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TLV62595: Current flucuation

Xenon Li
Intellectual 1505 points
Part Number: TLV62595
Other Parts Discussed in Thread: TPS54527

Dear team,

One of our customers is using TLV62595 in their camera projects.

Recently, they found that when the NPU function of MCU is started, the current will fluctuate and affect the 12V to 5V buck converter5's output current. The followed the instruction of datasheet to choose components but output capacitor they chose is more than 200 uF since they said the lower output capacitor could not drive the NPU. 

What may cause these issues?

The waveform the customer tested is shown below:

                                 The output current waveform of TLV62595

                          The output current waveform of TPS54527

Thanks a lot for your support!

Best regards,

Xenon Li

  • 0
    TI__Guru*** 147190 points

    Hi Xenon,

    The output current should be changing, as the load operates.  Especially for processor loads, the load is typically very dynamic.

    We recommend operating with output caps within the recommended range of the D/S to ensure the stability of the device.

    Chris

  • 0 in reply to Chris Glaser
    TI__Intellectual 1505 points

    Dear Chris,

    Thanks a lot for your reply and support!

    I discussed with the customer again have a few more questions:

    1. The customer said if they set the output capacitor value as the datasheet mentioned, the NPU cannot be driven normally (The Arm based processor cannot work).

    2. The first waveform I found like the waveform that the converter working in OC protection mode, and I confirmed with the customer that the NPU works discontinuously, which is the characteristic of the NPU load. And the customer tried different output current capacity converters, even up to 16A with FCCM mode, the issues still exist.

    3. The howling occurred when the NPU started working.

    I am not sure why the output capacitor will influence the NPU working status, I think it will influence transient response and bandwidth. 

    Could you please share your opinion on this case? By the way, can we choose multiphase buck converter to drive NPU?

    Really appreciate your help!

    Best regards,

    Xenon 

  • 0 in reply to Xenon Li
    TI__Guru*** 147190 points

    Ah, the NPU is not working.  That was not initially understood.

    Please send me the schematic, BOM, and layout and waveforms via email.  We need to debug this.

    Chris