USB3250

DS00002142A-page 14

6.1

Driver Characteristics of Full-Speed Drivers in Hi-Speed Capable Transceivers

The USB transceiver uses a differential output driver to drive the USB data signal onto the USB cable. Figure 6-1 shows

the V/I characteristics for a full-speed driver which is part of a Hi-Speed capable transceiver. The normalized V/I curve

for the driver must fall entirely inside the shaded region. The V/I region is bounded by the minimum driver impedance

above (40.5 Ohm) and the maximum driver impedance below (49.5 Ohm). The output voltage must be within 10mV of

ground when no current is flowing in or out of the pin.

TXDATA[7:0]

Setup time from signal to

CLKOUT

4ns

TXVALID

4

OPMODE[1:0]

4

XCVRSELECT

4

TERMSELECT

4

SUSPENDN

4

TXDATA[7:0]

Hold time from CLKOUT

to signal

0ns

TXVALID

0

OPMODE[1:0]

0

XCVRSELECT

0

TERMSELECT

0

SUSPENDN

0

FIGURE 6-1:

FULL-SPEED DRIVER VOH/IOH CHARACTERISTICS FOR HI-SPEED CAPABLE

TRANSCEIVER

TABLE 6-5:

DYNAMIC CHARACTERISTICS: DIGITAL UTMI PINS (CONTINUED)

Parameter

Symbol

Conditions

MIN

TYP

MAX

Units

0

0

Drive High

Test Limit

Slope = 1/49.5 Ohm

Slope = 1/40.5 Ohm

(mA)