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TUSB321AI

SLLSER2A – OCTOBER 2015 – REVISED MAY 2017

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Copyright © 2015–2017, Texas Instruments Incorporated

8.3 Initialization Set Up

The general power-up sequence for the TUSB321AI device is as follows:

1. System is powered off (device has no VDD). The TUSB321AI device is configured internally in UFP mode

with Rds on CC pins.

2. VDD ramps – POR circuit.

3. The TUSB321AI device enters unattached mode and determines the voltage level from the PORT pin. This

determines the mode in which the TUSB321AI device operates (DFP, UFP, DRP).

4. The TUSB321AI device monitors the CC pins as a DFP and VBUS for attach as a UFP.

5. The TUSB321AI device enters active mode when attach has been successfully detected.

9 Power Supply Recommendations

The TUSB321AI device has a wide power supply range from 4.5 to 5.5 V. The TUSB321AI device can be run off

of a system power such as a battery.

10 Layout

10.1 Layout Guidelines

1. An extra trace (or stub) is created when connecting between more than two points. A trace connecting pin A6

to pin B6 will create a stub because the trace also has to go to the USB Host. Ensure that:

–

A stub created by short on pin A6 (DP) and pin B6 (DP) at Type-C receptacle does not exceed 3.5 mm.

–

A stub created by short on pin A7 (DM) and pin B7 (DM) at Type-C receptacle does not exceed 3.5 mm.

2. A 100-nF capacitor should be placed as close as possible to the TUSB321AI VDD pin.

10.2 Layout Example

Figure 5. TUSB321AI Layout