The PCA9512A datasheet includes the following note:
(1) Can someone confirm that the pull-up resistor voltage need not match the supply voltage without enabling the acceleration function? Specifically, is there a hazard in using 2.5V pull-ups with a PCA9512A device powered by 3.3V?
My application has an 2.5V I2C master (whose input may not exceed 3.05V (VDDIO + 0.550V). The PCA9512 has a VCC spec of 2.7V minimum. I experimented with a PCA9515 legally powered at 2.5V, but there's an fixed-offset component (a PCA9615B) downstream that can't propagate the bus. I could create a tiny 2.7V or 3.0V supply; but would prefer not, unless absolutely necessary. Assuming the scenario works as I'd like-- I'd have a pair of pull-up resistors to 2.5V on the primary side of the PCA9512A with VCC = 3.3V; while the secondary side has, in two instances 3.3V pullups with VCC2=3.3V, and in a third, 5V pull-ups with VCC2 = 5V.
(2) Of lesser importance, I'd like to understand what the hazard is in enabling the accelerator in this scenario. Has no bearing on my application; just intellectual curiosity.
Thanks very much in advance!