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  • TI Thinks Resolved

HD3SS3220: UFP, what voltage level on CC1 and CC2?

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Replies: 26

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Part Number: HD3SS3220

Hi,

I'm trying to debug a design that doesn't seem to be working.

What voltage level should I see on CC1 and CC2 when the cable is plugged in in both orientations? I have two board built and both work differently.

The design is self powered and thus does not take any power from VBUS. I read (somewhere) that there was a minimum capacitance retirement for the VBUS line in the USB spec, so I added 2 x 22uF caps to the design. This meant that when the cable was removed the voltage on VBUS fell very slowly. For now I have fitted a 10k resistor in parallel with one of the 22uF capacitors. What is recommended for capacitance on VBUS if the device takes no power from the upstream device?

Thanks,

Graham

  • In reply to Graham North1:

    sorry, the picture attached is type-C to A cable.

    Both EN_MUX and EN_CC need to be reset high, you can control together couple of ms.

    DIR should pull up to 3.3v

    if 3.3v on and 5v is off, it could damage the device

  • In reply to Brian Zhou:

    Hi Brian,

    I've been looking at this some more today.

    I don't think that ENn_MUX and ENn_CC can be tied together due to the voltage level thresholds of both pins, +3V3 won't hold ENn_CC in reset, and the max voltage for ENn_MUX is VCC33+0.3V (=3.6V). Please can you confirm.

    If I can ensure that 3V3 comes up at-least 2ms after 5V can I simply tie both reset pins to GND? As per Figure 7.2

    I am thinking of changing the design to make it Bus powered and power the HD3SS3220 from VBus and a 3V3 regulator connected to VBus and enabled once the 5V rail is stable. Would that seem like a better option?

    Thanks,

    Graham

  • In reply to Graham North1:

    Sorry, ENn_CC is 5v.

    bus powered design looks a good option.

  • In reply to Brian Zhou:

    Hi Brian,

    Is there a recommended circuit for driving the Enable pins if I power the circuit from VBus?

    How do I ensure that VBus never goes above 5V, how is this controlled?

    Thanks,

    Graham

  • In reply to Graham North1:

    You can use Vbus switch to control 5v.

    For Enable pin, recommend connect cap from VDD to Pin..

  • In reply to Brian Zhou:

    But if I am designing an UFP, what is used to tell the DFP that I only want 5V, not any other higher voltage?

    If the enable pin is tied to GND, what will a cap to VDD do?

    Thanks,

    Graham

  • In reply to Graham North1:

    so it's prefer to use separate supply for HD3SS3220, Vbus is only for Vbus_det pin. Vbus_det pin can handle 5-20v.

    Cap on EN pin  just to hold high for couple of ms during power up.

  • In reply to Brian Zhou:

    In a USB type C design which end determines/sets/requests a higher VBus voltage?

    Thanks,

    Graham

  • In reply to Graham North1:

    in USB-c  Power Delivery , the sink sends requests to the source and adjusts the VBUS voltage as needed.

  • In reply to Brian Zhou:

    Hi Brian,

    So as this is an UFP, this is the sink.

    Does the CC Controller in the HD3SS3220 request to the source or the USB device after the HD3SS3220?

    Thanks,

    Graham

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