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TUSB321

SLLSEO6C – JUNE 2015 – REVISED AUGUST 2018

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Feature Description (continued)

Table 1. Supported Features for the v Device by Mode

PORT PIN

HIGH

(DFP ONLY)

LOW

(UFP ONLY)

NC

(DRP)

SUPPORTED

FEATURES

Port attach and

detach

Yes

Yes

Yes

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

VBUS detection

-

Yes

Yes (UFP)

7.3.1.1 Downstream Facing Port (DFP) - Source

The TUSB321 device can be configured as a DFP only by pulling the PORT pin high through a resistance to

VDD. In DFP mode, the TUSB321 device constantly presents Rps on both CC. In DFP mode, the TUSB321

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

When configured as a DFP, the TUSB321 can operate with older USB Type-C 1.0 devices except for a USB

Type-C 1.0 DRP device. The TUSB321 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.

7.3.1.2 Upstream Facing Port (UFP) - Sink

The TUSB321 device can be configured as a UFP only by pulling the PORT pin low to GND. In UFP mode, the

TUSB321 device constantly presents pulldown resistors (Rd) on both CC pins. The TUSB321 device monitors

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

DFP. The TUSB321 device debounces the CC pins and wait for VBUS detection before successfully attaching. As

a UFP, the TUSB321 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 TUSB321 device can be configured to operate as a DRP when the PORT pin is left floated on the PCB. In

DRP mode, the TUSB321 device toggles between operating as a DFP and a UFP. When functioning as a DFP in

DRP mode, the TUSB321 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 TUSB321 device operates as defined for a UFP

according to the Type-C Specification.

7.3.2 Type-C Current Mode

The TUSB321 device supports both advertising and detection of Type-C current. When TUSB321 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 TUSB321 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 TUSB321 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

VDD through a 500-kΩ resistor to advertise medium current at 1.5 A or pulled up to VDD through a 10-kΩ

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