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TPS25947EVM: TPS25947EVM can not 6A load.

user5230673
Prodigy 40 points
Part Number: TPS25947EVM

TPS25947EVM can not 6A load. 

RLIM = 549ohm (initial mounted)

Vin = 12V to 16V

The expected value of the maximum load is 6A .

But, it turned off at 1.1A.

All channel is the same symptom, 

I used electrical load, and the load is increased in 0.1A steps.

Could you please tell me the solution?

  • 0
    TI__Guru 62375 points

    Hi ,

    1. Are you testing startup?

    2. What is the value of cdvdt cap? 

    3. Is e-load used in CC or CR mode?

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Prodigy 40 points

    >1. Are you testing startup?

    What does the question mean?
    Under the following conditions, the voltage is output normally.
    TPS25947EVM has not been modified.

    12V to 16V to the input terminal (J16) of TPS25947EVM
    No load on the output terminal (J15)

    Connect the electronic load, increase the load in 0.1A step, and turn off the output at 1.1A.

    In 0.01A step, it was turned off at 1.03A.

    ＞2. What is the value of cdvdt cap? 

    It's Default setting of TPS25947EVM
    It is same result at following the setting of all.

    1. 3300pF
    2. 100ohm+0.01uF
    3. 100ohm+22nF

    >3. Is e-load used in CC or CR mode?

    It is CC mode

  • +1 in reply to user5230673
    TI__Guru 62375 points

    Hi,

    Can you tell which channel of EVM are you using?

    Are you first connecting load and then turning supply on or first connecting supply and then turning load on?

    Can you share a waveform showing input voltage, output voltage and current through efuse?

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Prodigy 40 points

    >Can you tell which channel of EVM are you using?

    All ch is the same symptom.

    >Are you first connecting load and then turning supply on or first connecting supply and then turning load on?

    First connecting supply and then turning load on

    >Can you share a waveform showing input voltage, output voltage and current through efuse?

    Could you please check the attached?

    EVM.xlsx

  • +1 in reply to user5230673
    TI__Guru 62375 points

    Hi,

    I see in the waveform that input voltage also starts falling when current is greater than 1A. Why is that happening? 

    Input voltage is going below undervoltage lockout threshold of 10.83V due to which device is turning off. 

    It looks that supply is not able to give current more than 1A due to which it is drooping. How much is current limit of supply?

    Regards

    Kunal Goel

  • 0 in reply to Kunal Goel
    Prodigy 40 points

    I'm sorry, your point out is correct.

    There was a problem with the operation of the using PS.
    I changed to another PS and the problem went away.

  • 0 in reply to user5230673
    TI__Guru 62375 points

    Okay. Thanks for confirming. Closing thread now.