Hi,

I am trying to convert a current measurement to voltage using a 75mv 30A Current shunt.

The problem is that I need a measurement from
-30A to +30A within the range of 0..5v.
i.e. -30A = 0v, 0A = 2.5v, 30A = 5v.

Is this possible by using opamp(s) on a single supply of 0..14v?

your help would be greatly appreciated!

Regards,
Kevin Bloch

 

Hi
I used the RMS to DC (636) chip. It only needs afew external components: +/- 15V, etc

"http://dbserv.maxim-ic.com/quick_view2.cfm?qv_pk=1197":http://dbserv.maxim-ic.com/quick_view2.cfm?qv_pk=1197 is a link to the data sheet.
Later
zan

 

Not easily, but it can be done if the current shunt is on the high side. For example, one side of current shunt is at 14V the other will range from + 13.925 to +14.075. If you have a 2:1 voltage divider on each to ground you now have signals well within the common mode voltage range of a single supply opamp. You would then refer the input to + 37.5mv with precision reference and set gain to obtain 5V.
You could calculate the dividers to provide the offset but this would introduce an error term when the voltage wasn't 14.00.

Regards

cww
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I suggest you Purchase a off the shelf signal isolator. This will give the advantage of isolation and ease of obtaining spares.

Signal Isolators can be obtained with selctable input and output ranges.

Just remember that a seperate supply for the signal isolator will be required.