Date: Wed, 30 Jul 1997 09:05:47 GMT From: mouth@ibm.net (John Kelly) To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: msmith@atrad.adelaide.edu.au, freebsd@atipa.com, hackers@FreeBSD.ORG, terry@lambert.org Subject: Re: Sharing interrupts Message-ID: <33e90332.41786720@smtp-gw01.ny.us.ibm.net> In-Reply-To: <199707300848.SAA21116@genesis.atrad.adelaide.edu.au> References: <199707300848.SAA21116@genesis.atrad.adelaide.edu.au>
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On Wed, 30 Jul 1997 18:18:14 +0930 (CST), you wrote: >I would avoid the use of silicon power diodes for this application; >they have a significant parasitic capacitance, and will generate a >substantial spike on the ICU input when your device signals an >interrupt. They also have a long Toff (turnoff time), meaning that >when your device drives the interrupt output low you will generate >another spike and considerable ground noise. They also have a very >_substantial_ voltage drop at low current, certainly not "minimal". > >If you must use a large diode, use a "fast-recovery" type such as a >UF4001; ideally, you should be using a fast small-signal diode like >the (very cheap) BAT-47. This device also has a much lower Vf(max), >around 0.4V, and very low parasitic capacitance. More interesting points. Thanks for the heads-up. John
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