Help with AD694 0-10V to 4-20mA V-I Convertor

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megaposiedon

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Hi guys,

I have an application that requires a 4-20mA signal to drive a ItoP convertor that in turn drives a control valve.. I'm using Nation Instrument's Compact Field Point AIO610 which has only voltage output of range 0-10.2 Volts.

Therefore I require a V to I Convertor to converter that converts 0-10V to corresponding 4-20mA. For this I'm using an IC - AD694 (Analog Devices) which is a precision V-I Convertor.

AD694 Datasheet

So, here come the major problem. I used this IC and I'm getting 4mA for 0 volts but when I change the input voltage..The output current remains constant. Following are my connections

Pin 1 and Pin 2 Short
Pin 3 - Voltage IN
Pin 13 - 12V DC Supply
Pin 11 - Current Out
Pin 5 and Pin 9 Short

I followed Figure 2 give in the data sheet for the connections. Though with unexpected output..

What really intrigues me is the Pin 7. Should I supply a 10V to that Pin ?? or short it with Pin 8..

I didnt find any other interfacing circuits on the internet. Can anyone figure out what went wrong with the connections ??

I would be very much thankful

Cheers
Posiedon
 
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