I'd like to use SC16IS750 to bridge I2C to UART. Therefore I would like to use IRQ functionality to prevent software from the requirement to poll for status. For the physical connection in datasheet is mentioned, to use 1k pull-up for 3V3 or 1k5 for 2V5 supply. Would it be possible to use 100k connected to 1V8 power supply as well? The point is, that I have some host device which hs just 1V8 compatible pins and I'd like to prevent some additional level shifters.
I'm just wondering about pull-up resistor value requirement as based on datasheet, IRQ pin is able to sink up to 4mA, why does pull-up resistor for 2V5 be higher than connected to 3V3?