USB 2.0 High-Speed 4-Port Hub Controller

Datasheet

4.3.1.27Register F8h: Boost_4:0

BIT

 

 

 

NUMBER

BIT NAME

 

DESCRIPTION

 

 

 

7:6

BOOST_IOUT_4

Upstream 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

Upstream 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

Upstream 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.

 

 

 

1:0

BOOST_IOUT_1

Upstream USB electrical signaling drive strength Boost Bit for Downstream

 

 

Port ‘1’.

 

 

 

‘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.

 

 

 

 

Revision 1.98 (11-19-07)

30

SMSC USB2514

 

DATASHEET