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Original question:

TUSB321: CC logic controller as a SNK(UFP)

TUSB321: Device not working according to datasheet specification

Martin Likavec
Prodigy 160 points
Part Number: TUSB321

Tool/software:

Hello,

I found some issue and I don't understand what is the problem with my circuit. Or maybe with your TUSB321 device.?

Datasheet specify in UFP mode (port = GND), the OUT1 and OUT2 pin signalize the Type-C current of connected source. But this is not working. I tried various of usb sources and different cables and still the OUT1 and OUT2 is LOW. 

I measured the CC voltage. Check below the result.
- When I connect USB PD charger which support 5V/3A, the voltage on CC pin was around 1.7V. -> This voltage on CC pin is correct

- I tried usbC port on my dell dock which have max output current 1.5A. The voltage on CC pin was around 0.94V. -> This voltage on CC pin is correct

- At the end I also tried standard USB-A laptop port and the voltage on CC pin was around 0.4V. -> This voltage on CC pin is correct for low current 500mA/900mA.

In all test mentioned above the OUT1/2 = LOW. This is incorrect behavior and I am looking for some advice.

Please, look at my schematic below.

Thanks
Best regards,
Martin

  • +1
    TI__Mastermind 38925 points

    Hi Martin,

    The OUT pins are open-drain pins. These lanes need to be pulled-up to a voltage like VDD with something like a 200KOhm resistor in order for the pin the go high, with a 200Kohm resistor being a large enough resistor to make sure the pin goes down to 0V when pulled low.

    If the pin is not pulled-up, then it will not go above 0V. At the moment, is the OUT pins low no matter whether there is a connection or not?

    Thanks,

    Ryan

  • 0 in reply to Ryan Kitto
    Prodigy 160 points

    Hi Ryan,

    Thank you very much!

    I am now very angry that I overlooked it and have to modify the manufactured PCBs.

    I modified one board and it is working now.

    Thank again for your fast answer and solution.
    Best regards,
    Martin