKIN

External Clock Input: this pin connects to either one terminal of the crystal or to

an external 24 MHz clock when a crystal is not used.

XTALOUT

OCLKx Crystal Output: this is the other terminal of the crystal circuit with 1.2 V p-p output

and a weak (< 1mA) driving strength. When an external clock source is used to

drive XTALIN/CLKIN, leave this pin unconnected, or use with appropriate

caution.

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DS00001692C-page 13

USB251xB/xBi

TABLE 3-2:

Symbol

USB251XB/XBI PIN DESCRIPTIONS (CONTINUED)

Buffer

Type

Description

SUSP_IND/

I/O

Active/Suspend Status LED: indicates USB state of the hub.

Negated = unconfigured; or configured and in USB suspend

Asserted = hub is configured and is active (i.e., not in suspend)

LOCAL_PWR/

NON_REM0

Local Power: detects availability of local self-power source.

Low = self/local power source is NOT available (i.e., the hub gets all power from

the upstream USB VBus)

High = self/local power source is available

Non-Removable 0 Strap Option: when enabled by package and configuration

settings (see Table 5-1 on page 19), this pin will be sampled (in conjunction with

NON_REM[1]) at RESET_N negation to determine if ports [x:1] contain

permanently attached (non-removable) devices:

Note:

When implementing an external LED on this pin, the active state is

outlined below and detailed in Section 3.3.1.3, on page 15.

NON_REM[1:0] = 00 : all ports are removable; LED is active high

NON_REM[1:0] = 01 : port 1 is non-removable; LED is active low

NON_REM[1:0] = 10 : ports 1 and 2 are non-removable; LED is active high

NON_REM[1:0] = 11 : (when available) ports 1, 2, and 3 are non-removable; LED

is active low

TEST

IPD

Test Pin: treat as a no connect pin or connect to ground. No trace or signal should

be routed or attached to this pin.

POWER, GROUND, and NO CONNECTS

CRFILT

VDD Core Regulator Filter Capacitor: this pin can have up to a 0.1 F low-ESR

capacitor to VSS, or be left unconnected.

VDD33

VDDA33

PLLFILT

3.3 V Power

3.3 V Analog Power

PLL Regulator Filter Capacitor: this pin can have up to a 0.1 F low-ESR capacitor

to VSS, or be left unconnected.

VSS

NC

Ground Pad/ePad: the package slug is the only VSS for the device and must be

tied to ground with multiple vias.

No Connect: no signal or trace should be routed or attached to all NC pins.

3.3.1

CONFIGURING THE STRAP PINS

If a pin's strap function is enabled thru the hub configuration selection, (Table 5-1, “Initial Interface/Configuration

Options,” on page 19) the strap pins must be pulled either high or low using the values provided in Table 3-3. Each strap

option is dependent on the pin’s buffer type, as outlined in the sections that follow.

TABLE 3-3:

STRAP OPTION SUMMARY

Strap Option

Resistor Value

Buffer Type

Notes

Non-Removable

47 - 100 k

I/O

Internal Pull-Down

• Only applicable to port power pins

• Contains a built-in resistor

10 k

IPD

I/O

LED

47 - 100 k

DS00001692C-page 14

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

3.3.1.1

Non-Removable

If a strap pin’s buffer type is I/O, an external pull-up or pull-down must be implemented as shown in Figure 3-4. Use

Strap High to set the strap option to 1 and Stap Low to set the strap option to 0. When implementing the Strap Low

option, no additional components are needed (i.e., the internal pull-down provides the resistor).

FIGURE 3-4:

NON-REMOVABLE PIN STRAP EXAMPLE

+V

R k

I/O Strap Pin

HUB

Strap High

I/O Strap Pin

HUB

Strap Low

R k

GND

3.3.1.2

Internal Pull-Down (IPD)

If a strap pin’s buffer type is IPD (pins BC_EN[x:1]), one of the two hardware configurations outlined below must be

implemented. Use the Strap High configuration to set the strap option value to 1 and Strap Low to set the strap option

value to 0.

