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LM5176EVM-HP: Is is possible to use lm5176 under the conditions? @ Vin : 53.3 ~ 55 V / Vout : 52.65 V / Idc : 2 A [CC/CV mode]

Sangmin Park
Prodigy 70 points
Part Number: LM5176EVM-HP
Other Parts Discussed in Thread: LM5085, LM5176

I need a DC/DC converter for battery charge.

In detail, CC/CV Mode is needed and the operating parameter is Vin : 53.3 ~ 55 Vdc / Vout : 52.65 Vdc / Idc : 2 A

before, i tried to use lm5085. But i was fail i think because of maximum duty ratio limitation of the ic.

Now, i try to use the lm5176. before make a own design board, i want to confirm the required performance by using lm5176EVM.

Operating range of the EVM module is Vin : 6 ~ 36 Vdc / Vout : 12 Vdc / Idc : 12A / Fsw : 250 kHz.

So, I will change some component for my required performance of DC/DC.

I insult the file about change point. plz check and give any advice.

And also i hope to get simulation file based on TINA under the my parameters.

When i export the simulation file based on TINA from WEBENCH POWER DESIGNER, the results is not as expected.

Looking forward to your reply.lm5176_EVM_Calculator Results.pdflm5176_EVM_Change Components.pdf

  • 0
    TI__Mastermind 21720 points

    Hi Sangmin,

    Thanks for reaching out with your question and for considering the LM5176 in your design.

    The engineer that supports this device is out on holiday. Please expect a replay within one week.

    Thanks,

    Garrett 

  • 0
    TI__Guru 58215 points

    Hello Sangmin,

    With 55V input voltage, you are at the maximum recommended value for the input voltage. You need to be very careful to stay below the 60V abs max rating of the converter when operating at this high input voltage. 

    For the given output power, I expect that one transistor at each position (4 in total) should be enough.

    During testing you might find that updating the compensation might be necessary as well, but the given one is a good starting point, I think.

    So I expect that your changes are ok.

  • 0 in reply to Brigitte
    Prodigy 70 points

    I have a problems using LM5176EVM about CC/CV operation mode.

    before test the CC/CV mode, I was change the parameters of default EVM board like below.

    Target current is 2 A.

    I didn't change the voltage setting. Because i want to check CC/CV mode before i change the parameters what i need V,I.

    But when i test on change the sense resistors, the current output have a ripple.

    So. i remove a cap. of SS pin to decrease the ripple of current.

    But the results like below.

    With the resistor : 5 ohm @ 12 Vout. operation looks okay with a little ripple current.

    but, when i reduce the resistor under 5 ohm like 4 ohm. Ripple current is very high.

    I need battery charger. it means load of converter is very low.

    According to the results, when use the lm5176 CC means only control the average current with high current ripple.

    Is it right? plz check my issues and reply.

    @ Input voltage of power supply is setting 12 V and max current limit is 60 A.

  • 0 in reply to Sangmin Park
    TI__Guru 58215 points

    Hello Sangmin,

    If you are using an average current sense resistor of 25 mohm, the average output current will be limited to 2A which is lower than the load current when you are using a 4 ohm resistor as load, so the device needs to reduce the output voltage when the current is too high.

    Please check a bigger SS value.

  • 0 in reply to Brigitte
    TI__Guru 58215 points

    Hello Sangmin,

    I expect that you have been able to solve the issue with the LM5176 average current limit. I will close this thread now. If my assumption is wrong, please post some more information about the issue in this thread of it this is locked, start a new one.