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TPS5410: Output takes time to stabilize

Ryu Yamashita
Expert 2510 points
Part Number: TPS5410

Tool/software:

Hi team,

I have made some prototype boards and it takes about 200ms for the voltage to stabilize with the following waveform.
When another lot of IC was mounted on this board, the output was stabilized immediately.
Is there any possible reason for this phenomenon?

Regards,
Ryu.

  • 0
    TI__Genius 14185 points

    Hi Ryu,

    Are you able to share the layout with us?

    I will begin reviewing the schematic.

    Best regards,

    Ridge

  • 0 in reply to Ridge Lahti
    Expert 2510 points

    Hi Ridge,

    Layout attached.
    It seems to be an IC dependent phenomenon, any ideas as to the cause?

    Best regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Genius 14185 points

    Hi Ryu,

    What is the part number for the inductor? It appears that the inductor may be saturating.

    Is this waveform taken at load or with no load?

    Do you have an example of the proper behavior?

    The output capacitors are also very far from the inductor in the provided layout. If possible they should be placed closer to the inductor with the feedback trace routed to the capacitors. See the EVM example for reference: 

    Best regards,

    Ridge

  • 0 in reply to Ridge Lahti
    Expert 2510 points

    Hi Ridge,

    Thanks for the reply.
    I am using LBRNJ12565GL680MN (Taiyo Yuden).
    As for the load, the output current is 150mA.
    I understand about the layout.
    Is it still due to inductor saturation?
    Is there any countermeasure?

    Best regards,
    Ryu.

  • 0 in reply to Ryu Yamashita
    TI__Genius 14185 points

    Hi Ryu,

    Here are a couple things you can try:

    • remove the external compensation components and test using a tantalum capacitor as shown in Section 7.2.1 of the datasheet
    • Try testing without the series diode D44
    • Disconnect the buck from the load on the board and test using a resistive load

    Can you provide date us with the date code or a high quality image of the top of the package for both "good" and "bad" units?

    Best regards,

    Ridge