The resistor was chosen such that STBY is between 0.1-0.6V for VL<=2.25V, if VL is larger than 2.25V, the range can be 0.1-0.8V to stay in the slow slew mode, different R value can be used.
The resister we recommended is 26.1K, based on the accuracy and price range. They can have some freedom to choose the external R value to be bigger, as far as it obeys the rule mentioned above.
If STBY voltage is < 0.1V or connected to GND, then normal operation. If STBY is >0.8V but less than the VIH with VL >=2.25V, the part will enter undetermined mode. Only if STBY is larger than VIH, then it will enter standby mode.”