At 09:06 AM 1/22/2002 -0800, Brad Velander wrote:
>Juha,
>Have you
>considered doing your resistance as a short section of PCB trace? For
>example a 0.020" wide trace, 1 oz CU, of 0.161 inches in length will give
>you a resistance of 0.00399 ohms according to some calculators. This length
>would probably need to be tweaked according to you PCB specs and the
>fabricators typical tolerances. A lot of current sense devices have
>application notes which suggest using specific lengths of traces for your
>sense circuit.

One might be able to design something trimmable if more accuracy than the 
+/- 20% or so that I'd expect from normal fab tolerances were necessary. 
I'd think of a series of vias that could be drilled out, or shorted 
together with soldered wire jumpers. Of course, there is also temperature 
coefficient to be considered....


[EMAIL PROTECTED]
Abdulrahman Lomax
Easthampton, Massachusetts USA

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