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LMG3422R030: VI characteristics of LMG3422R030 to estimating Conduction loss

Lee inho
Prodigy 40 points
Part Number: LMG3422R030


Hello, I'm writing to ask you something about LMG3422R030 module's VI characteristic and thermal characteristic.

In the file which name is "LMG342xR030 600-V 30-mΩ GaN FET With Integrated Driver", Datasheet, 

There is no information about VDS - IDS characteristic curve, RDS(on) - IDS characteristic curve. 

I need the information of these characteristic to estimating junction temperature with power loss(conduction loss + switching loss)

how can I get these information? or there is another way to carry out junction temerature estimation?

and, about thermal characteristic, I want to get some information about RC thermal network's R,C values. 

In the datasheet, Thermal information is already existed, but to estimate the junction temperature of GaN HEMT, I need Cauer or Foster network constant value. 

if there are some ways to get information, plz tell me.

In addition, LMG3422R030 module consists of Normally-ON GaN HEMT and Si-MOSFET. 

If there is no information that I mentioned, Please tell me the model name of GaN HEMT and Si-MOSFET that make up LMG3422R030.

Thank you for reading.

  • 0
    TI__Expert 4520 points

    Hello,

    To answer your first question: at the time of publication, the LMG342xR030 I-V curve was not ready to be released and therefore not included for the time being. The datasheet will be updated to include this figure; however, in the meantime you can refer to Figure 6-5 of the LMG3522R030 datasheet for this information as the curves will be very comparable.

    We do have varying thermal information for our devices, but access at this time is difficult with the holidays. After the new year I can speak with other members of my team and report back which thermal information specifically we have for the LMG3422R030.

    Regards,

    Zach

  • 0 in reply to Zachary Soviero
    Prodigy 40 points

    First, thank you for your answer.

    it is resolved about V-I characteristic issue. thank you.

    but, I'd like to get a more specific answer about LMG3422R030's thermal network information.

    As you said, I understand that it is difficult to answer the information right away with the holydays.

    I really hope you have a comfortable and enjoyable holyday.

    What I want to ask is, can I understand that I can get the Foster or Cauer thermal model's RC values after you talking with the team members later?

    Thank you for reading.

  • 0 in reply to Lee inho
    TI__Expert 4520 points

    Thanks for the clarification, 

    As soon as our Mechanical team is available I will reach out and provide you with an update.

    Thank you for the holiday wishes,

    Zach

  • 0 in reply to Zachary Soviero
    TI__Expert 4520 points

    Hello,

    I have the Foster Network data to share with you for our LMG342XR030 device:

                       

    Junction
    Self heating
    τ (s) R (Ω) C (F)
    1.13243E-05 0.001088 0.010409
    5.48817E-05 0.007622 0.0072
    0.000455987 0.051247 0.008898
    0.007871467 0.010691 0.736267
    0.061607379 0.127559 0.482972
    0.234120386 0.099504 2.352874
    0.725287437 0.02695 26.91257
    7.403539244 0.000772 9595.933

    Please let me know if this is the information you were looking for, or need any further explanation.

    Regards,

    Zach

  • 0 in reply to Zachary Soviero
    Prodigy 40 points

    Thank you for your reply.

    The Foster model constants you provided consists of 8 stages in total.

    Does the LMG342XR030 device have 8 layers inside?

    I would like to make sure that the information you provided is correct for the Junction to Case information.

    Thank you for reading.

  • 0 in reply to Lee inho
    TI__Expert 4520 points

    Hello,

    The "stages" as you mentioned in the Foster model do not correspond to physical locations or layers within the device. Together all stages represent the entire system but are derived from iterative calculations that do not hold meaning by themselves. This applies for all Foster models, if you have any further questions let me know.

    Regards,

    Zach

  • 0 in reply to Zachary Soviero
    Prodigy 40 points

    Hello,

    Thank you for information.

    I have some more question of thermal modeling.

    What I know is the foster and cauer model are possible to transform into each other.

    when I transform cauer model to foster model, if cauer model has 7 RC terms, the transformed foster model also has 7 RC terms.

    Cauer model's layer has a each layer's property.

    If foster model doesn't have phyical layer characteristic, then how I get information of layer's characteristic?

    or could you give me cauer RC constants?

  • +1 in reply to Lee inho
    TI__Expert 4520 points

    Hello,

    As you mentioned, the Foster model can be transformed to a Cauer model, which by definition has physical meaning for each RC constant since they are all referenced together. Given that the original Foster model does not have physical properties for the device, if you then transform that into a Cauer model, I don't believe it would represent the actual layers, just arbitrary layers that together form the device. 

    For our example, given our Foster model with 7 terms, the transformed Cauer model may also have 7 terms which can now be manipulated but there was never information about layers to start with so this information must be added. This area is not a specialty of mine, but I believe that is how the process works. Our mechanical team is currently working on an urgent customer support issue, but I can speak with them on Monday and get a more clear picture as to how the models works and if we also have a Cauer model or some other physical representation to use.

    Regards,

    Zach

  • 0 in reply to Zachary Soviero
    Prodigy 40 points

    Hello.

    Is there any cauer network information that i can use? 

    thank you.

  • +1 in reply to Lee inho
    TI__Expert 8960 points

    Hello Lee,

    We do not have Cauer network data.

    Thanks,

    Travis