Datasheet
High-Speed Inter-Chip (HSIC) USB 2.0 Hub and Flash Media Controller
Datasheet
Revision 1.3 (03-13-13) 42 SMSC USB4640/USB4640i
DATASHEET
4.4.4.18 EFh: Boost_Up
4.4.4.19 F0h: Boost_3:0
BIT NAME DESCRIPTION
7:2 rsvd
1:0 BOOST_IOUT USB electrical signaling drive strength boost bit for the upstream port A.
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. Therefore, a
value of
00 should be implemented unless specific implementation
issues require additional signal boosting to correct for degraded
USB signalling levels.
BIT NAME DESCRIPTION
7:6 rsvd
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)
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. Therefore, a
value of
00 should be implemented unless specific implementation
issues require additional signal boosting to correct for degraded
USB signalling levels.
1:0 rsvd Always read as 0