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Soft Sart for LDO TPS79933DRV

Thomas Eder
Prodigy 20 points

Hello,

I've got the following problem when using TPS79933DRV in our design:

The input voltage supply in our design is able to supply approx. 250mA. After enabling the TPS79933 it charges the capacitors at its output rather fast, which causes a very high current peak. The input voltage then breaks down until the capacitors are charged. Other circuits, which are supplied by the same input supply voltage, perform a reset due to the breakdown of the input voltage. So is there a possibility to implement a soft start for the TPS79933 with a small application circuit to reduce charging current of the output capacitor below 200mA? Or is there a similar part, which incorporates a softstart function?

A LDO with current limit <=200mA and similar performance would be also fine, but I could not find a device on the TI homepage (TPS79933 has typical current limit of 400mA, max. 600mA).

Any ideas?

Thanks a lot in advance!

  • 0
    TI__Mastermind 41770 points

    Hi Thomas,

    There are a couple of solutions you can implement with this device.

    1) Increase the input capcitor so that it is equal or greater than the output cap.

    2) Decrease the output to lessen the amount of inrush current.

    3) Increase the CNR cap so slow down the output voltage rise during startup.

    Please let us know if this helps.

    Regards,

    Darwin