we are playing the gain control of an AD9117 DAC.
Config: VDD is 3.3V, Vref is 1V, IRSET is enabled and we have IV converter with 49.9 ohm resistors at the DAC outputs. CMPLx grounded, RLxP/N open.
Stated in datasheet rev. E p.38:
Changes the value of the on-chip IRSET resistor; this scales the full-scale current of the DAC in ~0.25 dB steps twos complement (nonlinear), see Figure 99.
000000 (default): IRSET = 2 kΩ.
011111: IRSET = 8 kΩ.
100000: IRSET = 1.6 kΩ.
111111: IRSET = 2 kΩ.
Q1: How is it possible to have same IRSET values (2k) with different register codes (000000, 111111)? They seem one step far, so the resistance must be differ.
Q2: If IRSET equals 2k then the IOUTFS shouldn't be 32*Vref/2k = 16mA (as per page 45)? Figure 99. looks different.
Q3. Where is the tolerance of xRSET? (I didn't find it on the datasheet.)