From the typical application circuit, the frequency of the recommended resistor capacitor network is 15kHz.
MAX31865
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The MAX31865 is an easy-to-use resistance-to-digital converter optimized for platinum resistance temperature detectors (RTDs). An external resistor sets...
Datasheet
MAX31865 on Analog.com
From the typical application circuit, the frequency of the recommended resistor capacitor network is 15kHz.