From the MAX17823 datasheet page3: Note 4: Multi-layer board. For TA > 70ºC derate 25mW/ºC.
So the Junction to ambient thermal resistance value is 40°C/W.
MAX17823H
Production
The MAX17823H is a data acquisition system for the management of high-voltage battery modules. The system features a 12-bit SAR ADC that can measure 12...
Datasheet
MAX17823H on Analog.com
MAX17823B
Production
The MAX17823B is a data acquisition system for the management of high-voltage battery modules. The system features 12-bit SAR ADC that can measure 12
cell...
Datasheet
MAX17823B on Analog.com
So the Junction to ambient thermal resistance value is 40°C/W.