USB2512AI datasheet(31/63 Pages) MICROCHIP

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USB 2.0 Hi-Speed Hub Controller

Datasheet

SMSC USB251xB/xBi

Revision 2.2 (02-17-12)

DATASHEET

5.1.8

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

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

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

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

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