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TS12A12511: dual supply Vcc configuration for negative swing makes high overcurrent trouble

Dennis Oh
Prodigy 440 points
Part Number: TS12A12511

Hello Adam,

one of my customer configured dual supply Vcc(+/-5V) schematic to get +/-4V swing output.  COM should be output connected to load and NC, NO are applied from Vcc through resistor divider.  IN comes from   0~3.3V 150Hz swing.  so final target is to get  150Hz +/-4V swing on COM.  however, the application makes unexpected overcurrent trouble.  so, if Negative power supply(-Vcc) is replaced to GND, can see normal  0 ~ +4V 150Hz swing on COM.

would you review & find what the matter/error is here?    attached the schematic. 

 

  • 0
    TI__Mastermind 45575 points

    Dennis,

    Would you please describe more what is the unexpected over current trouble?  Is there extra current consumed by the TS12A12511 or is it consumed by the load, etc.  

    Does the extra current only happen during the transition on the IN pin?  What happens if you have the IN pin DC 0V or IN pin DC 3.3 V.  Does the issue go away?

    Do you have any scope captures of the unexpected behavior?  

    Does this post describe your issue? 

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    TI__Prodigy 440 points
    Adam,
    Thanks for support. Please let me share you details sequentially,
    1. the +/-5Vcc comes from charge pump. customer found the charge pump got shut-downed from overcurrent.
    2. connected DCDC converter and found the current consumption by TS12A12511 was higher than 800mA. there is no load connected on COM at the moment.
    3. removed TS12A12511 in order to verify abnormality on PCB, > can see no leakage/high current on the +/-5Vcc.
    4. if -Vcc is tied to ground, can find normal working as 0 ~ +4V 150Hz swing. (IN : 0 ~ 3.3V 150Hz control)

    will try to match the IN control level to Vcc_5V and to see whether improved or not.
    also, will find Icc w/ DC voltage(not swing) on IN.
  • 0 in reply to Dennis Oh
    TI__Mastermind 45575 points

    Dennis,

    1) What else is connected to the charge pump besides the TS12A12511?

    2) current consumption of 800mA of the TS12A12511 indicates to me that the TS12A12511 is damaged and has a short from Vcc to ground.  When I mentioned higher current consumption when logic is in an unknown state the Icc would be in the 1 to 10s of mA range not 100mA

    3) Does replacing the TS12A12511 with a fresh unit cause the issue to go away.  I suspect the unit is damaged if it drawing 800mA.

    4) Does the same unit that draws 800mA correct itself when -Vcc is connected to ground?

    Below are good next steps:

    5) will try to match the IN control level to Vcc_5V and to see whether improved or not.
    6) also, will find Icc w/ DC voltage(not swing) on IN.

    7) Place a new unit on board because I think the device is damaged and should not be drawing 800mA

    Thank you,

    Adam

  • 0 in reply to Adam Torma
    TI__Mastermind 45575 points
    Dennis,

    What is the latest update from your debug? Do you have additional data points to share or any new questions?

    Thank you,
    Adam
  • 0 in reply to Adam Torma
    TI__Prodigy 440 points

    Hello Adam,

    delivered DGK samples and Dip adaptor EVM to customer last week. will keep you updated once I get a feedback from him.

  • 0 in reply to Dennis Oh
    TI__Mastermind 45575 points
    Dennis,

    What did you hear back from the customer? They have had the EVM 3 weeks for testing. Did they learn anything new to share?

    Adam
  • 0 in reply to Adam Torma
    TI__Prodigy 440 points

    Hello Adam,

    Thanks for remind me of that.  found abnormal short on PCB thermal pad as root cause and closed this issue.  Thanks again for your support.

  • 0 in reply to Dennis Oh
    TI__Mastermind 45575 points

    Dennis,

    Glad to hear you found the root cause of the issue.

    Thank you,

    Adam