FIGURE 3-5:

PIN STRAP OPTION WITH IPD PIN EXAMPLE

+V

R k

IPD Strap Pin

HUB

Strap High

IPD Strap Pin

HUB

Strap Low

VSS

3.3.1.3

LED

If a strap pin’s buffer type is I/O and shares functionality with an LED, the hardware configuration outlined below must

be implemented. The internal logic will drive the LED appropriately (active high or low) depending on the sampled strap

option. Use the Strap High configuration to set the strap option value to 1 and Strap Low to set the strap option to 0.

FIGURE 3-6:

LED PIN STRAP EXAMPLE

+V

LED/

R

Strap High

k

Strap Pin

HUB

Strap Pin

HUB

R

k

LED/

Strap Low

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DS00001692C-page 15

USB251xB/xBi

3.4

Buffer Type Descriptions

TABLE 3-4:

Buffer Type

BUFFER TYPE DESCRIPTIONS

Description

I

I/O

Input

Input/output

IPD

Input with internal weak pull-down resistor

Input with internal weak pull-up resistor

Input with Schmitt trigger

Output 12 mA

IPU

IS

O12

I/O12

I/OSD12

Input/output buffer with 12 mA sink and 12 mA source

Open drain with Schmitt trigger and 12 mA sink. Meets the I²C-Bus

Specification [2] requirements.

ICLKx

OCLKx

I-R

XTAL clock input

XTAL clock output

RBIAS

I/O-U

Analog input/output defined in USB specification

DS00001692C-page 16

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USB251xB/xBi

4.0

BATTERY CHARGING SUPPORT

The USB251xB/xBi hub provides support for battery charging devices on a per port basis in compliance with the USB

Battery Charging Specification, Revision 1.1. The hub can be configured to individually enable each downstream port

for battery charging support either via pin strapping as illustrated in Figure 4-1 or by setting the corresponding configu-

ration bits via I²C EEPROM or SMBus (Section 5.1 on page 19).

FIGURE 4-1:

BATTERY CHARGING VIA EXTERNAL POWER SUPPLY

3.3 V

5.0 V

USB Port Power

Controller

R_STRAP

IN

USB251xB/xBi

VBUS

PRTPWR[x:1]

OCS_N[x]

EN

FLAG

Note:

R_STRAPenables battery charging.

4.1

USB Battery Charging

A downstream port enabled for battery charging turns on port power as soon as the power on reset and hardware con-

figuration process has completed. The hub does not need to be enumerated nor does VBUS_DET need to be asserted

for the port power to be enabled. These conditions allow battery charging in S3, S4, and S5 system power states as well

as in the fully operational state. The USB Battery Charging Specification does not interfere with standard USB operation,

which allows a device to perform battery charging at any time.

A port that supports battery charging must be able to support 1.5 amps of current on VBUS. Standard USB port power

controllers typically only allow for 0.8 amps of current before detecting an over-current condition. Therefore, the 5 volt

power supply, port power controller, or over-current protection devices must be chosen to handle the larger current

demand compared to standard USB hub designs.

4.1.1

SPECIAL BEHAVIOR OF PRTPWR PINS

The USB251xB/xBi enables VBUS by asserting the port power (PRTPWR) as soon as the hardware configuration pro-

cess has completed. If the port detects an over-current condition, PRTPWR will be turned off to protect the circuitry from

overloading. If an over-current condition is detected when the hub is not enumerated, PRTPWR can only be turned on

from the host or if RESET_N is toggled. These behaviors provide battery charging even when the hub is not enumerated

and protect the hub from sustained short circuit conditions. If the short circuit condition persists when the hub is plugged

into a host system the user is notified that a port has an over-current condition. Otherwise PRTPWR turned on by the

host system and the ports operate normally.

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 17

USB251xB/xBi

4.2

Battery Charging Configuration

The battery charging option can be configured in one of two ways:

• When the hub is brought up in the default configuration with strapping options enabled, with the PRT-

PWR[x:1]/BC_EN[x:1] pins configured. See the following sections for details:

- Section 3.3, "Pin Descriptions (Grouped by Function)," on page 12

- Section 3.3.1.2, "Internal Pull-Down (IPD)," on page 15

• When the hub is initialized for configuration over I²C EEPROM or SMBus. Either of these interfaces can be used

to configure the battery charging option.

