Until recently I've been using

http://www.maxim-ic.com/appnotes.cfm/appnote_number/823

with 4-20mA sensors, and it works very very well, on a DMM as
well as down to the resolution of a PIC A2D. No fiddling or twiddling
needed, unlike the op-amp designs I tried

Unfortunately a new design means a revamp, and the MAX472 is
not recommended for new designs. Sigh

The client found the RCV420

http://focus.ti.com/docs/prod/folders/print/rcv420.html

but it's relatively expensive (from where I can get them)

I found this, the INA138 - (231kB)

http://focus.ti.com/lit/ds/symlink/ina138.pdf

It looks similar, a little simpler even, but nowhere in the ANs does
it say suitable for 4-20mA. It seems to me it could do it

Googling around finds several devices, just wondering whether
anyone has a proven cheap accurate method for 4-20mA before
I go ordering parts

TIA

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