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LM2103: Operating with 100% dutycycle

Ricardo Pastore
Prodigy 90 points
Part Number: LM2103

I need to use 2 LM2103 to drive a full bridge DC motor controller. May I use the driver with a 100% duty cycle (always ON) in both switches (high side and low side)?

  • 0
    TI__Genius 10205 points

    Hey Ricardo,

    Thank you for your question regarding the LM2103.

    When using a half-bridge driver like the LM2103, you cannot have both sides (high and low) on at the same time or you go into a scenario called shoot through. Shoot through is when current flows directly to ground and bypasses the load due to both FETs being on at the same time.

    Let me know if you have any further questions.

    Thank you,

    William Moore

  • +1 in reply to William Moore
    Prodigy 90 points

    Thank you William 

    Sorry, I was not clear in my question. What I mean is can I have a scenario with 100% ON in the high side  MOSFET and  100% off in low side  MOSFET?

    Or we have a maximum duty like 95%. 

    Thank you

    Ricardo

  • 0 in reply to Ricardo Pastore
    TI__Genius 10205 points

    Hey Ricardo,

    When trying to run in 100% ON condition, the high side will deplete the bootstrap capacitor because it is driving the high side FET. There are ways to do this and bias the high side channel. You can take a look at the implementation at the FAQ at this LINK to see more on how to do that.

    Let me know if you have any other questions.

    Thank you,

    William Moore