Other Parts Discussed in Thread: TPS549B22,
Can the PMBus pins on the TPS549B22 and TPS549D22 support a 1.8V I/O termination voltage for the pull-up resistors?
The TPS549B22 and TPS549D22's PMBus pins are designed to meet SMBus 3.1 "High Power" 1MHz class voltage and timing requirements.
This includes a Input Voltage "High" (VOH) maximum threadhold of 1.35V and Input Voltage "Low" (VIL) minimum of 0.8V in order to support 1.8V termination voltages and a maximum Output Voltage Low (VOL) of 0.4V with a 20mA pull-up.
The pull-up termination resistance should be sized to ensure the termination current with a 0.4V output is less than 20mA (no less than 70Ω) while ensuring a low enough rise-time to rise from 0V to 1.35V within the timing constraints of the bus-speed used and the total bus capacitance.