DS00002103A-page 35

USB3500

6.13

HS Device Attach

Figure 6-8 demonstrates the timing of the USB3500 control signals during a device attach event. When a HS device is

attached to an upstream port, power is asserted to the device and the device sets XCVRSELECT and TERMSELECT

to FS mode (time T1).

ational range as defined in the USB 2.0 specification. The assertion of Device Reset (T0) by the upstream port will ini-

tialize the device. By monitoring LINESTATE, the Link state machine knows to set the XCVRSELECT and

TERMSELECT signals to FS mode (T1).

The standard FS technique of using a pull-up resistor on DP to signal the attach of a FS device is employed. The Link

must then check the LINESTATE signals for SE0. If LINESTATE = SE0 is asserted at time T2 then the upstream port is

forcing the reset state to the device (i.e. Driven SE0). The device will then reset itself before initiating the HS Detection

Handshake protocol.

FIGURE 6-8:

DEVICE ATTACH BEHAVIOR

TABLE 6-11:

ATTACH AND RESET TIMING VALUES

Timing Parameter

Description

Value

T0

Vbus Valid.

0 (reference)

T1

Maximum time from Vbus valid to when the device must

signal attach.

T0 + 100ms < T1

T2

(HS Reset T0)

Debounce interval. The device now enters the HS

Detection Handshake protocol.

T1 + 100ms < T2