2

4.2.1

BATTERY CHARGING ENABLED VIA I C EEPROM OR SMBUS

Register memory map location 0xD0 is allocated for battery charging support. The Battery Charging register at location

0xD0 starting from bit 1 enables battery charging for each downstream port when asserted. Bit 1 represents port 1, bit

2 represents port 2, etc. Each port with battery charging enabled asserts the corresponding PRTPWR[x:1] pin.

DS00001692C-page 18

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

5.0

INITIAL INTERFACE/CONFIGURATION OPTIONS

The hub must be configured in order to correctly function when attached to a USB host controller. The hub can be con-

figured either internally or externally by setting the CFG_SEL[1:0] pins (immediately after RESET_N negation) as out-

lined in the table below.

Note:

See Chapter 11 (Hub Specification) of the USB specification for general details regarding hub operation

and functionality.

To configure the hub externally, there are two principal ways to interface to the hub: over SMBus or I²C EEPROM. The

hub can be configured internally, where several default configurations are available as described in the table below.

When configured internally, additional configuration is available using the strap options (listed in Section 3.3.1 on page

14).

Note:

Strap options are not available when configuring the hub over I²C or SMBus.

TABLE 5-1:

CFG_SEL[1]

INITIAL INTERFACE/CONFIGURATION OPTIONS

CFG_SEL[0]

Description

0

Default configuration:

• Strap options enabled

• Self-powered operation enabled

• Individual power switching

• Individual over-current sensing

0

1

The hub is configured externally over SMBus (as an SMBus slave

device):

• Strap options disabled

• All registers configured over SMBus

1

0

1

Default configuration with the following overrides:

• Bus-powered operation

The hub is configured over 2-wire I²C EEPROM:

• Strap options disabled

• All registers configured by I²C EEPROM

5.1

Internal Register Set (Common to I²C EEPROM and SMBus)

The register set available when configuring the hub to interface over I²C or SMBus is outlined in the table below. Each

register has R/W capability, where EEPROM reset values are 0x00. Reserved registers should be written to 0 unless

otherwise specified. Contents read from unavailable registers should be ignored.

Default ROM Values

(Hexidecimal)

Address

Register Name

00h

01h

02h

03h

04h

05h

Vendor ID LSB

Vendor ID MSB

Product ID LSB

Product ID MSB

Device ID LSB

Device ID MSB

24

04

13

25

B3

0B

12

14

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DS00001692C-page 19

USB251xB/xBi

Default ROM Values

(Hexidecimal)

Address

Register Name

06h

07h

Configuration Data Byte 1

Configuration Data Byte 2

Configuration Data Byte 3

Non-Removable Devices

Port Disable (Self)

Port Disable (Bus)

Max Power (Self)

Max Power (Bus)

Hub Controller Max Current (Self)

Hub Controller Max Current (Bus)

Power-on Time

9B

20

02

00

01

32

01

32

00

08h

09h

0Ah

0Bh

0Ch

0Dh

0Eh

0Fh

10h

11h

Language ID High

Language ID Low

Manufacturer String Length

Product String Length

Serial String Length

Manufacturer String

Product String

12h

13h

14h

15h

16h-53h

54h-91h

92h-CFh

D0h

Serial String

Battery Charging Enable

rsvd

E0h

F5h

rsvd

F6h

Boost_Up

F7h

rsvd

F8h

Boost_x:0

F9h

rsvd

FAh

Port Swap

FBh

FCh

FD-FEh

FFh

Port Map 12

Port Map 34

-

00

rsvd

00

Status/Command

Note: SMBus register only

DS00001692C-page 20

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

5.1.1

REGISTER 00H: VENDOR ID (LSB)

Bit Number

Bit Name

Description

7:0

VID_LSB

Least Significant Byte of the Vendor ID: a 16-bit value that uniquely identifies

the Vendor of the user device (assigned by USB-Interface Forum). Set this

field using either the SMBus or I²C EEPROM interface options.

