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LM5137F-Q1: Question about LM5137F-Q1

Chase Jeong
Mastermind 7555 points
Part Number: LM5137F-Q1

Tool/software:

Dear TI experts,

My customer check the specification of LM5137F-Q1 for their new project. Their application is automotive seat controller.

And here are some questions.

1. Is it okay to make 12V/15A output per one phase?

2. Is it okay to tie 2 output phases to make 12V/30A output? They want to control 2 DC motors using this 12V/30A output.

3. I saw that LM5137F-Q1 is preivew status. Is it okay to get samples for evaluation?

4. Could you recommend other devices which can make 12V/30A output?

5. Can I know the schedule for RTM of LM5137F-Q1?

Best regards,

Chase

  • 0
    TI__Guru 73992 points

    Hi Chase,

    Yes, 12V/15A per phase is fine, and a two-phase output is also fine (see the EVM just released, 12V/20A, 2 phase). Please use the quickstart fie to assist with your design.

    Samples are available now. What is the input voltage here?

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    Mastermind 7555 points

    Dear Timothy,

    Thank you for your support.

    1. I am little confused, you mean that the setting of EVM is for 12V/20A, 2 phase, and theroically it can make 30A output using 2 phase?

    2. Input voltage is 48V car battery but also consider overvoltage and undervoltage.

    3. Is the sample which I can get now is final sample? 

    4. What is the schedule of RTM?

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Guru 73992 points

    Hi Chase,

    I just mentioned the EVM for reference - you would have to make changes to do 30A (inductor, sense resistor, etc.). We have samples on our website now, and final release is imminent.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    Mastermind 7555 points

    Dear Timothy,

    Thank you for your support.

    My customer drew first schematic with LM5137F-Q1. Could you review it including the values of RLC components?

    - Please check that FET fits with output specification or not.

    Toshiba_XPH4R10ANB.pdf

    - Could you recommend the spec. of inductor? (L8 and L9)

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Guru 73992 points

    Hi Chase,

    No, that FET is not suitable for a 5V gate driver. It must be a logic-level device with Rdson rated at Vgs = 4.5V.

    Send on a completed quickstart calculator so we can review component selection.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    Mastermind 7555 points

    Dear Timothy,

    Thank you for your support.

    Here are 2 quick start calculator which my customer provided. Please check these 2 files.

    LM5137F-Q1_quickstart_calculator_revB2_250313-1.xlsm

    LM5137F-Q1_quickstart_calculator_revB2_250313-2.xlsm

    And here is second schematic. Could you review it?

    And here are some questions from my customer.

    1. My customer set switching frequency to 400KHz for high current output. On the othere hands, Is there any advantage except smaller inductor if they set switching frequency to 2.2MHz?

    2. About I_ocp(over-current), Is 15A(max curent for 1 phase) right because my customer wants 30A output current using 2 phases?

    3. About sense resistor, the result based on the calculator sheet and datasheet are different.

    (1) It is 6 mohm based on the caculator sheet.

    (2) Rs=3.38mohm (assume that I_out(cl)=15.5, △I_L=4.5(30% of 15A))

    Rs1 and Rs2 =2.86mohm (assume that I_LO1(PK)=17.5)

    (3) Please check that which one is right. (between calculation sheed and datasheet.)

    4. About inductor, Recommended value is 8.4uH. Is it okay to change the value to 4.7uH?

    Please check this issue. Thanks.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Guru 73992 points

    Chase,

    1. Given the high current, 400kHz is better for thermals.

    2. OCP in the quickstart calculator is entered based on the total current (not the per-phase current).

    3. Check that the total current is entered for Iout.

    4. Use the value to get approximately 30% ripple current. This is usually close to the recommended value base don slope compensation requirement.

    Regards,

    Tim

  • 0 in reply to Timothy Hegarty
    TI__Guru 73992 points

    Use 3mΩ sense resistance and 4.7uH inductor. Take a look at the 2-phase EVM I just released: https://www.ti.com/tool/LM5137F-Q1-EVM12V.

    Most important, note the EN1 and EN2 pins cannot be directly tied together for the ASIL B/D parts (i.e. the LM5137F-Q1), as this will cause the pin diagnostic to fail at startup. Use a 4.99kΩ in series with each pin (see the EVM schematic for example here).

    --

    Tim