Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB251xB/xBi 37 Revision 2.2 (02-17-12)
DATASHEET
5.1.25 Register 92h-CFh: Serial String
5.1.26 Register D0h: Battery Charging Enable
5.1.27 Register F6h: Boost_Up
BIT
NUMBER BIT NAME DESCRIPTION
7:0 SER_STR Serial String: UNICODE UTF-16LE per USB 2.0 specification
When supported, the maximum string length is 31 characters (62 bytes).
Note: The string consists of individual 16-bit UNICODE UTF-16LE
characters. The characters will be stored starting with the LSB at
the least significant address and the MSB at the next 8-bit location.
(Subsequent characters must be stored in sequential contiguous
address in the same LSB, MSB manner.)
Warning: Close attention to the byte order of the selected programming
tool should be monitored.
BIT
NUMBER BIT NAME DESCRIPTION
7:0 BC_EN Battery Charging Enable: enables the battery charging feature for the
corresponding port.
0 : battery charging support is not enabled
1 : battery charging support is enabled
Bit 7 : rsvd
Bit 6 : rsvd
Bit 5 : rsvd
Bit 4 : controls port 4
Bit 3 : controls port 3
Bit 2 : controls port 2
Bit 1 : controls port 1
Bit 0 : rsvd
BIT
NUMBER BIT NAME DESCRIPTION
7:2 rsvd
1:0 BOOST_IOUT USB electrical signaling drive strength boost bit for the upstream port.
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)
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.