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UCC27611: UCC27611

Milarepa
Expert 1670 points
Part Number: UCC27611
Other Parts Discussed in Thread: LMG1020,

Hi,

I need a low side gate driver for 200V EPC2304. Source and sink currents of 2A / 5A are fine.

I find UCC27611, LMG1020 and some more.

Could you please compare and suggest which is the best one to use. 

Also please give the link for the application example for selection of associated passive components.

Thank you.

  • 0
    TI__Expert 6035 points

    Hi Milarepa,

    For driving a GaN device, I would recommend using the LMG1020, as it has a higher source/sink current and much faster timing characteristics at a voltage geared towards GaN power devices (5V). It' also has a much smaller footprint.

    I'm assuming you mean gate resistors when you said passive components, so here is a tech note regarding gate resistor design: https://www.ti.com/lit/an/slla385a/slla385a.pdf.

    Thanks,
    Rubas

  • 0 in reply to Rubas Khalid
    Expert 1670 points

    Thank you for the suggestion.

    I have few more questions.

    1. Recommended gate drive for 200 V EPC2304 is a 12 V half bridge driver by EPC. LMG1020 is a 5V low side driver. Will using 5V driver instead of 12 V driver create any issues. I need a low side driver only.

    2. LMG1020 is 7A/5A driver. Qg of EPC2304 is 25nC (100 V, 32 A) from its datasheet. Does Qg vary if VDS is changed to 200V.

    3. With Qg of 25nC, current rise time of around 3.5ns and fall time of 5ns can be obtained ? 

    Kindly reply.

    Thank you.

  • 0 in reply to Milarepa
    TI__Expert 6035 points

    Hi Milarepa,

    1. If you're using the EPC2304 in a low-side configuration, then you will only need a low-side driver. GaN FETs have a more limited gate voltage range, where you shouldn't be exceeding ~6V max, so the 5V driver would work perfectly.

    2. As VDS increases, the charge for Cgd (Crss) increases as well. This then ultimately increases the Qg value.

    3. Assuming VDD = 5V, we can find the Cg = Qg/VDD = 500pF. We can see that from the switching characteristics table below, the Cload condition is 100pF, so we can assume that the rise/fall time are increasing linearly with the Cload. Our Cg of 500pF is 5x the load condition, so scaling the rise/fall times up 5x should give a close estimate: tr = 1.875ns and tf = 1.75ns. This is assuming there's no external gate resistance.

    Thanks,
    Rubas

  • 0 in reply to Rubas Khalid
    Expert 1670 points

    Thank you for the reply. In the calculation of Cg as 500pF, you had taken Qg as 2.5nC. But the total gate charge from EPC2304 datasheet is 24nC (100V,32A).

    Could you please clarify this.

  • 0 in reply to Milarepa
    TI__Expert 6035 points

    My apologies, I probably mistyped while calculating. With Qg = 24nC, Cg = 4.8nF, which is 48x larger than the test condition. This yields an estimate of tr = 18ns and tf = 16.8ns.

    Thanks
    Rubas