USB2251 datasheet(25/43 Pages) MICROCHIP

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 2009 - 2015 Microchip Technology Inc.

DS00002005A-page 25

USB2250/50i/51/51i

7.2.3.13

32h-5Dh: Reserved

7.2.3.14

5Eh: USB Product String Descriptor Length

7.2.3.15

5Fh: USB Product String Descriptor Type

7.2.3.16

60h-99h: USB Product String Option

7.2.3.17

9Ah: USB BmAttribute (1 byte)

7.2.3.18

9Bh: USB MaxPower (1 byte)

Byte

Name

Description

59:16

Reserved

Reserved.

Byte

Name

Description

USB_PRD_STR

_LEN

USB product string descriptor length as defined by Section 9.6.7 “String” of the

USB 2.0 Specification (Revision 2.0, 2000). This field is the “bLength” which

describes the size of the string descriptor (in bytes). Maximum string length is

29 characters

Byte

Name

Description

USB_PRD_STR

_TYP

USB product string descriptor type as defined by Section 9.6.7 “String” of the

USB 2.0 Specification (Revision 2.0, 2000). This field is the “bDescriptorType”

which is a constant value associated with a string descriptor type.

Byte

Name

Description

59:2

USB_PRD_STR

This string will be used during the USB enumeration process in the Windows®

operating system. Maximum string length is 29 characters.

Byte

Name

Description

7:0

USB_BM_ATT

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

The hub is either self-powered (draws less than 2 mA) or bus-powered (limited

to 100 mA maximum power prior to being configured by the host controller).

When configured as a bus-powered device, the Microchip device consumes

less than 100 mA of current prior to being configured. After configuration, the

bus-powered Microchip device (along with all associated device circuitry, any

embedded devices if part of a compound device, and 100 mA per externally

available downstream port) must consume no more than 500 mA of current.

The current consumption is system dependent, and the OEM must ensure that

the USB 2.0 Specification is not violated.

When configured as a self-powered device, <1 mA of current is consumed and

all ports are available, with each port being capable of sourcing 500 mA of

current.

80 = Bus-powered operation (default)

C0 = Self-powered operation

A0 = Bus-powered operation with remote wake-up

E0 = Self-powered operation with remote wake-up

Byte

Name

Description

7:0

USB_MAX_PWR

USB Max Power per the USB 2.0 Specification. Do NOT set this value greater

than 100 mA.

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