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Original question:

SM72295: SM72295: More Questions about SM72295 Implementation and Design Review

SM72295: Gate driver is not giving output please help

Derick Mathew
Prodigy 55 points

Part Number: SM72295

Hai, I am using SM72295MA IC for gate driver for the flyback converter of solar microinverter, which is same as the TI micronverter reference design. I am not able to get output from gatedriver. Pulses up to Gate driver input I have verified. 5V at Vdd and 12V at VCCA varified. Please help me to correct my mistake. schematic is attached.

  • 0
    Prodigy 55 points

    Input pulse to the gate driver ic is attached 

  • 0 in reply to Derick Mathew
    TI__Genius 14135 points

    Hey Derick,

    Thank you for your question regarding the SM72295.

    1. What is the purpose for the pulldown resistors on your input R89 and R90? There are internal pulldown resistors on the input in the device of 200kOhms. Often we see a capacitor here instead as an RC filter for input filtering.
    2. Are the input waveforms shown the measurement of the input at the gate driver IC pins? Just a note here, ensure that there is deadtime between the signals so you do not have both outputs high at the same time and experience shoot through. It appears that they are very close together here based on the scale of this scope capture.
    3. The OVS pin (Pin 16) should be connected to a resistor divider with the reference of Vdd. Currently, you are not using this over voltage sense feature.
    4. Have you considered using on of our half-bridge drivers here?
    5. Can you take waveform captures of HOA, LOA, VDD and VCCA at the gate driver IC pins?

    Let me know your findings from my questions and if you have any further questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    Prodigy 55 points

    Thank you William Moore for your reply.

    We were using the reference design of TI microinverter (TIDM-SOLARUINV) schematic. The difference is that in the reference schematic TI used both half bridges (since they are using interleaved flyback) but in my schematic I used only one half bridge. Schematic of TI reference is attached below:

    From the SM72295 datasheet, I understood that for LOA, we needed to connect VCCB, which we missed in the present schematic. We are modifying the PCB accordingly. Hope that it will work.

    Thank you

  • 0 in reply to Derick Mathew
    TI__Genius 14135 points

    Hey Derick,

    It looks like you are correct, that VCCB and VCCA are required for both channels as VCCA is used for the high-side of A and the low-side of B and VCCB is used for the high-side of B and the low-side of A.

    Let me know what your findings from this modification are and if you have any further questions or follow ups on my previous questions.

    Thank you,

    William Moore

  • 0 in reply to William Moore
    TI__Genius 14135 points

    Hey Derick,

    Were you able to resolve this issue? If so, please let me know if connecting both VCCA and VCCB worked or if you found another solution.

    If not, please update me on the status of this so that I can help you get this figured out.

    Thank you,

    William Moore