What is the tempco of the digital potentiometer?
There are two components that make up the resistance at any given setting. They are the poly silicon resistors (step resistor Rs) and the CMOS switch resistor (Rsw=50 Ω at 5V supply). Together they add up such that RWB = RS + RW, RS = RAB / 2N * D, where D is the decimal code. The tempco of the step resistor, which is published in the datasheet, is typically in the range of a few tens of ppm/°C for thin film or a few hundred ppm/°C for poly. The resistance of the switch, on the other hand, doubles in 100°C. As a result, the overall tempco is nonlinear and it is worse off at low value codes where the switch resistance dominates. Users should refer to the tempco graphs in the datasheets for more detailed information.
