query about a product

query about a product

Postby Ronan Keets » Fri Sep 18, 2015 7:58 am

hello all ,

I am trying to replicate the PCB design shown as an image in the below link. I have looked at the device datasheet and understand the device itself fairly well. However I have never done any high power PCBs before and needed to know are there any special things that I have to account for when designing PCB that can handle 10A or so currents. I read something about impedance controlled PCBs etc, do I need those for this? Also where can I get such PCBs made in the US, at a lower cost.
http://www.ensembletech.in/portfolio-items/prototyping-dual-h-bridge-drive-for-under-water-rov/
Ronan Keets
 
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Joined: Fri May 22, 2015 10:32 am

Re: query about a product

Postby edsimmons3 » Fri Sep 18, 2015 8:12 am

Hi Ronan,

No you don't need impedance controlled PCBs, these are normally used for extremely high frequency designs such as radio and high bandwidth digital data.

Obviously you need to be careful of the trace widths, try to use a very solid ground plane to aid in heat dissipation. Keep inductive loops to a minimum otherwise you'll radiate a lot of switching noise at high currents...

Thicker copper on the PCB comes at a price and it's best to see if you can get the performance you're after with the standard PCB specs before moving on to thicker copper if needed, since the thicker copper carries some penalties in the process that limit the resolution of your design, but you're unlikely to need it in the 10-30A region, just wide traces.

We have a couple of PCBs that routinely handle 50A @ 12v for sustained periods, sure the PCB gets warm with that load, but doesn't heat up nearly as much as the MOSFETs ;)

Nick DeSmith's calculator is helpful... http://www.desmith.net/NMdS/Electronics/TraceWidth.html

Have fun,
Ed
edsimmons3
 
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Re: query about a product

Postby Ronan Keets » Sat Sep 19, 2015 11:38 am

thanks edsimmons3 will look to it ... :)
Ronan Keets
 
Posts: 2
Joined: Fri May 22, 2015 10:32 am


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