Datasheet

USB 2.0 Hi-Speed 7-Port Hub Controller
Datasheet
Revision 2.8 (09-17-12) 30 SMSC USB2517
DATASHEET
7.2.1.28 Register F8h: Boost_4:0
7:6 Reserved Reserved
5:4 BOOST_IOUT_7 USB electrical signaling drive strength Boost Bit for Downstream Port ‘7’.
‘00’ = Normal electrical drive strength
‘01’ = Elevated electrical drive strength (+4% boost)
‘10’ = Elevated electrical drive strength (+8% boost)
‘11’ = Elevated electrical drive strength (+12% boost)
3:2 BOOST_IOUT_6 USB electrical signaling drive strength Boost Bit for Downstream Port ‘6’.
‘00’ = Normal electrical drive strength
‘01’ = Elevated electrical drive strength (+4% boost)
‘10’ = Elevated electrical drive strength (+8% boost)
‘11’ = Elevated electrical drive strength (+12% boost)
1:0 BOOST_IOUT_5 USB electrical signaling drive strength Boost Bit for Downstream Port ‘5’.
‘00’ = Normal electrical drive strength
‘01’ = Elevated electrical drive strength (+4% boost)
‘10’ = Elevated electrical drive strength (+8% boost)
‘11’ = Elevated electrical drive strength (+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 (approximately 4% boost)
‘10’ = Elevated electrical drive strength = Medium (approximately 8% boost)
‘11’ = Elevated electrical drive strength = High (approximately 12% boost)
Note: “Boost” could result in non-USB Compliant parameters (one
example would be Test J/K levels), the OEM should use a ‘00’
value unless specific implementation issues require additional
signal boosting to correct for degraded USB signalling levels.
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 (approximately 4% boost)
‘10’ = Elevated electrical drive strength = Medium (approximately 8% boost)
‘11’ = Elevated electrical drive strength = High (approximately 12% boost)
Note: “Boost” could result in non-USB Compliant parameters (one
example would be Test J/K levels), the OEM should use a ‘00’
value unless specific implementation issues require additional
signal boosting to correct for degraded USB signalling levels.
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 (approximately 4% boost)
‘10’ = Elevated electrical drive strength = Medium (approximately 8% boost)
‘11’ = Elevated electrical drive strength = High (approximately 12% boost)
Note: “Boost” could result in non-USB Compliant parameters (one
example would be Test J/K levels), the OEM should use a ‘00’
value unless specific implementation issues require additional
signal boosting to correct for degraded USB signalling levels.