5.1.2

REGISTER 01H: VENDOR ID (MSB)

Bit Number

Bit Name

Description

7:0

VID_MSB

Most Significant Byte of the Vendor ID: a 16-bit value that uniquely identifies

the Vendor of the user device (assigned by USB-Interface Forum). Set this field

using either the SMBus or I²C EEPROM interface options.

5.1.3

REGISTER 02H: PRODUCT ID (LSB)

Bit Number

Bit Name

Description

7:0

PID_LSB

Least Significant Byte of the Product ID: a 16-bit value that uniquely identifies

the Product ID of the user device. Set this field using either the SMBus or I²C

EEPROM interface options.

5.1.4

REGISTER 03H: PRODUCT ID (MSB)

Bit Number

Bit Name

Description

7:0

PID_MSB

Most Significant Byte of the Product ID: a 16-bit value that uniquely identifies

the Product ID of the user device. Set this field using either the SMBus or I²C

EEPROM interface options.

5.1.5

REGISTER 04H: DEVICE ID (LSB)

Bit Number

Bit Name

Description

7:0

DID_LSB

Least Significant Byte of the Device ID: a 16-bit device release number in

BCD format (assigned by OEM). Set this field using either the SMBus or I²C

EEPROM interface options.

5.1.6

REGISTER 05H: DEVICE ID (MSB)

Bit Number

Bit Name

Description

7:0

DID_MSB

Most Significant Byte of the Device ID: a 16-bit device release number in BCD

format (assigned by OEM). Set this field using either the SMBus or I²C

EEPROM interface options.

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DS00001692C-page 21

USB251xB/xBi

5.1.7

REGISTER 06H: CONFIG_BYTE_1

Bit Number

Bit Name

Description

7

SELF_BUS_PWR

Self or Bus Power: selects between self- and bus-powered operation.

The hub is either self-powered (draws less than 2 mA of upstream bus power)

or bus-powered (limited to a 100 mA maximum of upstream power prior to

being configured by the host controller).

When configured as a bus-powered device, the hub consumes less than

100 mA of current prior to being configured. After configuration, the bus-

powered hub, along with all associated hub circuitry, any embedded devices

(if part of a compound device), and all externally available downstream ports

(max 100 mA) must consume no more than 500 mA of upstream VBUS

current. The current consumption is system dependent and must not violate

the USB 2.0 Specification [1].

When configured as a self-powered device, < 1 mA of upstream VBUS current

is consumed and all ports are available. Each port is capable of sourcing

500 mA of current.

This field is set over either the SMBus or I²C EEPROM interface options.

0 : bus-powered operation

1 : self-powered operation

If dynamic power switching is enabled (Section 5.1.8), this bit is ignored and

LOCAL_PWR is used to determine if the hub is operating from self or bus

power.

6

5

rsvd

HS_DISABLE

Hi-Speed Disable: disables the capability to attach as either a hi- or full-speed

device, forcing full-speed attachment only (i.e., no hi-speed support).

0 : hi-/full-speed

1 : full-speed only (hi-speed disabled)

4

3

MTT_ENABLE

EOP_DISABLE

Multi-TT Enable: enables one transaction translator per port operation.

Selects between a mode where only one transaction translator is available for

all ports (single-TT), or each port gets a dedicated transaction translator

(multi-TT).

0 : single TT for all ports

1 : multi-TT (one TT per port)

EOP Disable: disables End Of Packet (EOP) generation at End Of Frame

Time #1 (EOF1) when in full-speed mode.

During full-speed operation only, the hub can send EOP when no downstream

traffic is detected at EOF1. See the USB 2.0 Specification, Section 11.3.1 for

details.

0 : EOP generation is normal

1 : EOP generation is disabled

2:1

CURRENT_SNS

PORT_PWR

Over-Current Sense: selects current sensing on all ports (ganged); a port-by-

port basis (individual); or none (for bus-powered hubs only). The ability to

support current sensing on a ganged or port-by-port basis is hardware

implementation dependent.

