Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
SMSC USB251xB/xBi 29 Revision 2.3 (06-11-13)
DATASHEET
5.1.8 Register 07h: Configuration Data Byte 2
0 PORT_PWR Port Power Switching: enables power switching on all ports (ganged) or a
port-by-port basis (individual). The ability to support power enabling on a
ganged or port-by-port basis is hardware implementation dependent.
0 : ganged switching
1 : individual switching
BIT
NUMBER BIT NAME DESCRIPTION
7 DYNAMIC Dynamic Power Enable: controls the ability of the hub to automatically
change from self-powered to bus-powered operation if the local power
source is removed or unavailable. It can also go from bus-powered to self-
powered operation if the local power source is restored.
When dynamic power switching is enabled, the hub detects the availability
of a local power source by monitoring LOCAL_PWR. If the hub detects a
change in power source availability, the hub immediately disconnects and
removes power from all downstream devices. It also disconnects the
upstream port. The hub will then re-attach to the upstream port as either a
bus-powered hub (if local power is unavailable) or a self-powered hub (if
local power is available).
0 : no dynamic auto-switching
1 : dynamic auto-switching capable
6 rsvd
5:4 OC_TIMER Over Current Timer Delay:
00 : 0.1 ms
01 : 4.0 ms
10 : 8.0 ms
11 : 16.0 ms
3 COMPOUND Compound Device: indicates the hub is part of a compound device (see the
USB Specification for definition). The applicable port(s) must also be defined
as having a non-removable device.
Note: When configured via strapping options, declaring a port as non-
removable automatically causes the hub controller to report that it
is part of a compound device.
0 : no
1 : yes, the hub is part of a compound device
2:0 rsvd
BIT
NUMBER BIT NAME DESCRIPTION