11

TUSB321AI

www.ti.com

SLLSER2A – OCTOBER 2015 – REVISED MAY 2017

Product Folder Links: TUSB321AI

Submit Documentation Feedback

Copyright © 2015–2017, Texas Instruments Incorporated

7.4.1 Unattached Mode

Unattached mode is the primary mode of operation for the TUSB321AI 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 TUSB321AI device is powered up, the part enters unattached mode until a successful attach has been

determined. Initially, right after power up, the TUSB321AI device comes up as an Unattached.SNK. The

TUSB321AI device checks the PORT pin and operates according to the mode configuration. The TUSB321AI

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 TUSB321AI device communicates to the AP that the USB port is attached. This happens through the

ID pin if TUSB321AI is configured as a DFP or DRP connect as source. If TUSB321AI is configured as a UFP or

a DRP connected as a sink, the OUT1 and OUT2 pins are used. The TUSB321AI device exits active mode under

the following conditions:

•

Cable unplug

•

VBUS removal if attached as a UFP

7.4.3 Dead Battery Mode

Dead battery mode is defined as VDD not active. In this mode, CC pins always default to pull-down resistors.

Dead battery means:

● TUSB321AI in UFP with 5.1 kΩ ±20% pull-down resistors