• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 30 subscribers
  • Views 332 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Question regarding TI reference design for BLDC motor inverter circuit (BOOSTXL-DRV8305)

Asif Ahmed
Expert 1570 points

Hello -

I have a question regarding the BOOSTXL-DRV8305 schematic (http://www.ti.com/lit/ug/slvuai8/slvuai8.pdf, ). Capacitors C4, C5, and C6 are 35V rated 5R capacitors with a 1uF value.

What is the function of these caps? I'm assuming these are decoupling capacitors, but I am seeking a bit more detail around their function. I am designing hardware based off this design. In my particular case, I have some space constraints. If I were to use lower-value capacitors (say, 0.47uF, or even lower) for C4, C5, and C6 ,would there be any negative effect?

One more small question. In the inverter portion of the above-mentioned schematic, there are yellow blocks labeled "NT1" through "NT12" - what are these?

Any insight is appreciated.

Best,

-asifjahmed

  • 0
    TI__Guru** 114905 points
    Hi Asef,

    C4, C5, and C6 are small ceramic capacitors that are placed near the top of each inverter phase. Please look at the location on the layout, which shows how close the capacitors are to the FETs. These capacitors (with low ESR) provide the initial current to the phase until the bulk capacitors (with higher ESR) can provide additional current.

    It depends on your system if smaller capacitors will have a negative effect. If the system current is less than half of the BOOSTXL-DRV8305, it may work. You can try various sizes once you have the system together as long as the footprint is the same.

    NT1 through NT12 are used to designate a "Net-Tie" in Altium. This allows connection of nets with different names with no design rule violations.