• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 595 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.

TPS92640: Ccomp problems

DavidLB
Prodigy 55 points
Part Number: TPS92640

Hi,

We used a TPS92640 to drive 4 leds in serie. In my last post we have had a problem with the low current start of TPS92640. To solve it, we changed the value from 300nF to 100nF. The TPS92640 starts better but we have problem with around this capacitor. In fact, sometime (randomly and not on all cards) this capacitor blocks the TPS. The oscillation is block on  Ron, no more drive of MOSFET and so on. We just change the capacitor with a new and everything restarts good. Sometimes we just remake solder.

to complete your information, we used an vishay  vj0805Y104Kxxcw1bc (X7R 10% ceramic)

Can you help me to understand the problem ? is this capacitor is good for the TPS? Is there another problem masked by our change of value?

Thanks for your help

David.

  • 0
    TI__Mastermind 28655 points
    Hello David,

    I assume you change to comp cap value to 0.1 uF? "The capacitor blocks the TPS" I don't understand this statement. The capacitor should be fine I think there is something else causing issues in your design. What is Vin, Vout, Iled, the start-up sequence, what is the power source and any other operation going on when powering up?

    Regards,
  • 0 in reply to Irwin Nederbragt
    TI__Mastermind 28655 points
    I have not heard back from you so I believe you may have solved the issue.
    The thread will close now but will reopen if you reply
  • 0 in reply to Irwin Nederbragt
    Prodigy 55 points

    Hi,

    I'm sorry.  I was abroad with a limited access to my mails and internet.

    the Vin is between 18 to 28Vdc, the Vout is between 5.4 to 6.1 for 2 leds , 10.8 to 12.2 for 4 leds and  13.5 to 12.3 for 5 leds. we drive the TPS via a numeric analogic converter and the iadj pin. The power supply is from Powerbox.

    If you have an email i can send you the schematic of our product.

    David