David_
Advanced Member level 2
Hello.
I am developing a circuit to pass a maximum of 40A but when I use a **broken link removed** I find that even if I where to allow the temperature of the trace to rise to 100°C then I cannot pass such currents.
But that calculator has to be defective since if I input a 10mm trace width, 1 oz trace thickness, 60°C temperature rise, 25°C ambient temperature and 30mm trace length it says that the maximum current is 31,8A and a temperature of 85°C.
But if I raise the temperature rise allowed to 75°C(instead of 60°C) then the results become 27,9A @ 100°C...!
That is simply impossible isn't it, assuming all other parameters to be the same how could allowing a higher temperature result in a lower current?
Although it is true that in my application the current isn't continuous but I have had this situation before and I don't know what to do.
I can't get 2 oz copper boards, so I ether have to use vias to connect both top and bottom layer(this is a 4 layer design) in parallel or use layer 1 and 2(top and the one under it) or cover the top layer trace with solder, or put a thick solid copper wire of 2mm diameter on top of the layer and then solder it to the layer.
Non of which is options I thought that I would need to use, but a 10mm wide trace is already almost unviable to fit onto the PCB because the pads aren't made to connect to such wide traces.
What would you do?
Keep in mind that one of these traces to be carrying max 40A is the switch node of a non-isolated DC-DC converter, and although I don't now I think it sounds as one of those big layout mistakes to route the switching node to both sides of a PCB?
30mm trace length is longer than it will be but according to that calculator the trace length doesn't impact the current carrying capacity.
But the traces to be carrying that current is the ones from the battery connections all the way to the output wich shouldn't be much more than a low number of cm, 10cm worst case.
Though I do know that this calculator as well as all other such calculators are only rough estimations and depending on which standard they use the take different things into account and the results of calculators using the older standard is supposedly much more inaccurate than ones using the newest.
Any advice would be greatly appreciated.
Regards
I am developing a circuit to pass a maximum of 40A but when I use a **broken link removed** I find that even if I where to allow the temperature of the trace to rise to 100°C then I cannot pass such currents.
But that calculator has to be defective since if I input a 10mm trace width, 1 oz trace thickness, 60°C temperature rise, 25°C ambient temperature and 30mm trace length it says that the maximum current is 31,8A and a temperature of 85°C.
But if I raise the temperature rise allowed to 75°C(instead of 60°C) then the results become 27,9A @ 100°C...!
That is simply impossible isn't it, assuming all other parameters to be the same how could allowing a higher temperature result in a lower current?
Although it is true that in my application the current isn't continuous but I have had this situation before and I don't know what to do.
I can't get 2 oz copper boards, so I ether have to use vias to connect both top and bottom layer(this is a 4 layer design) in parallel or use layer 1 and 2(top and the one under it) or cover the top layer trace with solder, or put a thick solid copper wire of 2mm diameter on top of the layer and then solder it to the layer.
Non of which is options I thought that I would need to use, but a 10mm wide trace is already almost unviable to fit onto the PCB because the pads aren't made to connect to such wide traces.
What would you do?
Keep in mind that one of these traces to be carrying max 40A is the switch node of a non-isolated DC-DC converter, and although I don't now I think it sounds as one of those big layout mistakes to route the switching node to both sides of a PCB?
30mm trace length is longer than it will be but according to that calculator the trace length doesn't impact the current carrying capacity.
But the traces to be carrying that current is the ones from the battery connections all the way to the output wich shouldn't be much more than a low number of cm, 10cm worst case.
Though I do know that this calculator as well as all other such calculators are only rough estimations and depending on which standard they use the take different things into account and the results of calculators using the older standard is supposedly much more inaccurate than ones using the newest.
Any advice would be greatly appreciated.
Regards