We are setting AD9716 Full-scale Current as following: enable the internal on-chip 16k ohm Rset; Vref=1V; by which we can get a full-scale current=32* Vref/ Rset=2mA. While by test we found the current is only 1.6mA instead of 2mA. Is this error caused by the big tolerance of internal 16k ohm Rset? How accurate is this Rset and how accurate current we can get by this way?
Anyone can help on this case?
We connect the IoutP/N to a 250ohm load and see the DC voltage difference. We change the code from FFF to 000; but the FS currrent calulating from the voltage swing is only around 1.6mA not 2mA.
As discussed offline, the tolerance of IRset and QRset is about 20% which is why we describe how to adjust this resistance via SPI registers (0x04 and 0x07). If you run out of adjustment room by this method then Vref must be altered.