1. HFZ 1608PF-600T40 Substitution Conclusion The HFZ 1608PF-600T40 is a viable substitute for the original part ACML-0603U-700-T, with several key distinctions to note. Its impedance is 60 Ω at 100 MHz, lower than the original’s 70 Ω, resulting in slightly weaker high‑frequency noise suppression at the same frequency. Additionally, a minor length difference (1.60 mm vs. 1.65 mm) does not affect solder compatibility with the 0603 footprint. Given that both share identical rated current (4A), DC resistance (20 mΩ), package style, and height, this substitution is acceptable for general power‑line filtering applications. However, if the circuit has stringent impedance requirements at specific frequencies, the filtering performance should be reviewed to ensure it still meets the design margin.