00 : ganged sensing

01 : individual sensing

1x : over-current sensing not supported (use with bus-powered configurations)

0

Port Power Switching: enables power switching on all ports (ganged) or a port-

by-port basis (individual). The ability to support power enabling on a ganged

or port-by-port basis is hardware implementation dependent.

0 : ganged switching

1 : individual switching

DS00001692C-page 22

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USB251xB/xBi

5.1.8

REGISTER 07H: CONFIGURATION DATA BYTE 2

Bit Number

Bit Name

Description

7

DYNAMIC

Dynamic Power Enable: controls the ability of the hub to automatically change

from self-powered to bus-powered operation if the local power source is

removed or unavailable. It can also go from bus-powered to self-powered

operation if the local power source is restored.

When dynamic power switching is enabled, the hub detects the availability of

a local power source by monitoring LOCAL_PWR. If the hub detects a change

in power source availability, the hub immediately disconnects and removes

power from all downstream devices. It also disconnects the upstream port.

The hub will then re-attach to the upstream port as either a bus-powered hub

(if local power is unavailable) or a self-powered hub (if local power is

available).

0 : no dynamic auto-switching

1 : dynamic auto-switching capable

6

rsvd

5:4

OC_TIMER

Over Current Timer Delay:

00 : 0.1 ms

01 : 4.0 ms

10 : 8.0 ms

11 : 16.0 ms

3

COMPOUND

Compound Device: indicates the hub is part of a compound device (see the

USB Specification for definition). The applicable port(s) must also be defined

as having a non-removable device.

Note:

When configured via strapping options, declaring a port as non-

removable automatically causes the hub controller to report that it is

part of a compound device.

0 : no

1 : yes, the hub is part of a compound device

2:0

rsvd

5.1.9

REGISTER 08H: CONFIGURATION DATA BYTE 3

Bit Number

Bit Name

Description

7:4

3

rsvd

PRTMAP_EN

Port Mapping Enable: selects the method used by the hub to assign port

numbers and disable ports.

0 : standard mode

1 : port mapping mode

2:1

0

rsvd

STRING_EN

Enables String Descriptor Support

0 : string support disabled

1 : string support enabled

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 23

USB251xB/xBi

5.1.10

REGISTER 09H: NON-REMOVABLE DEVICE

Bit Number

Bit Name

Description

7:0

NR_DEVICE

Non-Removable Device: indicates which port has a non-removable device.

0 : port is removable

1 : port is non-removable

Bit 7 : rsvd

Bit 6 : rsvd

Bit 5 : rsvd

Bit 4 : controls port 4

Bit 3 : controls port 3

Bit 2 : controls port 2

Bit 1 : controls port 1

Bit 0 : rsvd

Note:

The device must provide its own descriptor data.

When using the default configuration, the NON_REM[1:0] pins will designate

the appropriate ports as being non-removable.

5.1.11

REGISTER 0AH: PORT DISABLE FOR SELF-POWERED OPERATION

Bit Number

Bit Name

Description

7:0

PORT_DIS_SP

Port Disable Self-Powered: disables one or more ports.

0 = port is available

1 = port is disabled

Bit 7 : rsvd

Bit 6 : rsvd

Bit 5 : rsvd

Bit 4 : controls port 4

Bit 3 : controls port 3

Bit 2 : controls port 2

Bit 1 : controls port 1

Bit 0 : rsvd

During self-powered operation when mapping mode is disabled (PRTMAP_EN

= 0), this register selects the ports that will be permanently disabled. These

ports are then unavailable and cannot be enabled or enumerated by a host

controller. The ports can be disabled in any order, where the internal logic will

automatically report the correct number of enabled ports to the USB host. The

active ports will be reordered in order to ensure proper function.

When using the default configuration, PRT_DIS_P[x:1] and PRT_DIS_M[x:1]

pins disable the appropriate ports.

DS00001692C-page 24

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

5.1.12

REGISTER 0BH: PORT DISABLE FOR BUS-POWERED OPERATION

Bit Number

Bit Name

Description

7:0

PORT_DIS_BP

Port Disable Bus-Powered: disables one or more ports.

