USB2640 datasheet(28/60 Pages) MICROCHIP

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USB2640/USB2641

DS00001947C-page 28

 2015-2021 Microchip Technology Inc.

7.3.3.14

5Eh: USB Product String Descriptor Length

7.3.3.15

5Fh: USB Product String Descriptor Type

7.3.3.16

60h-99h: USB Product String

Note 7-4

While the full strings are reported during USB enumeration, Windows XP/Vista reads concatenated

version of the strings from the standard SCSI inquiry response when storing the values for display in

the Windows registry and device manager.

7.3.3.17

9Ah: USB BmAttribute (1 byte)

7.3.3.18

9Bh: USB MaxPower (1 byte)

Byte

Name

Description

USB_PRD_STR

USB serial 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).

Byte

Name

Description

USB_PRD_STR

USB serial 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 28 characters. (See Note 7-4)

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 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 Microchip hub consumes less

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

powered Microchip hub (along with all associated hub 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 upstream VBUS

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 upstream VBUS 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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