1. Speed Grade and Core Performance - The 71V65603S100BQI supports a 100 MHz clock frequency (corresponding to a 10 ns cycle), with a specified access time of 5 ns. - The “85” in the 71V65703S85BQI typically denotes an 85 MHz maximum clock (corresponding to a ~11.8 ns cycle), with a specified access time of 8.5 ns. - The 71V65703S85BQI has a lower‑performance core or pipeline design, resulting in a lower sustainable operating frequency. At the same clock frequency, the former provides greater timing margin and is better suited for higher‑bandwidth or lower‑latency applications. 2. Interpretation of Timing Parameters - The two devices differ in their specified “Access Time” (5 ns vs. 8.5 ns). In synchronous SRAMs, this parameter typically represents the maximum clock‑to‑data‑output delay (tCO). - The 71V65703S85BQI exhibits slower data‑output response, which reduces the valid data window in high‑speed systems. This places tighter setup‑and‑hold‑time requirements on the system controller (e.g., FPGA or processor) and may limit the maximum achievable system frequency. 3. Speed Grading Implied by Part Numbering - The “100” and “85” in Renesas’ part numbering directly indicate the maximum rated clock frequency (100 MHz vs. 85 MHz). - These are tested and verified speed grades that directly impact system clock planning. If the original system operates above 85 MHz, replacement will fail to meet timing specifications and may cause read/write errors. Recommended Actions: If substitution is being considered, perform the following verifications: 1. Confirm that the actual system operating frequency is ≤85 MHz and conduct timing analysis under worst‑case conditions. 2. Compare the DC characteristics, pin capacitance, and switching characteristics in both datasheets to ensure electrical compatibility. 3. Evaluate whether any reduction in system bandwidth due to the lower operating frequency is acceptable.