USB3250

DS00002142A-page 36

8.11

Assertion of Resume

In this case, an event internal to the device initiates the resume process. A device with remote wake-up capability must

wait for at least 5ms after the bus is in the idle state before sending the remote wake-up resume signaling. This allows

the hubs to get into their suspend state and prepare for propagating resume signaling.

The device has 10ms where it can draw a non-suspend current before it must drive resume signaling. At the beginning

of this period the SIE may negate SUSPENDN, allowing the transceiver (and its oscillator) to power up and stabilize.

Figure 8-7 illustrates the behavior of a device returning to HS mode after being suspended. At T4, a device that was

previously in FS mode would maintain TERMSELECT and XCVRSELECT high.

To generate resume signaling (FS 'K') the device is placed in the "Disable Bit Stuffing and NRZI encoding" Operational

Mode (OPMODE [1:0] = 10), TERMSELECT and XCVRSELECT must be in FS mode, TXVALID asserted, and all 0's

data is presented on the TXDATA bus for at least 1ms (T1 - T2).

TABLE 8-8:

HS DETECTION HANDSHAKE TIMING VALUES FROM SUSPEND

Timing Parameter

Description

Value

T0

While in suspend state an SE0 is detected on the USB.

HS Handshake begins. D+ pull-up enabled, HS

terminations disabled, SUSPENDN negated.

0 (HS Reset T0)

T1

First transition of CLKOUT. CLKOUT "Usable"

(frequency accurate to ±10%, duty cycle accurate to

50±5).

T0 < T1 < T0 + 5.6ms

T2

Device asserts Chirp K on the bus.

T1 < T2 < T0 + 5.8ms

T3

Device removes Chirp K from the bus. (1 ms minimum

width) and begins looking for host chirps.

T2 + 1.0 ms < T3 < T0 + 7.0 ms

T4

CLK "Nominal" (CLKOUT is frequency accurate to

±500 ppm, duty cycle accurate to 50±5).

T1 < T3 < T0 + 20.0ms

FIGURE 8-7:

RESUME TIMING BEHAVIOR (HS MODE)

TXVALID

T0

T3

T4

T1

T2

'K' State

FS Idle ('J')

SUSPENDN

DP/DM

XCVRSELECT &

TERMSELECT

SE0

FS Mode

HS Mode

time