Datasheet
Table Of Contents
- Chapter 1 USB251x Hub Family Differences Overview
- Chapter 2 General Description
- Chapter 3 Acronyms
- Chapter 4 Block Diagram
- Chapter 5 Pin Descriptions
- Chapter 6 LED Usage Description
- Chapter 7 Battery Charging Support
- Chapter 8 Configuration Options
- Chapter 9 DC Parameters
- 9.1 Maximum Guaranteed Ratings
- 9.2 Operating Conditions
- Figure 9.1 Supply Rise Time Model
- Table 9.1 DC Electrical Characteristics (continued)
- Table 9.2 Supply Current Unconfigured: Hi-Speed Host (ICCINTHS)
- Table 9.3 Supply Current Unconfigured: Full-Speed Host (ICCINTFS)
- Table 9.4 Supply Current Configured: Hi-Speed Host (IHCH1)
- Table 9.5 Supply Current Configured: Full-Speed Host (IFCC1)
- Table 9.6 USB251x/xi/xA/xAi Supply Current Suspend (ICSBY)
- Table 9.7 USB251xB/xBi Supply Current Suspend (ICSBY)
- Table 9.8 USB251x/xi/xA/xAi Supply Current Reset (ICRST)
- Table 9.9 USB251xB/xBi Supply Current Reset (ICRST)
- Table 9.10 Pin Capacitance for USB251x, USB251xi, USB251xA, USB251xAi
- Table 9.11 Pin Capacitance for USB251xB and USB251xBi
- 9.2.1 Package Thermal Specifications
- Chapter 10 AC Specifications
- Chapter 11 Package Outlines

USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.1 (04-26-10) 40 SMSC USB251x
DATASHEET
8.2.1.9 Register 08h: Configuration Data Byte 3
8.2.1.10 Register 09h: Non-Removable Device
BIT
NUMBER BIT NAME DESCRIPTION
7:4 Reserved Reserved
3 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 LED_MODE LED Mode Selection: The LED_A[x:1]_N and LED_B[x:1]_N pins support
several different modes of operation (depending upon OEM implementation
of the LED circuit).
‘00' = USB Mode
‘01’ = Speed Indication Mode
‘10’ = Same as ‘00’, USB Mode
‘11’ = Same as ‘00’, USB Mode
Warning: Do not enable an LED mode that requires LED pins that are not
available in the specific package being used in the implementation.
Note: The hub will only report that it supports LED's to the host when
USB mode is selected. All other modes will be reported as No LED
Support.
0 STRING_EN Enables String Descriptor Support
‘0’ = String support disabled
‘1’ = String support enabled
BIT
NUMBER BIT NAME DESCRIPTION
7:0 NR_DEVICE Non-removable Device: Indicates which port(s) include non-removable
devices.
‘0’ = port is removable
‘1’ = port is non-removable
Informs the host if one of the active ports has a permanent device that is
undetachable from the hub. (Note: The device must provide its own
descriptor data.)
When using the internal default option, the NON_REM[1:0] pins will
designate the appropriate ports as being non- removable.
Bit 7= Controls Port 7
Bit 6= Controls Port 6
Bit 5= Controls Port 5
Bit 4= Controls Port 4
Bit 3= Controls Port 3
Bit 2= Controls Port 2
Bit 1= Controls Port 1
Bit 0= Reserved