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LMG1205: Maximum frequency of input souce

Chase Jeong
Mastermind 7645 points
Part Number: LMG1205

Hello TI experts,

My customer considers LMG1205 for their new product.

the question is, the input of LMG1205 is 7MHz pulse signal. Is it okay for LMG1205 to make proper output?

Best regards,

Chase

  • 0
    TI__Genius 9431 points

    Hi Chase, 

    Thank you for your question. What determines the maximum achievable operating frequency is the power consumption of the driver (how much power it can dissipate without exceeding the rated temperature of the device).  To estimate how much the device will heat up, you’ll need to know the worst case ambient temperature that customer expects, the FETs they are using, the VDD level and the switching frequency. 

    Then you can use the procedure provided in section 8.2.2.3 Power Dissipation of the datasheet to calculate the power dissipation of the device.  

    Once you calculate the power that the driver needs to dissipate, you can estimate the junction temperature (Tj) with the formula below and this should not exceed the recommended maximum TJ specified in the device datasheet (125C for this device): 

    Tj = (P * RθJA) + Ta

    where Tj = Junction temperature; RθJA = Junction-to-ambient thermal resistance (can be found in the driver's datasheet); Ta = ambient temperature (customer's maximum ambient temperature).

    Best regards,

    Leslie

  • 0 in reply to Leslie Marquez
    Mastermind 7645 points

    Dear Leslie,

    Thank you for your support, and sorry for later reply.

    Actually I don't understand clearly about it. could you give me some example if the ambient temperature is 70 degree?

    and i saw the graph in the datasheet below;

    the curve ends near 5MHz, and no curves after 5MHz. so it seems like it does not support over 5MHz.

    could you give me your opinion about this?

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Genius 9431 points

    Hi Chase, 

    The 5MHz just indicated that the data was collected up to 5MHz. The power consumption of the driver is what determines the maximum achievable frequency since the temperature rise must stay within the device's operating temperature.  

    Could you please also provide the FET part number and the VIN voltage?

    Best regards,

    Leslie