2-Port USB 2.0 Hi-Speed Hub Controller

Datasheet

SMSC USB2412

15

Revision 1.3 (12-27-11)

DATASHEET

3.2.1.1

RESET_N

Figure 3.1 Reset_N Timing

Note: All power supplies must have reached the operating levels mandated in Chapter 4, DC

Parameters, prior to (or coincident with) the assertion of RESET_N.

3.2.2

USB Bus Reset

In response to the upstream port signaling a reset to the hub, the hub does the following:

1. Sets default address to 0.

2. Sets configuration to unconfigured.

3. Negates PRTPWR[2:1] to all downstream ports.

4. Clears all TT buffers.

5. Moves device from suspended to active (if suspended).

6. Complies with Section 11.10 of the USB 2.0 Specification for behavior after completion of the reset

sequence. The host then configures the hub and the hub’s downstream port devices in accordance

with the specification.

Note: The hub does not propagate the upstream USB reset to downstream devices.

Table 3.1 Reset_N Timing

NAME

DESCRIPTION

MIN

TYP

MAX

UNITS

t1

RESET_N asserted

1

μsec

t2

Strap setup time

16.7

nsec

t3

Strap hold time

16.7

1400

nsec

t4

Hub outputs driven to inactive logic states

1.5

2

μsec

t5

USB attach (See Note)

100

msec

t6

Host acknowledges attach and signals USB reset

100

msec

t7

USB idle

undefined

msec

t8

Completion time for requests (with or without data

stage)

5

msec

t1

t4

t5

t6

t7

t8

Valid

Driven by Hub if strap is an output

RESET_N

VSS

NON_REM[1:0]

VSS

Hardware

reset asserted

Read

NON_REM[1:0]

p

Outputs to

inactive levels

USB

Upstream

USB Reset

recovery

Idle

Start completion

request response

t2

t3

Don’t Care

Don’t Care