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Additional VDD/Vss pins on QFP packages of Propeller — Parallax Forums

Additional VDD/Vss pins on QFP packages of Propeller

octaloctal Posts: 67
edited 2010-12-10 15:41 in Propeller 1
Hello,
on the QFP version of the Propeller chip, there are additional VDD/Vss pins.
When I make a PCB for this version of the chip, have I to connect ALL VDD (respectively Vss) pins to power lines (ground resp)?
Also, have I to add decoupling capacitors to them? (even if they are NOT connected) ?

Regards

Comments

  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-12-10 06:11
    As this question always gets answered, YES and YES.

    The different pins allow the internal silicon to get its power without excessive cross flowing. Internal damage to the PLL circuits have been reported when all the pins are not connected up and decoupled properly. Most people put higher value, 47-100uF, tantalum caps as near to the chip as possible
  • SapiehaSapieha Posts: 2,964
    edited 2010-12-10 06:39
    Hi octal.

    As Toby said all 4 pairs need be connected and have 100nF decoupling capacitors. To that as He said at last pair nearest Crystal will have One bulk 33-100uF capacitor parallel with decoupling capacitor.
    Place that capacitors as near pins as possible. BEST case 4 Bulk capacitors parallel with decoupling ones. In that case 10-33uF.
  • octaloctal Posts: 67
    edited 2010-12-10 15:41
    Thank you very much for these details. I never used the QFP version and I wanted to be sure.

    Best regards
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