windoze killa
- Mar 4, 2006
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DRC checks for errors that have been made generally caused by manual routing. Automatic routing will normally only come up with errors when it fails to route a track. When you manually route you may use an incorrect track width or clearances maybe to small. When DRC is run it will generate a report and from this report you can correct the errors.
Yes, "errors" can occur, and happen often with manual routing, but it's the user that defines and sets up the "rules" for DRC.....
Different rules can apply for similar situations... for example:
A PCB with a .25" hole in it. If you have the hole drilled, the accuracy of the center location is typically +/- .01", but a machined holes center accuracy is +/- .005". So DRC clearances from the hole to copper or board edge would be different. Another example would be copper weight.... with 3oz copper minimum trace width is 8 mils with 8 mil spacing. With 1oz copper I believe that number goes down to 4mils.
As a side note... auto routing isn't used very often in analog design, it's more of a digital thing.
Different rules can apply for similar situations... for example:
A PCB with a .25" hole in it. If you have the hole drilled, the accuracy of the center location is typically +/- .01", but a machined holes center accuracy is +/- .005". So DRC clearances from the hole to copper or board edge would be different. Another example would be copper weight.... with 3oz copper minimum trace width is 8 mils with 8 mil spacing. With 1oz copper I believe that number goes down to 4mils.
As a side note... auto routing isn't used very often in analog design, it's more of a digital thing.
Are you kidding? I ALWAYS use auto-router. Analog, Digital, and Mixed-Design. You must not put together very complicated circuits if you manual route all of your Analog boards. ERC and DRC eliminate any problems that you might encounter. Netlist tells you if anything is missing. If there ever IS a problem, the few traces you might go back and re-run are much less time consuming than manual routing an entire board design. If I ever caught one of my Engineers manual routing an entire board layout, he would be looking for another job. That's MY time wasted.indulis said:
MP
I've been designing DC-DC converters for the past 15 years (but I do go back to the days of tape and doughnuts).... if ANY of our CAD designers tried to auto-route one, then they would be looking for work!!
Yeah..... I suppose it's industry dependent, and that there are low frequency, low power designs that could get away with auto-route, but DC- DC converters DO NOT, UNDER ANY CIRCUMSTANCES fall into that category!!!!! We were using P-CAD, but have now switched to PADS. All the designs are "intelligent", so net list issues are never a problem and DRC's are layer dependent. A typical 150W quarter brick design is 14 to 16 layers, 3 oz copper on power layers, 2oz CU for signal layers and just about all of them use planar magnetics. As the power densities increase, proximity affects have to be considered more and more... one of the designs I'm currently working on is a 650KHz 1/4 brick, push-pull, current doubler, 1.5V @ 40A SMPS. You just can't put the feedback next to the output traces, it would be suicide..... those have to be guarded and shielded runs!!!! All the power loops HAVE TO BE layed out first..... all the "other stuff" goes into the space leftover. I am not aware of any auto-router that can handle "power design".
Yeah..... I suppose it's industry dependent, and that there are low frequency, low power designs that could get away with auto-route, but DC- DC converters DO NOT, UNDER ANY CIRCUMSTANCES fall into that category!!!!! We were using P-CAD, but have now switched to PADS. All the designs are "intelligent", so net list issues are never a problem and DRC's are layer dependent. A typical 150W quarter brick design is 14 to 16 layers, 3 oz copper on power layers, 2oz CU for signal layers and just about all of them use planar magnetics. As the power densities increase, proximity affects have to be considered more and more... one of the designs I'm currently working on is a 650KHz 1/4 brick, push-pull, current doubler, 1.5V @ 40A SMPS. You just can't put the feedback next to the output traces, it would be suicide..... those have to be guarded and shielded runs!!!! All the power loops HAVE TO BE layed out first..... all the "other stuff" goes into the space leftover. I am not aware of any auto-router that can handle "power design".
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windoze killa
- Mar 4, 2006
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I agree totally. I could never imagine manually routing the 4 layer processor boards we design. We do some manual cleaning up at the end but it would take us months. There is also a heap of analog stuff on these boards too. The power of programs like Altium DXP make it soooooo easy. Just have to make sure your schematic and your design rules are correct and away you go.MP said:
Yes, but your talking digital. Digital is a different story... yes, it'll work there. I was talking power analog design.
Do you mean this software!!!
http://www.cheap-software-megastore.com/index.php?target=desc&progid=1329
Do you mean this software!!!
http://www.cheap-software-megastore.com/index.php?target=desc&progid=1329
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windoze killa
- Mar 4, 2006
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The board we just finished has 4 DC-DC SMPS on it for powering the the various components. It also has built in GPS and radio modems. It also has 7 analog inputs with filtering. I am not sure why power analog design would be any different. If you are talking RF power then yes, you may need to do a little bit of manual routing but you initial statement refered to DC-DC convertors.indulis said:
Yes I did, and yes it is!!!! Those that know, know and those that don't, don't!!!
The package is PADS (more than adaquate)... I don't do the layout's, the CAD designers do it with my guidance... I'm a circuit designer, not a PCB designer.
Just in case.... I'm NOT talking about the auto-routers ability to connect all points in a node!!! I am talking about how it routes those connections. The exact path that the etch follows. The router that can take into account induced pickup due to a high field strength flux fields doesn't exist. In fact a "good" analog simulator for power analog dosn't exist, so forget about layout tools!!!
Consider the subject closed!!!
The package is PADS (more than adaquate)... I don't do the layout's, the CAD designers do it with my guidance... I'm a circuit designer, not a PCB designer.
Just in case.... I'm NOT talking about the auto-routers ability to connect all points in a node!!! I am talking about how it routes those connections. The exact path that the etch follows. The router that can take into account induced pickup due to a high field strength flux fields doesn't exist. In fact a "good" analog simulator for power analog dosn't exist, so forget about layout tools!!!
Consider the subject closed!!!
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