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TUSB321

SLLSEO6C – JUNE 2015 – REVISED AUGUST 2018

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Copyright © 2015–2018, Texas Instruments Incorporated

7.4.1 Unattached Mode

Unattached mode is the primary mode of operation for the TUSB321 device, because a USB port can be

unattached for a lengthy period of time. In unattached mode, VDD is available, and all IOs are operational. After

the TUSB321 device is powered up, the part enters unattached mode until a successful attach has been

determined. Initially, right after power up, the TUSB321 device comes up as an Unattached.SNK. The TUSB321

device checks the PORT pin and operates according to the mode configuration. The TUSB321 device toggles

between the UFP and the DFP if configured as a DRP. The PORT pin is only sampled at reset or power up.

7.4.2 Active Mode

Active mode is defined as the port being attached. In active mode, all GPIOs are operational. When in active

mode, the TUSB321 device communicates to the AP that the USB port is attached. This happens through the ID

pin if TUSB321 is configured as a DFP or DRP connect as source. If TUSB321 is configured as a UFP or a DRP

connected as a sink, the OUT1 and OUT2 pins are used. The TUSB321 device exits active mode under the

following conditions:

•

Cable unplug

•

VBUS removal if attached as a UFP