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TPS51397A: Voltage drop issue when running high work load

Part Number: TPS51397A

Dear TI Team,

We are using TPS51397ARJER part in our design and we are seeing voltage is being dropped while running high workload.

Below is the scope shot of one of the power plane which derived from this power regulator output. 

Currently mode is set for ECO mode. What will be the reason for such high voltage drop.? is it an expected behavior or what will be causing this issue.?

Whether this is happening because device is going to ECO mode.?

Please find the attached schematics section as well, kindly review the same and provide your input on the same.

 TI TPS51397ARJER.pdf

Best Regards,

Vyshnav Krishnan

  • Hi Vyshnav,

    Thanks for reaching to us!

    1. Could you capture the load current waveform? Especially for 'high dynamic load', I want to understand your loading behaviors, Iout_max/Iout_min/time.

    2. Your waveforms seem to be coupled by noise. Could you use ground spring (as below) to measure the voltage across output cap? Also you may set the probe bandwidth to smaller like 20MHz to filter the high-frequency noise. 

    3. I have a hypothesis, in 'high dynamic load' period, your loading current may change really fast, doesn't give time for the device to respond to the load changes. If you want to improve load transient performance, you could try to increase the Cout or decrease the L.

    Look forward to your new waveforms. Let me know if you have more questions.