USB MultiSwitchTM Hub

Datasheet

9.1.1.3RESET_N for SMBus Slave Configuration

Hardware

 

 

 

Attach

 

 

Start

Reset

SMBus Code

Hub PHY

USB Reset

 

completion

reset

USB

Idle

Negation

Load

Stabilization

recovery

request

asserted

Upstream

 

 

 

 

 

 

response

 

 

 

 

 

 

 

t1 t2 t3 t4 t5 t6 t7

RESET_N

VSS

Figure 9.3 Reset_N Timing for SMBus Mode

Table 9.3 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 9.3)

 

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).

 

 

 

 

 

 

 

 

 

 

Note: For Bus-Powered configurations, the Hub and its associated circuitry will consume more than 100mA from the upstream USB power source during t2+t3+t4+t5+t6+t7.

Note 9.3 For Self-Powered configurations, t3 MAX is not applicable and the time to load the configuration is determined by the external SMBus host.

9.1.2USB 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.

„Sets default address to 0.

„Sets configuration to: Unconfigured.

„Negates PRTPWR[4:1] to all downstream ports.

„Clears all TT buffers.

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

Revision 1.91 (08-22-07)

50

SMSC USB2524

 

DATASHEET