> If you drive an I/O pin to it's maximum *rated* current, say 25 milliamps > if I remember correctly, it should work all day. There is also a > specification on maximum output current for an entire port, which is also > a limitation. Also know and appreciate the effect that small variations in the process used to create the parts has on these parameters. Even if you happen to have one PIC that will supply 40mA with no problem, the next one you try may smoke at 26mA. For example I designed a circuit that used a 1.25V reference for the A/D converter (the datasheet says a minimum of 2V, but I overlooked it). I ordered PCBs and the first one I built worked perfectly. But numbers 2,3,4,5, AND 6 all failed. I drove myself crazy trying to track down the problem thinking how can it be a HW issue if all the boards are the same (thanks to the list for helping me find my error). But the truth is, especially when you are operating outside of the range of specs that have been tested by the manufacturer, no two boards/components are EVER the same. Also worth noting is that in my case these were all TQFP-44s that came one after the other from the same tape so one would think that they are as consistent as you will get (probably from the same batch, etc). I did a semester class making a wafer full of transistors, diodes, etc in the fab lab at U of I and believe me, every aspect of semiconductor manufacturing (as with any human endeavor) is imperfect. A few degrees too hot or cool here or an extra second or two there or a slight variation in gas flow or exposure time/intensity or acid concentration (... you get the point) somewhere in the process will change the characteristics of the device being made, and even the state of the art control systems that are used in the industry are obviously not perfect. And even if they were, the die for a PIC (as with virtually any component) is made on a large wafer that holds many copies of the die that are cut apart when the processing is complete. Then numerous wafers are processed together as a batch. There are spatial variations in conditions within a batch or even across a given wafer that can be significant. This is likely why I had PICs that presumably were from the same batch that showed such variation. While these variations are out of your control, at least if you are operating within spec with some safety margin you can pretty safely assume that parts will be the same at least to the degree that they are all within specified datasheet tolerances. My point is, even if a part will work out of spec, it is likely to cause so many debugging headaches and reliability problems down the road that it is best not to even think about it unless you have some particular reason to do otherwise. Nick > > > -- Lawrence Lile > > > > > > Omega Software > Sent by: pic microcontroller discussion list > 02/19/2004 05:19 AM > Please respond to pic microcontroller discussion list > > > To: PICLIST@MITVMA.MIT.EDU > cc: > Subject: [PIC]: can I safely short an I/O pin? > > > Hello, > can I safely source and sink all the current that the PIC I/O pin is > capable > of, even for hours, without fearing a possibility of damage to the chip? > > Thanks, > Andrea > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads