1. BA4558RFVM-TR Substitution Conclusion The BA4558RFVM-TR can serve as a potential substitute for the original RC4558DGKRG4 in terms of basic functionality, but key differences require careful evaluation: output type may be incompatible (the original features differential output, whereas the BA4558 is typically single-ended), which could prevent proper operation in applications requiring differential signal processing; lower slew rate (1V/µs vs. 1.7V/µs) and lower gain-bandwidth product (2 MHz vs. 3 MHz) indicate reduced signal processing speed and frequency response, potentially affecting performance in high-frequency or fast-transient applications; lower input bias current (60 nA vs. 150 nA) helps reduce input error and improves accuracy; the minimum supply voltage is 8V (vs. 10V for the original), offering less supply flexibility, while the slightly smaller package width (2.80mm vs. 3.00mm) may require PCB layout adjustments. Overall, substitution is feasible if the application does not rely on differential output and can tolerate moderate performance degradation; otherwise, it is not recommended.