USB3500 datasheet(31/46 Pages) SMSC

31 / 46 page

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

Datasheet

SMSC USB3500

Revision 1.0 (04-04-05)

DATASHEET

Chapter 7 Application Notes

The following sections consist of select functional explanations to aid in implementing the USB3500

into a system. For complete description and specifications consult the USB2.0 Transceiver Macrocell

Interface Specification and Universal Serial Bus Specification Revision 2.0.

7.1

Linestate

The voltage thresholds that the LINESTATE[1:0] signals use to reflect the state of DP and DM depend

on the state of XCVRSELECT. LINESTATE[1:0] uses HS thresholds when the HS transceiver is

enabled (XCVRSELECT = 0) and FS thresholds when the FS transceiver is enabled (XCVRSELECT

= 1). There is not a concept of variable single-ended thresholds in the USB2.0 specification for HS

mode.

The HS receiver is used to detect Chirp J or K, where the output of the HS receiver is always qualified

with the Squelch signal. If squelched, the output of the HS receiver is ignored. In the USB3500, as an

alternative to using variable thresholds for the single-ended receivers, the following approach is used.

In HS device mode, 3ms of no USB activity (IDLE state) signals a reset. The Link monitors

LINESTATE[1:0] for the IDLE state. To minimize transitions on LINESTATE[1:0] while in HS mode, the

presence of !Squelch is used to force LINESTATE[1:0] to a J state.

Table 7.1 Device Linestate States (DPPD & DMPD = 0)

STATE OF DP/DM LINES

LINESTATE[1:0]

FULL SPEED

XCVRSELECT[1:0]=01

TERMSELECT=1

HIGH SPEED

XCVRSELECT[1:0]=00

TERMSELECT=0

CHIRP MODE

XCVRSELECT[1:0]=00

TERMSELECT=1

LS[1]

LS[0]

SE0

Squelch

FS-J

!Squelch

!Squelch &

HS Differential Receiver

Output

FS-K

Invalid

!Squelch &

!HS Differential Receiver

Output

SE1

Invalid

Table 7.2 Host Linestate States (DPPD & DMPD = 1)

STATE OF DP/DM LINES

LINESTATE[1:0]

LOW SPEED

XCVRSEL[1:0]=10

TERMSELECT=1

FULL SPEED

XCVRSEL[1:0]=01

TERMSELECT=1

HIGH SPEED

XCVRSEL[1:0]=00

TERMSELECT=0

OPMODE=00/01

CHIRP MODE

XCVRSEL[1:0]=00

TERMSELECT=0

OPMODE=10

LS[1]

LS[0]

SE0

Squelch

LS-K

FS-J

!Squelch

!Squelch &

HS Differential

Receiver Output

USB3500 Datasheet(PDF) 31 Page - SMSC Corporation

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