The AD5628BCPZ datasheet is a bit confusing.
There is only one pin (#6) nammed Vrefin/Vrefout. The datasheet (page 21) states that when the internal reference is on, its voltage is available at pin #6 (cause an decoupling cap is advised). And table 2 states an output impedance of 7.5k. However, this not shown on figure 55.
I wonder how the internal circuit works, given that the voltage on pin #6 is either 2.5V (internal) or 5V (external).
Does that mean that, if I want to use either the internal reference (2.5 V) or an external reference (0 to 5V, multiplying), depending on cases, I absolutely need an additionnal (external) switch to dis/connect my own 0-5V reference from pin #6 (while turning the reference on/off accordingly through register DB0) ?