Thanks Spehro. That's just what I needed. >From: Spehro Pefhany >Reply-To: pic microcontroller discussion list >To: PICLIST@MITVMA.MIT.EDU >Subject: Re: [EE]: Pull-up values for 74165? >Date: Tue, 24 Jun 2003 17:46:50 -0400 > >At 03:04 PM 6/24/2003 -0600, you wrote: >>Hi, >> >>I need to connect a DIP switch to a 74165 (to be precice, an SN74HC165N). >>I >>know I'm going to need pull-up or pull-down resistors here, but I don't >>know >>what value of resistors. >> >>10K? 100K? 1M? > >I tend to use 10K or even 4K7 for pullups, but I tend to deal with high-EMI >environments, often mains powered. If the circuit is battery powered, 100K >or >higher might be called for (check the leakage specs on the chip and make >sure >it's guaranteed to really pull it up to a 1 over temperature). > >>Are there trade offs in using higher or lower values? > >Lower values => more power consumption on closed switches, better noise >immunity >on open ones. > >Higher values => less power consumption, less noise immunity, leakage may >cause problems in extreme cases. > >Note that leakage isn't typically a practical problem at room >temperature, but I follow the data sheet guaranteed limits for >production designs. > >Best regards, > >Spehro Pefhany --"it's the network..." "The Journey is the >reward" >speff@interlog.com Info for manufacturers: >http://www.trexon.com >Embedded software/hardware/analog Info for designers: >http://www.speff.com > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listserv@mitvma.mit.edu with SET PICList DIGEST in the body _________________________________________________________________ Protect your PC - get McAfee.com VirusScan Online http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963 -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics