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Original question:

BQ25756: Using GAN FET chip (EPC23102ENGRT) with the Buck Boost Controller

BQ25756: Using GaN FET

Shahzad Hafeezi
Prodigy 50 points
Part Number: BQ25756

Tool/software:

Hi,

Can we use GaN FET "IGC033S10S1XTMA1" for main Mosfets ?

We are struggling with heat management with current Mosfets (GT010N10TL) used.

  • 0
    TI__Expert 6605 points

    Hi,

    GaN FETs are not compatible with the BQ25756.

    I believe that the GT010N10TL will not work with the BQ25756 either. In Section "9.2.1.2.8 Power MOSFETs Selection," the datasheet says this:

    • "It is recommended to limit the total switch node capacitance CSW (nF) < 160/VIN; for example, for a 60-V application, it is recommended to keep the total CSW < 2.67 nF"

    The Coss of the GT010N10TL is 4220 pF, which is very high. I would like to look into the MOSFET selection to help find a MOSFET that works with your application.

    1. What is the input voltage and current?
    2. What is the output voltage and current?
    3. Can you provide the waveforms on the SW1 and SW2 nodes with the current configuration?

    Best regards,
    Michael Bradbourne

  • 0 in reply to Michael Bradbourne
    Prodigy 50 points

    Hi Michael,

    Thanks for the feedback.

    Below are the answers:

    1. What is the input voltage and current?

    Solar Panel: 50V 10A
    Battery: 24V (or 48V) 15A

    2. What is the output voltage and current?

    LED Light: 48V 10A 

    3. Waveforms

    For now, we have all prototypes being damaged, we will try to sort out and see if waveforms can be extracted.

  • 0 in reply to Shahzad Hafeezi
    TI__Expert 6605 points

    Hi,

    The package you are using seems to have a pretty high Coss across the board. If this is indeed the reason for the MOSFETs to heat up, I might have to recommend a MOSFET with a different footprint. Is that going to be an issue?

    I have found that the IAUT165N08S5N029 MOSFET has a Coss of 790 pF, and I think the footprint is the same. This may work a little better, but that capacitance is still fairly high. It may be worth testing if the footprint cannot change.

    If you cannot provide the waveform, that is not that big of a deal. I just wanted to look to confirm if my suspicions about the Coss value are accurate.

    Best,
    Michael