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tps2384 voltage remains same after plug PD off

Minela gr
Prodigy 50 points
Other Parts Discussed in Thread: TPS2384

Hi,

I am using tps2384 and have following problem: When PD is connected, voltage read from register is ok, but when I disconnect PD, voltage value remains the same. In the other hand, tps current goes to zero.

If I execute POR (by writing to Common Control Write, Register Select = 0001, value 1= reset all circuits and start a POR timing cycle), voltage is set to 0 (for both ports). When connecting the device again, voltage is up. Is there something that I am missing, should I execute some sort of port reset when PD is disconnected? As I understood, device discovery should be performed itself. Again, I couldn't find way to reset values of just one port, is that possible? (If I disable only one port, voltage remains the same)

Thanks in advance for any help,

M

  • 0
    TI__Genius 15655 points
    Hi Minela,

    Which MPS method did you pick up? AC disconnect or DC disconnect? From the behavior you described, it looks like you the disconnect function was disabled. Usually, if you enable DC disconnect or AC disconnect, once the PD is removed from that port, the PSE should be able to detect this disconnection and remove the power on that port.
    How many ports were connect to PD devices? After you remove one device and reset the device, do you mean all the ports(including ports connected with PDs) shut off?


    Best regards,
    Penny
  • 0 in reply to Penny Xu
    Prodigy 50 points
    Hi,
    Thanks for your response.
    First: "Which MPS method did you pick up? AC disconnect or DC disconnect?"
    How can I check this?

    As for other information, I am using two ports (ports 1 and 3).
    When I read status (Register select 4), the result which I get is equal to 0. According to datasheet, load disconnect is noted with 100b in fault status section, so it should be ok?

    Here are the results of writing to control registers:
    - common write (Reg Select 0001 data 1) -> POR, both ports are reset and voltage goes to zero (but i dont want to reset both ports, only one)
    - write to one port: DC disconnect active (reg sel 2 data 0) and DC disconnect off (reg sel 2 data 1)- I don't see any effect
    - write to one port: ac low and ac high (reg sel 2 data 9, 10 ) - I don't see any effect

    Current on both ports seam to be measured correctly; it goes to 0 when I plug off power device. Also, I have tried it on more than one hw so it is not a hw issue.

    Any other idea what to test? I really have no other idea what is happenning here.

    Thanks in advance for response,
    M
  • 0 in reply to Minela gr
    TI__Genius 15655 points

    Hi Minela,

    Thanks for your information. If you don't have any preference on selecting DC disconnect or AC disconnect, we would suggest you go with the easiest way: DC disconnect.  To enable DC disconnect you only need to set register 0010 bit D4 to 0(leave AC high and AC low to its default value). 

    DC disconnect basically measures the port DC current,  and if the current is lower than the DC disconnect threshold for longer than the time out period, the PSE would shutdown the port automatically.

    Best regards,

    Penny

  • 0 in reply to Penny Xu
    Prodigy 50 points
    Hi Penny,

    Thanks again for answer. I have already tried that before and again now - there is no effect.
    When I read that register value it is set to 0 (which seems ok). Also when i read status register value, it returns 0, which means that there is no error in 'load disconnect' section.

    Any other ideas?

    Best regards,
    Minela
  • 0 in reply to Minela gr
    TI__Genius 15655 points
    Hi Minela,

    Thanks for your feedback. We will need more information to see why the DC disconnect doesn't work. Could you please send me the schematic and all your register settings?

    Best regards,
    Penny