1. PL123-05SC-R Substitution Conclusion Based on a comparison of key parameters, the PL123-05SC-R is essentially identical to the original part NB2305AI1DR2G in terms of package, supply voltage (3–3.6 V), input-to-output ratio (1:5), maximum frequency (134 MHz vs. 133 MHz), and I/O type (CMOS/Clock), while also offering high pin compatibility. As a result, it can serve as a direct replacement in most general clock distribution applications. The primary difference lies in the PL123-05SC-R’s explicit specification of PLL bypass support (“Yes with Bypass”), a feature not documented for the original device. When the PLL is bypassed, the output clock directly follows the input clock, which may eliminate the zero‑delay characteristic but provides greater flexibility in the clock path. If the application relies on strict zero‑delay synchronization—such as in high‑performance processor or FPGA clock trees—the timing in bypass mode must be verified to ensure it meets requirements. If the design only requires clock buffering and distribution with minor frequency tolerance, the substitution is acceptable.