1. PL123-05SC Substitution Conclusion From a core parameter perspective, the PL123-05SC is fully compatible with the original part in terms of supply voltage (3-3.6V), number of outputs (1:5), package (8-SOIC), and maximum frequency (134MHz), meeting the physical and basic electrical conditions for a direct drop-in replacement. The critical distinction lies in their functional definitions. The original part is a dedicated "zero-delay buffer," whose core performance metrics are phase alignment between output and input clocks (near-zero delay) and low jitter. In contrast, the PL123-05SC is described as a "clock multiplexer." Its PLL features a bypass mode, and its function is more focused on clock selection and distribution. Its datasheet may not guarantee "zero-delay" as a core characteristic. In applications with stringent requirements for clock synchronization accuracy and jitter (e.g., high-speed data acquisition, precision timing systems), a direct substitution could lead to degraded or unstable system timing performance. For general digital circuits requiring only clock fanout and basic synchronization, the substitution is highly feasible. The conclusion is a conditional substitution. A final determination can only be made after evaluating the specific application's timing requirements and comparing key timing parameters such as jitter and output skew between the two devices.