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LMG1025-Q1: DC loading.

Simone Barletta
Prodigy 20 points
Part Number: LMG1025-Q1

Hi. I'm keen to know if this gate driver would be able to source a DC current to a load. In its datasheet, in the DC output section, is specified a value of 45mV voltage drop when IOUTH is 100mA so i'm guessing it has a DC output impedance of 0.45Ohms. Given that it's not designed for that... would DC operation of this IC only be limited by thermal dissipation? 

Thank you, SB.

  • 0
    TI__Genius 12990 points

    Hi Simone,

    Thanks for reaching out on e2e. When switching LMG1025 the output's source and sink current with a peak pulse of current to transition a capacitive load like the gate of a FET. The output resistance can be considered from this calculation, however this measurement is a test done that forces a DC current through the pull up and pull down to measure the output resistance. The part does not source or sink DC current by itself. Let me know if this helps answer your question or you have any more.

    Thanks,

  • 0 in reply to Jeffrey Mueller
    Prodigy 20 points

    Hi Jeff.

    FIrst of all thank you for your reply.

    I know that this IC is not a current source/sink but..

    Let's say that i'm trying to drive (very fast) only 1 power LED. In my design i was using a LMG1025 to drive a GaN FET to power the LED (in a similar way as described in yours LiDAR user guide snou150 ). That (coupled with a RL sweep-out path like in the following schematic) would've probably work great for very short pulses... . 

       

    But my needs changed and i need square (optical) pulses and this topology wouldn't work. So i thought: this drivers have the peaking capabilities to manage  the LED capacitance... if they're able to withstand a fraction of that current for a prolonged time i wouldn't need anything else to achieve my goal. 

    Thanks, SB. 

  • 0 in reply to Simone Barletta
    TI__Genius 12990 points

    Hi SB,

    1025 is not meant to drive the LED directly without a FET. However with some testing and validation, under certain operating conditions this could be possible. However like you said, thermals would be the limiting factor here.

    Thanks,