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TPS717: TPS717 Output voltage raise up during over current

Part Number: TPS717

We test the TPS717 input voltage is 5V, and output is 1.8V. The output load transient is 0A to 400mA as like the system load. We find the output voltage raise up during over current. As I know the voltage should be drop down. May I know why the voltage going up?

 

In addition. I know the TPS717 maximum current is 150mA. May I know the TPS717 can support an over current during short time pulse?

BR,

Gary

  • Hi Gary,

    Thanks for providing scope-shots. In order to understand the problem in your system, here is my comments and I also have a few questions that I may need your help on.

    1. The power on the LDO can be estimated by using (5V - 1.2V) x 0.4 = 1.52 Watts. The DRV package of this device has the best thermal among the three. The estimated temperature rise on DRV could be 108C (using Rja x power) from ambient 25C. It may exceed the recommended 125C junction temperature shortly after it is on.

    2. I understand you have pulse load and the device can output higher than 150mA for a short period of time, but the internal current limit of this device has a typical spec of 325mA. Once device's current limit circuit starts working, the current may be clamped around 325mA and your output will drop.

    3. Did you use active load to apply the 400mA on the output of the LDO? Like you said, when the current actually goes through the output of the LDO to your load, the voltage on the output should drop. Can you share more details on how you apply your load and what kind of load you were using? 

    4. In order to see if there is any other issue with your application, will you share your full schematic with TPS717 as well?

    Regards,
    Jason Song

  • Hi Jason,

    Thanks for your help.

    This load comes from the system which is the wifi module. As you mention that the Vout = 0.9xVout at current limit. The output voltage should be drop. May I know why the output voltage going up during the over current?

    BR,

    Gary

  • Hi Gary,

    Will you provide the schematic? If the schematic contains information you would prefer not to post on public forum, please add me as friend on forum and send me private message.

    Regards,
    Jason Song
  • Hi Jason,

    I have send the schematic in your internal email. Please have your recommends. Thanks.

    BR,

    Gary

  • As communication continues via emails, I am closing the post.