USB3500 datasheet(44/46 Pages) SMSC

44 / 46 page

Hi-Speed USB Host, Device or OTG PHY With UTMI+ Interface

Datasheet

Revision 1.0 (04-04-05)

SMSC USB3500

DATASHEET

Note: Note: Should a device attached to the host be a LS device, then the 1.5 K ohm pull-up is

applied to DM. The following discussion does not apply to a LS device attached.

At T2, the Host has detected the FS device attached to the USB bus. At this time the Host will reset

the bus by driving a SE0. The SE0 is created by switching to HS Mode and activating the HS

termination by de-asserting Termselect. The 45 ohm high speed terminations pull the bus to SE0.

At T3, the Device will respond to the SE0 by driving a “Device Chirp K” onto the bus. The “Device

Chirp K” is driven with Opmode = 10b so that bitstuffing and NRZI encoding is disabled.

During T3 the HS host will see the “Device Chirp K” and prepare to respond to the device by setting

Opmode = 10b to disable the bitstuffing and NRZI encoding.

At T4, the Device will stop driving a the Chirp K, letting the bus return to SE0, and wait for the Host

to respond. The device removes the K by de-asserting Txvalid. The device will have driven the K for

a minimum of 1mS. The Host sees the linestate change from K to SE0.

At T5, the host begins transmitting K-J pairs to the device. Each K or J is 40-60uS long and the K-J

pairs are repeated for the remainder of the 10mS USB reset.

At T6, the device has detected 3 K-J pairs. The device switches the Termselect low and changes

Opmode to 00b. The device is now in high speed and waits for the first SOF packet from the upstream

host. When Termselect is de-asserted, the HS termination is activated which lowers the amplitude of

the K-J pairs.

At T7, the host ends the K-J pairs and switches to normal HS mode by changing Opmode to 00b.

At T8, the Host sends the first SOF packet. This is done by putting the SOF PID 0xA5 on the data

bus and asserting Txvalid. The link transfers the SOF packet. After, the SOF packet a normal high

speed USB session started.

USB3500 Datasheet(PDF) 44 Page - SMSC Corporation