Article View: sci.electronics
Article #11081Re: Can despiking caps be connected to a central ground?
From: Bob Myers
Date: Thu, 08 Oct 1992 17:06
Date: Thu, 08 Oct 1992 17:06
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> The answer is THEY must go between VCC and GROUND on the SAME
> chip. The reason for a despiking cap is the momentary
> current rush caused by switching in DRAMs and some other
> chips. The cap supplies the current needing for these chips
> and prevents them from degrading the powersupply. By
> placeing them not Immediatly to the chips ground you are
> totally defeating thier purpose.
>
No, they do NOT need to go on the same IC if that means longer cap leads
than simply tying to the nearest ground point. Assuming a board with
power/ground planes, or a power/ground "grid" as Henry mentioned (easily
"do-able" on a wire-wrap board, this may mean that the caps tie to power and
ground *between* adjacent ICs. Distributing the capacitance across the
power plane is the key, not tying the caps to a given chip.
Bob Myers KC0EW Hewlett-Packard Co. |Opinions expressed here are not
User Interface Tech. Div.|those of my employer or any other
myers@fc.hp.com Fort Collins, Colorado |sentient life-form on this planet.
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From: myers@hpfcso.FC.HP.COM (Bob Myers) Date: Thu, 8 Oct 1992 17:06:05 GMT Subject: Re: Can despiking caps be connected to a central ground? Message-ID: <7480126@hpfcso.FC.HP.COM> Organization: Hewlett-Packard, Fort Collins, CO, USA Path: arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!sdd.hp.com!scd.hp.com!hplextra!hpfcso!myers Newsgroups: sci.electronics References: <jeremym.718096983@sfu.ca> Lines: 20