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LMQ644A2-Q1: output current in ambient temperature of 105℃

Daniel Wang (auto)
Expert 3540 points
Part Number: LMQ644A2-Q1
Other Parts Discussed in Thread: LM61495-Q1, , LM25149-Q1

Hello experts,

Our customer need to utilize a Buck converter to deliver 10A current at 5V under 105℃ ambient temperature in their ZCU project.

So they wonder if we did the relevant test for current output capability under high temperature, is there any test result we can offer to customers for the problem.

Thanks.

Best regards.

  • 0
    TI__Expert 3766 points

    Hi Daniel,

    For 10A output current, I also recommend LM61495-Q1 buck converter, which may suit your design parameters with a single phase, single output.

    LMQ644A2-Q1 configured in a 2-phase, single output solution will also suit your design parameters.

    For thermal data, the EVM user guides for LM61495-Q1 and LMQ644A2-Q1 has empirical testing for specific use cases which you can use to estimate thermals for your use case. There are also quickstart excel calculator which I've attached that have thermal estimations on junction temperature.

    LM(Q)64480_A0_A2_Quickstart_Tool_REVA.xlsm

    Regards,

    Henry

  • 0 in reply to Henry Kou
    TI__Expert 3540 points

    Hello Henry,

    Thank you for your reply.

    For LMQ644A2-Q1, after inputting work condition (5V, 10A @105℃) to the quick start tool, we found the junction temp would up to 180℃, so maybe one LMQ644A2-Q1 not very suitable for 10A output current.

    As you recommend LM61495-Q1 for the application, is there similar quick start tool for the device, so we can estimate if the part suitable or not.

    Thanks.

  • 0 in reply to Daniel Wang (auto)
    TI__Expert 3766 points

    Hi Daniel,

    After taking a look at your input conditions, it would seem that a controller with external FETs may be the best thermal solution for you. I also recommend LM25149-Q1 that can definitely support your output current. With an output of 5V, 10A, 105C ambient, I recorded 115C junction temperature with a thermally optimized board layout.

    Regards,

    Henry6165.LM5149-LM25149 Quickstart Calculator_rev3.xlsm