USB2422SLASHMJ datasheet(29/51 Pages) SMSC

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2-Port USB 2.0 Hi-Speed Hub Controller

Datasheet

SMSC USB2422

Revision 1.0 (06-04-13)

DATASHEET

4.4.8

Configuration Data Byte 2 Register (CFG2)

Address:

07h

Size:

8 bits

BITS

DESCRIPTION

TYPE

DEFAULT

Dynamic Power Enable (DYNAMIC)

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).

Note:

If the local power source is available, the Hub will always switch to

Self-Powered operation.

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

(pin becomes SUSP_IND) and the hub controller will utilize the inverse of

the SELF_BUS_PWR bit for 'Hub_Status_Field' bit '0' (local power source)

1 = Dynamic Auto-switching capable

(pin becomes LOCAL_PWR) and the hub controller will utilize the

LOCAL_PWR pin for 'Hub_Status_Field' bit '0' (local power source)

R/W

RESERVED

5:4

Over Current Timer Delay (OC_TIMER)

00 = 0.1ms

01 = 4ms

10 = 8ms

11 = 16ms

R/W

00b

Compound Device (COMPOUND)

Allows the 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, Hub is part of a compound device

R/W

2:0

RESERVED

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