From the MAX11190 datasheet absolute max ratings, it says that OVDD max voltage rating is (VDD+0.3V) or 4V whichever is lower. Does this mean that VDD must be powered up before OVDD?
Not exactly. There is no sequencing requirement on VDD and OVDD; either can come up first, or they can both come up together. What is important is that both VDD and OVDD are within the defined limits (e.g. OVDD must be <= VDD+0.3V)
