>I've used the LT1637 as high-side current sensor amp with good success. One
>nice feature of it is that it can have its inputs above its supply. Does it
>have to be high-side? Low-side measurement is easier...
>
>What is the fiddling and twiddling you had to do with opamp designs? After
>all, in your application, the MAX472 is little more than an opamp. (It has
>that absolute value output feature, but in a 4-20 mA current loop the
>current direction is known.)

For high side current sense you may like to look at the Zetex ZXCT10xx rage 
of devices. Some are voltage output, some are current output. On the front 
page at http://www.zetex.com/ select the "current monitors" in the third 
menu on the list. Some of the devices are available through Farnell and RS. 

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