The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: Paul Burke
Subject: Re: incredible comparator behaviour
Date: Thu, 09 Jan 2003 08:51:28 +0000
Organization: Scazon Systems
NNTP-Posting-Host: host213-120-44-227.webport.bt.net (18.104.22.168)
X-Mailer: Mozilla 4.7 [en] (Win98; I)
> I try use a MAX942 comparator. this is a dual fast comparator with internal
> Normally a simple to use device.
They are VERY fast and incredibly sensitive to parasitic feedback. It's
easier to make them oscillate than to operate properly, despite the
> But I encounter strange problems.
> I want to detect (at IN- pin) pulses of 1.2V High and about 100ns wide (rise
> time about 15-20ns).
> But when I fix a threshold of 1.4V at IN+, the device is switching and I
> have a pulse at the output.
> The height of the pulse is decreasing when I rise the threshold.
You have noise somewhere- either power rails, reference or signal. It
could also be feeding through from the other comparator in the package.
What is the impedance of the signal lines? I have found this needs to be
very low, or the line picks up wisps of RF and the output yammers away.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup