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TLVM23615: Output Spike and PFM Operation at Light Load

Conor
Guru 12115 points
Part Number: TLVM23615

Tool/software:

Hi Support Team,

We are currently evaluating a compact board using TLVM23615RDNR under the following conditions:

  • VIN: 24V

  • VOUT: 5.02V

  • IOUT: approx. 100mA

  • FSW: 1MHz (set via RT pin)

Under this condition, we observe spike noise of approximately ±100mV on the 5V output line.
Please find the attached scope waveform. Could you advise if such spike behavior is expected from this device under normal operating conditions?

Additionally, the observed ripple frequency is approximately 250kHz, which is lower than the set switching frequency of 1MHz.
We assume this is due to the device transitioning into PFM mode automatically under light load. Could you confirm if this understanding is correct?

We appreciate your support and look forward to your guidance.

Best regards,
Conor

  • 0
    TI__Expert 4465 points

    Hi Conor

    1) I would suggest to use a tip and barrel method to observe the output voltage, because the ground loop formed by normal scope probes pick up noise and you may see unwanted spikes. Below is the image of tip and barrel arrangement.

    2) Yes, you are absolutely correct, the devices goes in PFM at light loads.

    Hope the above technique helps. Let me know if you need further assistance.

    Thanks,

    Pramanik Patel