• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 255 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TPS40057 issue

David Woo
Prodigy 530 points
Other Parts Discussed in Thread: TPS40057

Recently, we found many failures in customer side. We have done some testing and we found that high dV/dt at SW may cause damage to IC. Can anyone confirm this to me? Thks.

  1. When the SW in tied to a voltage > 8V suddenly, it seems will cause failure to the IC. It seems that high dV/dt at SW can cause failure. Is it true? Have you seen this before?
  2. We can see there is a capacitor tied from ILIM to VIN. If there is high dv/dt input to this pin, will it cause failure to the IC?
  • 0
    TI__Guru 56925 points

    David,

     

    I am traveling, so my responses might be slow, but I am not aware of any dV/dt issues on the switch node of the TPS40057 controller.   During normal operation, the SW pin of the TPS40057 controller routinely switches between VDD and GND in the span of several nano-seconds.

    1) WHat level of dV/dt are you seeing at the SW pin?

    2) What failure mode are you seeing?

    3) How are you "suddenly raising SW to > 8V?

    4) How are the other pins of the TPS40057 connected?

     

    There is a capacitor from ILIM to VDD to allow the ILIM voltage to track the VDD voltage during line transients and switching ripple on VDD.  WIthout this capacitor, Line transients and VDD switching ripple can impact the accuracy of the current limit function.  This capacitor should result in higher dV/dt transients on the ILIM pin with respect to GND, but little to no dV/dt with respect to VDD.