[SI-LIST] Re: Experience with Power supply collapse on boards due to excessive decoupling.

In no particular order:
(1) review stability requirements of power supply

If these are met, then I suggest a divide and conquer approach:
-  verifying power supply, POL supplies, and complete board separately.

(2) power board on with all passives, no silicon, and no load.
(3) apply resistive load.
(4) if there are multiple POL supplies on the board, deal with each separately.
(5) power the complete board with different power supply to cross check results

See previous SI posts re measuring power supply noise.

Regards

Jon Keeble


  ----- Original Message ----- 
  From: Vipul Badoni 
  To: si-list@xxxxxxxxxxxxx 
  Sent: Wednesday, November 26, 2008 9:18 AM
  Subject: [SI-LIST] Experience with Power supply collapse on boards due to 
excessive decoupling.


  Hello SI-Folks,
   

  I was wondering if some of you could share with me your experiences with
  power supply collapse due to excessive decoupling of only a few values
  of capacitor on boards drawing a lot of switching current. The situation
  I am dealing with has ~400 in number of 0.1uF caps and ~200 in number of
  1uf caps. The power supply shows a lot of noise ~400mV. 

   

  Regards,

  Vipul Badoni.

   


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