The SO output is a push-pull structure, as indicated in the electrical characteristics table of the datasheet:
Output High Voltage - VOH = VCC - 0.4V, @ IOUT = -1.6mA
Output Low Voltage - VOL = 0.4 V, @ IOUT = 1.6mA
MAX31855
Production
The MAX31855 performs cold-junction compensation and digitizes the signal from a K-, J-, N-, T-, S-, R-, or E-type thermocouple. The data is output in...
Datasheet
MAX31855 on Analog.com