USB 2.0 Hi-Speed Hub Controller

Datasheet

8.6.1.3RESET_N for SMBus Slave Configuration

Hardware

Reset

SMBus Code

Hub PHY

Attach

USB Reset

 

Start

 

completion

reset

USB

Idle

Negation

Load

Stabilization

recovery

request

asserted

Upstream

 

 

 

 

 

 

 

 

response

 

t1

t2

t3

t4

t5

t6

 

t7

RESET_N

 

 

 

 

 

 

 

 

VSS

 

 

 

 

 

 

 

 

 

 

Figure 8.5 Reset_N Timing for SMBus Mode

 

 

 

 

Table 8.9 Reset_N Timing for SMBus Mode

 

 

NAME

 

DESCRIPTION

 

 

MIN

TYP

MAX

UNITS

t1

RESET_N Asserted.

 

 

1

 

 

μsec

t2

Hub Recovery/Stabilization.

 

 

 

 

500

μsec

t3

SMBus Code Load (See Note).

 

 

 

250

300

msec

t4

Hub Configuration and USB Attach.

 

 

 

 

100

msec

t5

Host acknowledges attach and signals USB

 

100

 

 

msec

 

Reset.

 

 

 

 

 

 

 

t6

USB Idle.

 

 

 

Undefined

 

msec

t7

Completion time for requests (with or without data

 

 

 

5

msec

 

stage).

 

 

 

 

 

 

 

Notes:

„For bus-powered configurations, the 99.5 ms (MAX) is required, and the hub and its associated circuitry must not consume more than 100 mA from the upstream USB power source during t2+t3+t4+t5+t6+t7. For Self-Powered configurations, t3 MAX is not applicable and the time to load the configuration is determined by the external SMBus host.

„All power supplies must have reached the operating levels mandated in Chapter 9, DC Parameters, prior to (or coincident with) the assertion of RESET_N.

8.6.2USB Bus Reset

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

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

1.Sets default address to 0.

2.Sets configuration to: Unconfigured.

3.Negates PRTPWR[x:1] to all downstream ports unless battery charging (BC_EN) is enabled.

4.Clears all TT buffers.

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

Revision 1.0 (3-11-09)

58

SMSC USB251x

DATASHEET