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) 46 SMSC USB251x
DATASHEET
Note: “Boost” could result in non-USB Compliant parameters, OEM should use a ‘00’ value unless
specific implementation issues require additional signal boosting to correct for degraded USB
signalling levels.
8.2.1.29 Register F8h: Boost_4:0
Note: “Boost” could result in non-USB Compliant parameters, OEM should use a ‘00’ value unless
specific implementation issues require additional signal boosting to correct for degraded USB
signalling levels.
1:0 BOOST_IOUT_5 USB electrical signaling drive strength Boost Bit for Downstream Port ‘5’.
‘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)
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 BOOST_IOUT_3 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)
3:2 BOOST_IOUT_2 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)
1:0 BOOST_IOUT_1 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)
BIT
NUMBER BIT NAME DESCRIPTION