For variable delay time (flexible delay time setting) type reset ICs, the formula for calculating the rise delay time (tPLH) is described as tPLH=-CCT×RCT×ln((VDD-VCTH)/VDD). What are the factors when the calculation results differ from actual measurements?
One possible factor is a probe or circuit attached to the CT pin for measurement. If an impedance other than the capacitor is attached to the CT pin the charging time will change, affecting the delay time.