USB 2.0 Hi-Speed Hub Controller

Datasheet

BIT

 

 

NUMBER

BIT NAME

DESCRIPTION

 

 

 

2:1

CURRENT_SNS

Over-Current Sense: Selects current sensing on a port-by-port basis, all

 

 

ports ganged, or none (only for bus-powered hubs). The ability to support

 

 

current sensing on a port or ganged basis is hardware implementation

 

 

dependent.

 

 

‘00’ = Ganged sensing (all ports together)

 

 

‘01’ = Individual (port-by-port)

 

 

‘1x’ = Over-current sensing not supported (must only be used with bus-

 

 

powered configurations!)

 

 

 

0

PORT_PWR

Port Power Switching: Enables power switching on all ports simultaneously

 

 

(ganged), or port power is individually switched on and off on a port- by-port

 

 

basis (individual). The ability to support power enabling on a port or ganged

 

 

basis is hardware implementation dependent.

 

 

‘0’ = Ganged switching (all ports together)

 

 

‘1’ = Individual port-by-port switching

 

 

 

8.2.1.8Register 07h: Configuration Data Byte 2

BIT

 

 

NUMBER

BIT NAME

DESCRIPTION

 

 

 

7

DYNAMIC

Dynamic Power Enable: Controls the ability of the hub to automatically

 

 

change from self-powered operation to bus-powered operation if the local

 

 

power source is removed or is unavailable (and from bus-powered to self-

 

 

powered 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 the external LOCAL_PWR pin. If the

 

 

hub detects a change in power source availability, the hub immediately

 

 

disconnects and removes power from all downstream devices and

 

 

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

Reserved

Reserved

 

 

 

5:4

OC_TIMER

OverCurrent 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: Allows OEM to indicate that the hub is part of a

 

 

compound (see the USB specification for definition) device. 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

Reserved

Reserved

 

 

 

SMSC USB251x

39

Revision 1.0 (3-11-09)

DATASHEET