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TPS23750: Technical issues

Part Number: TPS23750
Other Parts Discussed in Thread: TEST

Hi team,

I got a question from customer.

I use the 5V / 2A Poe power supply made by 23750. It can be used when it is just adjusted. However, if the load is added one way, and the applied current exceeds 200mA, it is abnormal. The power on is only about 3V. What is the reason for this? How should I deal with it. I've tested that the 50V output is stable.

TPS23750_SCH20210705.pdf

POE_23750_01.zip

In addition, I found that when this group of circuits is not used,50V is unstable. Is there any way to cancel led?

Thank you very much for your help.

Best regards,

  • Hello, 

    Can you explain more how if the load is added one way? Are you reversing the polarity of the load? How do we know that it is not the load that is drawing a different amount of current?

    What type of load is used? Resistive, Eload, system?

    It could also be the system is unstable, which probably indicates a component is incorrectly populated. 

    I also notice there are some resistors to ground or directly in the power path. Many resistors are marked R? so I cannot specify which ones. 

    My advice is to compare with HPA107 and note all differences (part selection included) to help understand how these boards behave differently. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • Hi Pahl,

    Thank you for your help.

    The component layout you mentioned,

    I have provided PCB diagram, please help me to see which part has problems.

    I just found the circuit of hpa107,

    The LED I added to C1 refers to the one added here.

    However, after this operation, 50V is unstable and intermittent output.

    So I added another 10K resistor.

    Now the problem is that 50V is stable, 5V output (more than 200mA) is unstable

    Please analyze it again,Thanks a lot.

    Best regards,

  • Hello,

    Can you show a labeled waveform of 50V and the output voltage?

    Without any load connected, how much power does the design draw?

    The PCB does not contain the labels that i asked for. Please have the customer enumerate the schematic. 

    Can you please answer the following?

    Can you explain more how if the load is added one way? Are you reversing the polarity of the load? How do we know that it is not the load that is drawing a different amount of current?

    What type of load is used? Resistive, Eload, system?

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • Hi Pahl,

    Thank you for your help.

    I got some information from customer.

    The mark waveform and output voltage of 50V are as follows:

    After the step-down output is 5V.

    I use this electronic load to test.

    The direction of the current is the same.

    In the case of no load connection, the power consumption is not required.

    Thanks a lot.

    Best regards,

  • Hey, 

    So it appears that everything in this schematic matches the HPA107. This could indicate that some component on the physical board is not the proper value or is damaged. 

    I suggest reviewing the physical board for each component. Additionally, I suggest ordering this EVM to compare waveforms. 

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments 

  • Hello, 

    Is there any update on this request?

    If this post answers your question, please indicate so by marking this thread as resolved. Thank you.

     

    Regards, 

     

    Michael P.

    Applications Engineer

    Texas Instruments