UCC27322 with pictures!!!

Notice the description at the bottom about PGND..."Grounds are separated to minimize ringing affects due to output switching...."

What does this mean? ... that we don't hook all grounds together or that we do our best to keep them as far apart as possible?
I have been assuming that I just keep them as far apart as possible, but the diagram doesn't look like it has a common ground.
I think I understand it... but I want to be sure.

I'm driving an FET (IRLB8743) with the UCC27322, am I correct in assuming that the same source can be used for the UCC27322 and the drain of the FET?

Thanks,

Rich
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Comments

  • 3 Comments sorted by Date Added Votes
  • Switching the chip "on," could cause PGND to raise slightly, due to IR losses in the trace leading to it. If AGND is connected to PGND at the chip, AGND would also rise, changing the switching threshold relative to logic ground of the input MOSFET. It's best to connect AGND directly to logic ground and PGND to power ground. These two grounds are then connected together at a single point near where both supplies enter the PCB. If your board has a ground plane, the two grounds should be isolated from each other by an insulating divider that terminates near where the two supplies come in.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • rjo__rjo__ Posts: 1,806
    Thanks Phil
  • rjo__rjo__ Posts: 1,806
    By the way... the ucc27322 has kind of amazing engineering. Through very simple mistakes on my part, I have managed to blow up three of them...
    all without injuring the P1's pins:)
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