• State
  • Locked Locked
  • Replies 7 replies
  • Subscribers 33 subscribers
  • Views 817 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPL8002

eli
Guru 13485 points
Other Parts Discussed in Thread: MSP430F247

Customer  have an issue w/ TPL8002-25PWR. 

in new prototypes , when setting control pins (in this case to `011111’) current drain increase above ~10mA. (instead of 20~50uA)

no such issue in recent prototypes. we had there 10k resistors in series to control pins, which removed in new prototypes.

Please advise about this phenomena and possible fixes.  ****  it is urgent  ****

 more details:

control pins driver:          MSP430F247, supply rails 2.57V, GND

TPL8002 supply:                                ±2.67V, GND

  • 0
    TI__Genius 9860 points

    Moving to I2C forum for support.

    -Ryan

  • 0 in reply to C. Ryan Land
    Guru 13485 points

    Need urgent help!!

    Can we set a conference call?

  • 0
    TI__Mastermind 30260 points

    Are you saying that every other combination of bits A-F will work?

    And only '011111' is failing?

    How many boards have you built? Does it fail on every board?

    If you replace a "failing" TPL8002 device on the new board with a "working" TPL8002 device on the old board, is the problem resolved?

    If you believe this is a quality concern, please contact your local TI sales team and request to return devices for failure analysis.

    If you believe this is a board-related issue, please share schematics from your last working prototype and your new, not working prototype.

  • 0 in reply to Brian Berner
    Guru 13485 points

    1. no specific decimal control combination in this issue (if at all) – we’re still investigating.

    2. we’ll check new prototypes w/ DCP of earlier / different batch.

    3. the only difference between old and new prototypes is 10k resistors in series to control pins.

     

    4. please advise if there’s any risk by driving control pins directly from MSP430. (VCC=2.6V)

    - mainly: DCP latch-up and possible noise coupling from MCU to analog section.

     

  • 0 in reply to eli
    TI__Mastermind 30260 points

    A 10kOhm resistor in series from the MSP430 to the TPL8002? This is not a good idea. 

    If you are using a ballast resistor (to limit current), consider using a 10Ohm resistor.

    If you want to use a pull-up (to VCC) or pull-down (to GND) resistor to keep the control inputs in a known state, then 10kOhm or even 100kOhm is okay.

  • 0 in reply to Brian Berner
    Guru 13485 points

    We also think that series resistors is not a good idea, that’s why we removed them.

    (but it may help to decouple noise from MCU to the analog section with the DCP)

     

    Ballast resistor to limit current – do you mean current through input protection diodes of DCP?

  • 0 in reply to eli
    TI__Mastermind 30260 points

    I am not sure what DCP means here.

    If you are referring to the Potentiometer itself, then we refer to these as DPOTs.

    Low resistance series resistors (1-10 Ohms) can be used to reduce noise but do not remove or de-couple like a choke or a de-coupling capacitor would. In my experience, "ballast" is an older term used to refer to current limiting when a load would attempt to draw more current than expected under steady state; therefore, a ballast resistor is not needed here.

    I probably wouldn't use any resistors between the MCU and the DPOTs control pins, but I would put an 0402 footprint and a 0-ohm resistor in case testing determines a resistor is needed.