So I am trying to interface a slave device to a master uC through an ADUM4151 SPI Isolator and am getting confused on where I need pullups for the MISO line as I see it a few ways in reference designs.
My slave device's MISO is open drain, so he needs a 5k pullup. I'm then putting him through the ADUM4151 and straight to my uC (through 100ohm resistor). I don't have any other slaves on the bus so I figure this should be the end of it. However, I see a few designs where a schottky diode is placed with its cathode facing the output on the isolated/uC side of the isolator and then another pullup before going to the uC.
Can anyone explain to me what the point of that would be? I've read a few things stating it "converts the isolators push-pull output to open drain." But seems like I'm going to be sending current into an output pin through the diode when MISO is pulled low. I figure it'd only be useful with other slaves on the processor side of the isolation so I probably don't need it, but would like to understand the point/purpose.