- Mon Nov 15, 2010 5:23 pm
#113527
Hi Everyone,
I am still very new to all of this. I'm trying to include the LM2575 switching regulator (TO-220 case) on my board. I found a part in the ads4 library called LM2991 which has the TO-220 case, so I copied it over to my library and created the LM2575 symbol and device. The problem is that when I add it, the pads in the board layout are automatically expanded such that they overlap. I determined that this is because the SparkFun DRU file has a 12mil min for pads in the 'restring' tab. It also has a '25% of drill hole' rule. Since the TO-200 violates both of these, the pads are automatically being expanded. However, they then violate the clearance/overlap rule.
How would you recommend proceeding? It seems really risky to change the DRU 12mil min AND the 25% min to smaller values because there are other components on my board with pads which are currently being expanded by these rules (these just don't violate the clearance rule and are therefore have not been a problem). I would hate to shrink all of those pads just to make the TO-220 work. I can't redesign the TO-220 because if I make the pads large enough to not violate the DRU minimums, they will then violate the DRU overlap rules. Should I just not be using the TO-220?
Thanks!
Josh
I am still very new to all of this. I'm trying to include the LM2575 switching regulator (TO-220 case) on my board. I found a part in the ads4 library called LM2991 which has the TO-220 case, so I copied it over to my library and created the LM2575 symbol and device. The problem is that when I add it, the pads in the board layout are automatically expanded such that they overlap. I determined that this is because the SparkFun DRU file has a 12mil min for pads in the 'restring' tab. It also has a '25% of drill hole' rule. Since the TO-200 violates both of these, the pads are automatically being expanded. However, they then violate the clearance/overlap rule.
How would you recommend proceeding? It seems really risky to change the DRU 12mil min AND the 25% min to smaller values because there are other components on my board with pads which are currently being expanded by these rules (these just don't violate the clearance rule and are therefore have not been a problem). I would hate to shrink all of those pads just to make the TO-220 work. I can't redesign the TO-220 because if I make the pads large enough to not violate the DRU minimums, they will then violate the DRU overlap rules. Should I just not be using the TO-220?
Thanks!
Josh
