2. MC4558CDT Substitution Conclusion Largely not feasible and suitable only for non-critical applications with minimal requirements. The MC4558CDT is a general-purpose bipolar-input dual op-amp. Its input stage technology fundamentally differs from the original JFET type, resulting in substantial gaps in key parameters: its input bias current is as high as 50 nA (12,500 times that of the LT1169), and its input offset voltage is also higher at 1 mV. It is entirely unsuitable for circuits requiring high input impedance, low input current, or high DC precision, such as sensor interfaces, integrators, or sample-and-hold circuits. Its slew rate (2.2V/µs) is low, limiting large-signal bandwidth. Although its supply voltage range is compatible and its power consumption is lower, the severe degradation in core input characteristics would fundamentally alter circuit performance if directly substituted. It should only be considered if the original circuit is extremely insensitive to input error and impedance, such as in certain audio filtering or low-precision comparator applications.