TUSB321AI

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SLLSER2 – OCTOBER 2015

Feature Description (continued)

Table 1. Supported Features for the TUSB321AI Device by Mode

PORT PIN

HIGH

LOW

NC

SUPPORTED

(DFP ONLY)

(UFP ONLY)

(DRP)

FEATURES

Port attach and

Yes

Yes

Yes

detach

Cable orientation

Yes

Yes

Yes

Current advertisement

Yes

-

Yes (DFP)

Current detection

-

Yes

Yes (UFP)

Active cable detection

Yes

-

Yes (DFP)

VCONN

Yes

-

Yes (DFP)

Legacy cables

Yes

Yes

Yes

-

Yes

Yes (UFP)

7.3.1.1 Downstream Facing Port (DFP) - Source

The TUSB321AI device can be configured as a DFP only by pulling the PORT pin high through a resistance to

device advertises USB Type-C current based on the state of the CURRENT_MODE pin.

When configured as a DFP, the TUSB321AI can operate with older USB Type-C 1.0 devices except for a USB

Type-C 1.0 DRP device. The TUSB321AI can not operate with a USB Type-C 1.0 DRP device. This limitation is

a result of backwards compatibility problem between USB Type-C 1.1 DFP and a USB Type-C 1.0 DRP.

TUSB321AI will remove the Rd from CC pins and present Rp on both CC pins.

7.3.1.2 Upstream Facing Port (UFP) - Sink

The TUSB321AI device can be configured as a UFP only by pulling the PORT pin low to GND. In UFP mode, the

TUSB321AI device constantly presents pulldown resistors (Rd) on both CC pins. The TUSB321AI device

monitors the CC pins for the voltage level corresponding to the Type-C mode current advertisement by the

attaching. As a UFP, the TUSB321AI device detects and communicates the advertised current level of the DFP

to the system through the OUT1 and OUT2 pins.

7.3.1.3 Dual Role Port (DRP)

The TUSB321AI device can be configured to operate as a DRP when the PORT pin is left floated on the PCB. In

DRP mode, the TUSB321AI device toggles between operating as a DFP and a UFP. When functioning as a DFP

in DRP mode, the TUSB321AI device complies with all operations as defined for a DFP according to the Type-C

Specification. When presenting as a UFP in DRP mode, the TUSB321AI device operates as defined for a UFP

according to the Type-C Specification.

7.3.2 Type-C Current Mode

The TUSB321AI device supports both advertising and detection of Type-C current. When TUSB321AI is a UFP

or a DRP connected as a sink, the OUT1 and OUT2 pins are used to inform the system the detected USB Type-

C current being broadcasted by the attached DFP. When TUSB321AI device is a DFP or a DRP connected as a

source, the CURRENT_MODE pin is used to advertise the USB Type-C current. The current advertisement for

the TUSB321AI device is 500 mA (for USB2.0) or 900 mA (for USB3.1) if CURRENT_MODE pin is left

unconnected or pulled to GND. If a higher level of current is required, the CURRENT_MODE can be pulled up to

to advertise high current at 3 A. Table 2 lists the Type-C current advertisements and detection.

Copyright © 2015, Texas Instruments Incorporated

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