0 = port is available

1 = port is disabled

Bit 7 : rsvd

Bit 6 : rsvd

Bit 5 : rsvd

Bit 4 : controls port 4

Bit 3 : controls port 3

Bit 2 : controls port 2

Bit 1 : controls port 1

Bit 0 : rsvd

During self-powered operation when mapping mode is disabled (PRTMAP_EN

= 0), this selects the ports which will be permanently disabled.These ports are

then unavailable and cannot be enabled or enumerated by a host controller.

The ports can be disabled in any order, where the internal logic will

automatically report the correct number of enabled ports to the USB host. The

active ports will be reordered in order to ensure proper function.

When using the internal default option, the PRT_DIS_P[x:1] and

PRT_DIS_M[x:1] pins disable the appropriate ports.

5.1.13

REGISTER 0CH: MAX POWER FOR SELF-POWERED OPERATION

Bit Number

Bit Name

Description

7:0

MAX_PWR_SP

Max Power Self-Powered: the value in 2 mA increments that the hub

consumes from an upstream port (VBUS) when operating as a self-powered

hub. This value includes the hub silicon along with the combined power

consumption (from VBUS) of all associated circuitry on the board. This value

also includes the power consumption of a permanently attached peripheral if

the hub is configured as a compound device. The embedded peripheral

reports 0 mA in its descriptors.

Note:

The USB 2.0 Specification does not permit this value to exceed

100 mA

5.1.14

REGISTER 0DH: MAX POWER FOR BUS-POWERED OPERATION

Bit Number

Bit Name

Description

7:0

MAX_PWR_BP

Max Power Bus-Powered: the value in 2 mA increments that the hub

consumes from an upstream port (VBUS) when operating as a bus-powered

hub. This value includes the hub silicon along with the combined power

consumption (from VBUS) of all associated circuitry on the board. This value

also includes the power consumption of a permanently attached peripheral if

the hub is configured as a compound device. The embedded peripheral

reports 0 mA in its descriptors.

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 25

USB251xB/xBi

5.1.15

REGISTER 0EH: HUB CONTROLLER MAX CURRENT FOR SELF-POWERED OPERATION

Bit Number

Bit Name

Description

7:0

HC_MAX_C_SP

Hub Controller Max Current Self-Powered: the value in 2 mA increments that

the hub consumes from an upstream port (VBUS) when operating as a self-

powered hub. This value includes the hub silicon along with the combined

power consumption (from VBUS) of all associated circuitry on the board. This

value does NOT include the power consumption of a permanently attached

peripheral if the hub is configured as a compound device.

Note:

The USB 2.0 Specification does not permit this value to exceed

100 mA

A value of 50 (decimal) indicates 100 mA, which is the default value.

5.1.16

REGISTER 0FH: HUB CONTROLLER MAX CURRENT FOR BUS-POWERED OPERATION

Bit Number

Bit Name

Description

7:0

HC_MAX_C_BP

Hub Controller Max Current Bus-Powered: the value in 2 mA increments that

the hub consumes from an upstream port (VBUS) when operating as a bus-

powered hub. This value will include the hub silicon along with the combined

power consumption (from VBUS) of all associated circuitry on the board.

Note:

This value will not include the power consumption of a permanently

attached peripheral if the hub is configured as a compound device.

A value of 50 (decimal) would indicate 100 mA, which is the default value.

5.1.17

REGISTER 10H: POWER-ON TIME

Bit Number

Bit Name

Description

7:0

POWER_ON_TIME Power-On Time: the length of time that it takes (in 2 ms intervals) from the

time the host initiated the power-on sequence on a port until the port has

adequate power.

5.1.18

REGISTER 11H: LANGUAGE ID HIGH

Bit Number

Bit Name

Description

7:0

LANG_ID_H

USB Language ID: upper 8 bits of a 16-bit ID field

5.1.19

REGISTER 12H: LANGUAGE ID LOW

Bit Number

Bit Name

Description

7:0

LANG_ID_L

USB Language ID: lower 8 bits of a 16-bit ID field

5.1.20

REGISTER 13H: MANUFACTURER STRING LENGTH

Bit Number

Bit Name

Description

7:0

MFR_STR_LEN

Manufacturer String Length: with a maximum string length of 31 characters

(when supported).

