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TPS65982 - 5V output doesn't go away after device is removed

KUNVICHET LEE75
Prodigy 240 points
Other Parts Discussed in Thread: TPS65982

I'm using the TPS65982 to output 3 variable outputs, 5V, 12V and 20V.  When I used a type-C to type-C cable PN# 3027001-005M, bought from Digi-Key, the 5V doesn't get shut off when the device is removed, but the cable is still attached to the TPS65982 charger.  If the cable is removed, then the 5V is shut off.  I have never seen it behave this way at 12V or 20V.  Has anyone see this issue?  How can I prevent this? Are there differences in type-C cables.  when I use a generic cables from Amazon, they don't exhibit this behavior.

thanks,

Vichet

  • 0
    TI__Prodigy 140 points

    hi Vichet,

        According to type C speciication, VBUS will be shut off once device is removed. But in TPS65982, VBUS can also be switched to power the chip by an LDO when VIN_3V3 is not available. So is it possible that your VIN_3V3 was somehow unavailable so VBUS had to take the responsibility to provide power for the core circuit?

  • 0 in reply to Susan Xue
    Prodigy 240 points

    Hi Susan,

    VIN_3V3 is always on and available.  The TPS65982 is configured to be DFP only.  This occurs only with this particular cable when attached.  If I remove the cable from the source, then VBUS goes away.  

    thank you,

    Vichet

  • 0 in reply to KUNVICHET LEE75
    TI__Prodigy 140 points
    Is it possible to post part of the schematic?
  • 0 in reply to Susan Xue
    Prodigy 240 points

    Mostly we followed the TPS65982 reference design; however, we have a variable AC/DC power supply that feeds 5-20V into the PP_HV port and does not use PP_5V0 at all.  The 5V and 3.3V are always available for PP_CABLE and VIN_3V3, respectively.  The EFM32 is used to bridge between the TPS65982 (I2C1) and the DAC (SPI) on the AC/DC power side to adjust the power needed at the output.  I wasn't able to paste the schematic in here.

  • 0 in reply to KUNVICHET LEE75
    TI__Expert 6505 points
    HI,

    When you say you remove the device, do you mean the far end device? If so how is the cable still connected to both the devices then? Can you check the CC line on the far end. If the far end device is UFP/Sink the CC line should be having 0V when the device gets removed. The Source/DFP will turn off VBUS only on detecting the CC line state has changed.

    Regards,
    Arun
  • 0 in reply to Arun Menon
    Prodigy 240 points

    Hi Arun,

    Thanks for your reply.  

    I meant the UFP/Sink device is removed from the far end of the cable, but the cable is still attached to the DFP/Source side.  Yes, I agree when the UFP/Sink device is removed, VBUS should be shut off, but I'm seeing it turns off then come back on.  I'm not sure what's making it turn back on.  Attached are some waveforms.  

    thanks,

    Vichet

  • 0 in reply to KUNVICHET LEE75
    TI__Expert 6505 points

    Hi,

    In the Issue plot 2, I see the CC1 line toggling. That is not expected. Also Can you send me the plot where the far end device is unplugged?  I don't see that in plot2. 

    Can you use another Type-C cable from a different vendor and check? 

    Regards,

    Arun

  • 0 in reply to Arun Menon
    Prodigy 240 points
    Arun,
    Sorry, I forgot to update the figure numbers. Figures 1 & 2, from left to right, I used the same cable (PN: 3027001-005M). Figure 1 is when the cable and UFP/Sink device are attached. Figure 2 is when the UFP/Sink device is removed/unplugged, but cable still attached. So I think figure 2 is the one you want to see for your first question.

    Figure 3 & 4, I used a different cable, generic brand I bought from Amazon. Figure 3 is when the cable and UFP/Sink device are attached. Figure 4 is when the UFP/Sink device is removed, but cable is still attached. I've also used an Apple type-C and a Google Nexus type-C cables, and they worked as this one. At this point, I'm starting to believe there's something with this particular type-C cable. Let me know your thoughts.

    Thanks,
    Vichet
  • 0 in reply to KUNVICHET LEE75
    TI__Expert 6505 points

    Hi,

    It looks like a cable issue. Yes, I was mentioning Figure 2 when I mentioned plot 2. 

    Thanks & Regards,

    Arun

  • 0 in reply to Arun Menon
    Prodigy 240 points
    Arun,
    When I disable the V_CONN Supported feature in the TPS6598X Configuration Tool, it works. Before I had it set to VCONN as DFP Only.
    Which is the correct setting for this?

    Regards,
    Vichet
  • 0 in reply to KUNVICHET LEE75
    TI__Expert 6505 points

    Hi,

    The VCONN supply for the Cable is taken from the VBUS on the DFP side. Hence if VCONN is enabled with 'VCONN supported as DFP/UFP,' then VBUS volatge wont drop even if the Far end device is removed. If VBUS voltage drops to zero then the active E-marker cable wont respond to SOP' or SOP'' messages. 

    You can disable VCONN id you are not using a active cable.

    Regards,

    Arun