I'm running the ADS1259 on a +5/Gnd supply, which allows me access to the +2.5 Internal Reference. Unfortunately this +2.5 reference is turned on/off by an internal register (which is of complete nuissance for my application unfortunately).
I am driving the ADS1259 with a Low-Noise Differential-Differential Amplifier. It has a a Common-Mode bias pin, which I supply with this +2.5 Internal Reference. Hence I take a +/- ground-referenced signal and center it Common-Mode at +2.5V, exactly mid-scale for the +5/Gnd ADC.
Unfortunately, on startup the Internal Register is not set to turn the Internal Reference on; hence the +/- signal is not centerred at +2.5V, and hence I cannot guarantee that it will fall within the AINN > (Avss-300mV). I do not want to damage the ADS1259 by exceeding the AINN constraint.
Is there a way to default-turn on the Internal Reference on startup? Or what is recommended to pull this up to ~2.5V on startup? I tried pulling it to 2.5 with a Resistor Divider(100K) from my +5 Supply, but it was not happy with this solution; I am unsure what the REFOUT pin does on startup (prior to programming the registers), and it is not some sort of open-collector/drain as it was fighting with my resistor divider. An external switch-network seems cumbersome and eliminates the point of having a stable Voltage Reference.