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TUSB322I

SLLSEO5C – OCTOBER 2015 – REVISED MAY 2017

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Copyright © 2015–2017, Texas Instruments Incorporated

8.2.3.2 Detailed Design Procedure

The TUSB322I device supports a VDD in the range of 4.5 V to 5.5 V. In this particular case, VDD is set to 5 V. A

100-nF capacitor is placed near VDD.

The TUSB322I device is placed into I2C mode by either pulling the ADDR pin high or low. In this case, the ADDR

pin is tied to GND which results in a I2C address of 0x47. The SDA and SCL must be pulled up to either 1.8 V or

3.3 V. When pulled up to 3.3 V, the VDD supply must be at least 3 V to keep from back-driving the I

2C interface.

The INT_N/OUT3 pin is used to notify the PMIC when a change in the TUSB322I I2C registers occurs. This pin is

an open drain output and requires an external pullup resistor. The pin should be pulled up to VDD using a 200-kΩ

resistor.

The DIR pin is used to control the mux for connecting the USB3 SS signals to the appropriate pins on the USB

Type-C receptacle. In this particular case, a HD3SS3212 is used as the mux. To minimize crossing in routing the

USB3 SS signals to the USB Type C connector, the connection of CC1 and CC2 to the TUSB322I is swapped.

When swapping the CC1 and CC2 connection, the CABLE_DIR register will also be reversed (0 = CC2 and 1 =

CC1).

The Type-C port mode is determined by the state of the MODE_SELECT register. When the MODE_SELECT

register is 2'b01, the TUSB322I device is in UFP mode. The TUSB322I will exit the UFP mode if the

MODE_SELECT register is changed, I2C_SOFT_RESET is set, or EN_N pin is transitioned from high to low.

The VBUS_DET pin must be connected through a 900-kΩ resistor to VBUS on the Type-C that is connected. This

large resistor is required to protect the TUSB322I device from large VBUS voltage that is possible in present day

systems. This resistor along with internal pulldown keeps the voltage observed by the TUSB322I device in the

recommended range.

The USB2 specification requires the bulk capacitance on VBUS based on UFP or DFP. When operating the

TUSB322I device in a UFP mode, a bulk capacitance between 1 µF to 10 µF is required. In this particular case,

a 1-µF capacitor was chosen.

8.2.3.3 Application Curves

Figure 13. Application Curve for UFP in I2C Mode