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QFP Chip — Parallax Forums

QFP Chip

NewzedNewzed Posts: 2,503
edited 2006-11-26 05:25 in Propeller 1
On the QFP chip, is it necessary to tie all the Vss and Vdd pins together or are they tied together internally?

Thanks

Sid



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Sid Weaver
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Newzed@aol.com
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Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2006-11-26 01:52
    They're tied together internally, but good circuit layout principles dictate that you also connect them externally, as well as bypass at least two Vdd/Gnd pairs.

    -Phil
  • James LongJames Long Posts: 1,181
    edited 2006-11-26 04:56
    Phil said...
    They're tied together internally, but good circuit layout principles dictate that you also connect them externally, as well as bypass at least two Vdd/Gnd pairs.

    -Phil
    Hmmm....is the bypass the filter cap?

    Educate me.

    Thanks,

    James L
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2006-11-26 05:14
    James,

    No, filter caps are typically at least 10uF and located near the regulator. Bypass caps are more like 0.1 - 0.2uF and located near each IC being powered. Both are necessary in a good design.

    -Phil
  • James LongJames Long Posts: 1,181
    edited 2006-11-26 05:25
    Phil....

    My terminology sucks.....so yea...that is what I meant.

    But thanks for expanding my vocabulary. burger.gif

    James L
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