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TUSB321AI

SLLSER2A – OCTOBER 2015 – REVISED MAY 2017

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Table 2. Type-C Current Advertisement and Detection

TYPE-C CURRENT

UFP or DRP acting as UFP

Current Detection

DFP or DRP acting as DFP

Current Advertisement

Default

500 mA (USB2.0)

900 mA (USB3.1)

OUT1 = High

OUT2 = High (unattached) or Low (attached)

CURRENT_MODE = L

Medium - 1.5 A

OUT1 = Low

OUT2 = High

CURRENT_MODE = M

High - 3 A

OUT1 = Low

OUT2 = Low

CURRENT_MODE = H

(1)

Required; not in sequential order.

7.3.3 VBUS Detection

The TUSB321AI device supports VBUS detection according to the Type-C Specification. VBUS detection is used to

determine the attachment and detachment of a UFP. VBUS detection is also used to successfully resolve the role

in DRP mode.

The system VBUS voltage must be routed through a 900-kΩ resistor to the VBUS_DET pin on the TUSB321AI

device if the PORT pin is configured as a DRP or a UFP. If the TUSB321AI device is configured as a DFP and

only ever used in DFP mode, the VBUS_DET pin can be left unconnected.

7.3.4 Cable Orientation and External MUX Control

The TUSB321AI device has the ability to control an external/discrete MUX using the DIR pin. The TUSB321AI

detects the cable orientation by monitoring the voltage on the CC pins. When a voltage level within the proper

threshold is detected on CC1, the DIR pin is pulled low. When a voltage level within the proper threshold is

detected on CC2, the DIR is pulled high. If the direction polarity of the external MUX is opposite of the

TUSB321AI, the CC1/CC2 connection to USB Type-C receptacle can be reversed. The DIR pin is an open drain

output.

7.3.5 VCONN Support for Active Cables

The TUSB321AI device supplies VCONN to active cables when configured in DFP mode or in DRP acting as a

DFP mode. VCONN is provided only when the unconnected CC pin is terminated to a resistance, Ra, and after a

UFP is detected and the Attached.SRC state is entered. When in DFP mode or in DRP acting as a DFP mode, a

5-V source must be connected to the VDD pin of the TUSB321AI device after Attached.SRC. VCONN is supplied

from VDD through a low resistance power FET out to the unconnected CC pin. VCONN is removed when a

detach event is detected and the active cable is removed.

7.4 Device Functional Modes

The TUSB321AI device has three functional modes. Table 3 lists these modes:

Table 3. USB Type-C States According to TUSB321AI Functional Modes

MODES

GENERAL BEHAVIOR

PORT PIN

STATES(1)

Unattached

USB port unattached. ID, PORT

operational. CC pins configure

according to PORT pin.

UFP

Unattached.SNK

AttachWait.SNK

DRP

Toggle Unattached.SNK

→ Unattached.SRC

AttachedWait.SRC or AttachedWait.SNK

DFP

Unattached.SRC

AttachWait.SRC

Active

USB port attached. All GPIOs

operational.

UFP

Attached.SNK

DRP

Attached.SNK

Attached.SRC

DFP

Attached.SRC

Dead Battery

No operation. VDD not available

N/A

Default device state to UFP/SINK with Rd