DS00001692C-page 26

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

5.1.21

REGISTER 14H: PRODUCT STRING LENGTH

Bit Number

Bit Name

Description

7:0

PRD_STR_LEN

Product String Length: with a maximum string length of 31 characters (when

supported).

5.1.22

REGISTER 15H: SERIAL STRING LENGTH

Bit Number

Bit Name

Description

7:0

SER_STR_LEN

Serial String Length: with a maximum string length of 31 characters (when

supported).

5.1.23

REGISTER 16H-53H: MANUFACTURER STRING

Bit Number

Bit Name

Description

7:0

MFR_STR

Manufacturer String: UNICODE UTF-16LE per USB 2.0 Specification: with a

maximum string length of 31 characters (when supported).

Note:

The string consists of individual 16-bit UNICODE UTF-16LE

characters. The characters will be stored starting with the LSB at the

least significant address and the MSB at the next 8-bit location.

(Subsequent characters must be stored in sequential contiguous

addresses in the same LSB, MSB manner.)

Warning: Close attention to the byte order of the selected programming tool

should be monitored.

5.1.24

REGISTER 54H-91H: PRODUCT STRING

Bit Number

Bit Name

Description

7:0

PRD_STR

Product String: UNICODE UTF-16LE per USB 2.0 Specification

When supported, the maximum string length is 31 characters (62 bytes).

Note:

The string consists of individual 16-bit UNICODE UTF-16LE

characters. The characters will be stored starting with the LSB at the

least significant address and the MSB at the next 8-bit location.

(Subsequent characters must be stored in sequential contiguous

address in the same LSB, MSB manner.)

Warning: Close attention to the byte order of the selected programming tool

should be monitored.

5.1.25

REGISTER 92H-CFH: SERIAL STRING

Bit Number

Bit Name

Description

7:0

SER_STR

Serial String: UNICODE UTF-16LE per USB 2.0 specification

When supported, the maximum string length is 31 characters (62 bytes).

Note:

The string consists of individual 16-bit UNICODE UTF-16LE

characters. The characters will be stored starting with the LSB at the

least significant address and the MSB at the next 8-bit location.

(Subsequent characters must be stored in sequential contiguous

address in the same LSB, MSB manner.)

Warning: Close attention to the byte order of the selected programming tool

should be monitored.

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 27

USB251xB/xBi

5.1.26

REGISTER D0H: BATTERY CHARGING ENABLE

Bit Number

Bit Name

Description

7:0

BC_EN

Battery Charging Enable: enables the battery charging feature for the

corresponding port.

0 : battery charging support is not enabled

1 : battery charging support is enabled

Bit 7 : rsvd

Bit 6 : rsvd

Bit 5 : rsvd

Bit 4 : controls port 4

Bit 3 : controls port 3

Bit 2 : controls port 2

Bit 1 : controls port 1

Bit 0 : rsvd

5.1.27

REGISTER F6H: BOOST_UP

Bit Number

Bit Name

Description

7:2

1:0

rsvd

BOOST_IOUT

USB electrical signaling drive strength boost bit for the upstream port.

00 : normal electrical drive strength - no boost

01 : elevated electrical drive strength - low (~ 4% boost)

10 : elevated electrical drive strength - medium (~ 8% boost)

11 : elevated electrical drive strength - high (~12% boost)

Note:

Boost could result in non-USB compliant parameters. Therefore, a

value of 00 should be implemented unless specific implementation

issues require additional signal boosting to correct for degraded USB

signalling levels.

DS00001692C-page 28

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USB251xB/xBi

5.1.28

REGISTER F8H: BOOST_4:0

Bit Number

Bit Name

Description

7:6

BOOST_IOUT_4

USB electrical signaling drive strength boost bit for downstream port 4.

