Muhammad Abu Bakar Posted June 27, 2006 Report Share Posted June 27, 2006 Hello!Does some one know why the supply pins in digital IC's are at corner while most OP-amps have them isomewhere in middle of the chip. Is it only due to mechanical construction?Regards! Quote Link to comment Share on other sites More sharing options...
ZomBiE Posted July 3, 2006 Report Share Posted July 3, 2006 Many manufacturers have gone to a compromise with their designs ages ago with themselfs for compatibility... All the chips can't be the same for design broblems, etc... Quote Link to comment Share on other sites More sharing options...
Theatronics Posted July 12, 2006 Report Share Posted July 12, 2006 The old Standard was to place the digital power pins in the corners of the chips.in the 70s this made board layout a bit easier. Power buses ran between the chips in rows and they were much larger traces than the digital signals that could sneak in and out between the pins. Analogue chips didn't live in a world of straight rows and data busses. The pin placement was driven by design needs. Some parts were designed as direct replacements of older parts. Other parts had pin layouts based on expected use. For instance, if possible, two related pins might be placed near each other to simplify PCB layout.There are a few industry standards but they are not rules, just traditions. Just like most people like to mount through hole parts all on one side of the PCB and call it the top. If a part doesn't fit one way, why not try mounting it from the bottom? Presto, a reverse pinout!-Mike Quote Link to comment Share on other sites More sharing options...
indulis Posted July 12, 2006 Report Share Posted July 12, 2006 More often than not, it's a matter of convienience when connecting the die to the carrier. You don't want the bonding wires running all over the place. Quote Link to comment Share on other sites More sharing options...
Muhammad Abu Bakar Posted July 14, 2006 Author Report Share Posted July 14, 2006 Hello MikeJust like most people like to mount through hole parts all on one side of the PCB and call it the top. If a part doesn't fit one way, why not try mounting it from the bottom? Presto, a reverse pinout!I realy do so. Once I had PCB's printed from wrong side(acutually flipped). Then I had to solder DIPs at the bottom side. However I got ZIPs on top side with moving the legs at opposite sides.About the matter of IC pins I personally feel:1. All i/p pins should be grouped togather (Mechanicaly in a row).2. All o/p pins should be grouped togather.3. Power supply pins should be neighbours.4. The pins performing control functions should come in line.Perhaps it might put PCB designers on a Holiday ;D Quote Link to comment Share on other sites More sharing options...
Theatronics Posted July 14, 2006 Report Share Posted July 14, 2006 Yes, that would make it easier in many cases. :)Once in a while I have looked at a chip's pinout and wonderedwhat the designer was thinking when they made the part. ??? Lateras I started to design a board layout I found that some of the pinplacements were rather clever. :DWhen working with a new chip with an odd pin out I try to find aexample PCB layout from the manufacturer. These can sometimeshint at why some designs were selected. ;)-Mike Quote Link to comment Share on other sites More sharing options...
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