1. LT1354CS8TRPBF Substitution Conclusion Direct substitution is not recommended. It may be considered only for specific applications with extremely light loads, low frequencies, and no reliance on high drive capability, and even then requires careful evaluation. The rationale is as follows: While the LT1354 offers significant advantages in input precision (300µV vs. 2.5mV offset voltage, 80nA vs. 2.5µA bias current) and quiescent current (1mA vs. 8.5mA) compared to the THS4051IDR, there are two critical parameter mismatches. First, its gain-bandwidth product is only 12MHz, far below the THS4051's -3dB bandwidth of 70MHz. Under high closed-loop gain or when processing high-frequency signals, the usable bandwidth of the LT1354 will be severely insufficient, leading to significantly degraded high-frequency system response. Second, its output drive current is only 30mA, substantially lower than the THS4051's 100mA. The LT1354 has very weak capability to drive low-impedance loads (e.g., cables, ADCs, low-impedance headphones) or capacitive loads, which may result in reduced output swing, increased distortion, or even instability. Functional equivalence cannot be achieved unless the application has exceptionally low requirements for both bandwidth and output current.