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[FAQ] TUSB320LAI: Which pins on TUSB320LAI are non fail safe and are there any special considerations for these pins?

Malik Barton57
Guru 64326 points
Part Number: TUSB320LAI
Other Parts Discussed in Thread: TUSB320HAI

When using TUSB320LAI or TUSB320HAI are there any non fail safe pins? Which pins are non fail safe and what special considerations do I need to take into account when designing a Type-C system with TUSB320LAI or TUSB320HAI? 

  • 0
    TI__Guru 64326 points

    Hi

    TUSB320LAI and TUSB320HAI have non-fail safe pins, listed below:

    • VBUS_DET
    • ADDR
    • PORT
    • ID
    • OUT[3:1] (SDA/SCL)

    These pins could back-drive the TUSB320LAI or TUSB320HAI devices if not handled properly. When TUSB320LAI or TUSB320HAI are back powered the internal state machine can enter an unknown state, causing device detection errors and status outputs malfunctioning. 

    When necessary to pull the non fail-safe pins up, it is recommended to pull-up PORT, ADDR, INT_N/OUT3, and ID to the device VDD supply. If a external supply is preferred please make sure the TUSB320LAI or TUSB320HAI supply voltage are stable at the appropriate levels before the pull up voltages for the non fail safe pins. The VBUS_DET must be pulled up to VBUS through a 900-kΩ resistor. When using the 3.3 V supply for I2C (SDA/SCL), the end user must ensure that the VDD is 3 V and above. Otherwise the I2C (SDA/SCL) may back power the device.