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AD5755 offset cannot go below minimum value?

Question asked by tcachat on Feb 7, 2012
Latest reply on Oct 24, 2014 by JerryS

We have designed and assemble a board with an AD5755ACPZ. Without any calibration, in 4-20mA current output mode we measure 4.015 mA to 20.015 mA, with 0x0000 to 0xFFFF in the data register. It is easy to compensate by software to obtain 20.000mA, but it seems difficult to go below 4.015 mA. I have tried to use the offset register, but I could only make the maximum (20.015mA) lower, not the minimum. I seems to me that the offset is numerically added to the data register, as explained in Figure 76 page 39 of the datasheet. If the data register is 0x0000, is it possible to go "below" zero?

 

I do not agree with http://ez.analog.com/message/41185#41185

 

Thank you in advance

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