00 : normal electrical drive strength - no boost

01 : elevated electrical drive strength - low (~4% boost)

10 : elevated electrical drive strength - medium (~ 8% boost)

11 : elevated electrical drive strength - high (~12% boost)

5:4

3:2

1:0

BOOST_IOUT_3

BOOST_IOUT_2

BOOST_IOUT_1

USB electrical signaling drive strength boost bit for downstream port 3.

00 : normal electrical drive strength - no boost

01 : elevated electrical drive strength - low (~4% boost)

10 : elevated electrical drive strength - medium (~ 8% boost)

11 : elevated electrical drive strength - high (~12% boost)

USB electrical signaling drive strength boost bit for downstream port 2.

00 : normal electrical drive strength - no boost

01 : elevated electrical drive strength - low (~4% boost)

10 : elevated electrical drive strength - medium (~ 8% boost)

11 : elevated electrical drive strength - high (~12% boost)

USB electrical signaling drive strength boost bit for downstream port 1.

00 : normal electrical drive strength - no boost

01 : elevated electrical drive strength - low (~4% boost)

10 : elevated electrical drive strength - medium (~ 8% boost)

11 : elevated electrical drive strength - high (~12% boost)

Note:

Boost could result in non-USB compliant parameters. Therefore, a value of 00 should be implemented

unless specific implementation issues require additional signal boosting to correct for degraded USB sig-

naling levels.

5.1.29

REGISTER FAH: PORT SWAP

Bit Number

Bit Name

Description

7:0

PRTSP

Port Swap: swaps the upstream USBDP/USBDM pins (USBDP_UP and

USBDM_UP) and the downstream USBDP/USBDM pins (USBDP_DN[x:1] and

USBDP_DN[x:1]) for ease of board routing to devices and connectors.

0 : USB D+ functionality is associated with the DP pin and D- functionality is

associated with the DM pin.

1 : USB D+ functionality is associated with the DM pin and D- functionality is

associated with the DP pin.

Bit 7 : rsvd

Bit 6 : rsvd

Bit 5 : rsvd

Bit 4 : controls port 4

Bit 3 : controls port 3

Bit 2 : controls port 2

Bit 1 : controls port 1

Bit 0 : when set to 1, the upstream port DP/DM is swapped.

 2010 - 2015 Microchip Technology Inc.

DS00001692C-page 29

USB251xB/xBi

5.1.30

REGISTER FBH: PORTMAP 12

Bit Number

Bit Name

Description

7:0

PRTR12

PortMap Register for Ports 1 and 2: When a hub is enumerated by a USB

host controller, the hub is only permitted to report how many ports it has; the

hub is not permitted to select a numerical range or assignment. The host

controller will number the downstream ports of the hub starting with the

number 1, up to the number of ports that the hub reports having.

The host's port number is called the Logical Port Number and the physical

port on the hub is the Physical Port Number. When mapping mode is enabled

(see PRTMAP_EN, Section 5.1.9 on page 23) the hub's downstream port

numbers can be mapped to different logical port numbers (assigned by the

host).

Note:

Contiguous logical port numbers must be implemented, starting from

number 1 up to the maximum number of enabled ports. This ensures

that the hub's ports are numbered in accordance with the way a host

will communicate with the ports.

Bit [7:4]

0000

0001

0010

0011

0100

Physical port 2 is disabled

Physical port 2 is mapped to logical port 1

Physical port 2 is mapped to logical port 2

Physical port 2 is mapped to logical port 3

Physical port 2 is mapped to logical port 4

rsvd, will default to 0000 value

1000

to

1111

Bit [3:0]

0000

0001

0010

0011

0100

Physical port 1 is disabled

Physical port 1 is mapped to logical port 1

Physical port 1 is mapped to logical port 2

Physical port 1 is mapped to logical port 3

Physical port 1 is mapped to logical port 4

rsvd, will default to 0000 value

1000

to

1111

DS00001692C-page 30

 2010 - 2015 Microchip Technology Inc.

USB251xB/xBi

5.1.31

REGISTER FCH: PORTMAP 34

Bit Number

Bit Name

Description

7:0

PRTR34

PortMap Register for Ports 3 and 4: When a hub is enumerated by a USB