1. LT1355CS8TRPBF Substitution Conclusion Direct substitution carries high risk and is not recommended. While the package is compatible and the gain-bandwidth product is similar, the core amplifier architecture shifts from J-FET to voltage feedback. This results in an input bias current (80nA vs. 20pA) that is 4000 times higher, introducing significant input current error in applications such as high-impedance sensors, integrators, or precision I-V converters. This completely negates the ultra-low input current advantage inherent to the original part's J-FET input stage. Furthermore, its output drive capability (30mA) is slightly weaker, and its minimum operating voltage (5V) is marginally higher than the original part's 4.5V, imposing further constraints for low-voltage systems. Substitution should only be considered after rigorous validation, and only in circuits where input bias current is extremely non-critical, and where its higher slew rate (400V/µs) and lower quiescent current are deemed advantageous.