From: Martin Griffith
Subject: Re: What resets the motherboard?
Date: Fri, 8 Nov 2002 17:41:33 +0000 (UTC)
Organization: BT Openworld
NNTP-Posting-Date: Fri, 8 Nov 2002 17:41:33 +0000 (UTC)
X-Newsreader: Forte Free Agent 1.92/32.572
On Fri, 08 Nov 2002 11:48:49 -0500, A E
>Before I start reading up on every chipset out there, what circuit is
>responsible for power up reset on a PC? In the good old days of the C64,
>there was a 556 monostable that generated a ~1 second reset pulse on
>power up or reset.
>More and more people, myself included, are having strange intermittent
>reset failures in that the PC doesn't go past the memory self test, but
>a hard reset gets it going again.
>Yes, I've seen the designs with the relay that closes the reset switch
>longer, I'm not interested in that.
>There has to be a simple explanation. I don't know about the power
>supply theory, since there isn't much in my PC, yet it still has the
>Could a simple cap be drifting and changing a RC time constant
>Anyways, I guess in the meantime I'll research chipset datasheets.
have a search for
on the Intel site, this is a couple of years old, but should be
from the pdf........
This document provides design suggestions and reference specifications
for a family of
power supplies that comply with the ATX Specification, Version 2.03 *
and chassis. It includes supplementary information not expressly
detailed in the ATX
Specification, such as information about the physical form factor of
the power supply,
cooling requirements, connector configuration, and pertinent
electrical and signal timing
This document is provided as a convenience only and is not intended to
replace the userís
independent design and validation activity. It should not be inferred
that all ATX or
ATX12V power supplies must conform exactly to the content of this
are the design specifics described herein intended to support all
configurations, because system power supply needs vary widely
depending on factors such
as the application (that is, for desktop, workstation, or server),
environment (temperature, line voltage), or motherboard power
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