SMSC USB4640i ユーザーズマニュアル

High Speed Inter-Chip USB 2.0 Hub and Flash Media Controller

SMSC USB4640/USB4640i

53

Revision 1.0 (06-01-09)

6. The PLL is halted.

Note: All power supplies must have reached the operating levels mandated in 

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

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

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

1. Sets default address to ‘0’.

2. Sets configuration to: Unconfigured.

3. Negates PRTCTL[3:2] 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 device and the device’s downstream port devices in accordance with the
USB 2.0 Specification.

t1

nRESET asserted

1

μsec

t2

Device recovery/stabilization

500

μsec

t3

8051 programs device configuration

20

50

msec

t4

USB attach (See Note)

100

msec

t5

Host acknowledges attach and signals USB reset

100

msec

t6

USB idle

Undefined

msec

t7

Completion time for requests (with or without data 

stage)

5

msec

t1

t2

t4

t5

t6

t7

nRESET

VSS

Hardware 

reset 

asserted

Device 

Recovery/

Stabilization

8051 Sets 

Configuration 

Registers

Attach 

USB 

Upstream

USB Reset 

recovery

Idle

Start 

completion 

request 

response

t3