Original Part
SRAM - Synchronous, SDR (ZBT) Memory IC 9Mbit Parallel 8 ns 165-CABGA (13x15)
Alternative Part
SRAM - Synchronous, SDR (ZBT) Memory IC 9Mbit Parallel 8.5 ns 165-CABGA (13x15)
SRAM - Synchronous, SDR Memory IC 9Mbit Parallel 117 MHz 7.5 ns 165-TFBGA (13x15)
1. 71V65703S85BQI Substitution Conclusion
Fully viable; this constitutes a direct, speed-grade downgrade substitution within the same product family. The 71V65703S85BQI and the original part, 71V65703S80BQI, are from the same manufacturer, Renesas, and belong to the identical product series. They are completely consistent in terms of memory density, organization, interface, voltage, package, and the core ZBT (Zero Bus Turnaround) technology. The sole difference lies in the access time, which has increased from 8.0 ns to 8.5 ns, resulting in a slightly lower maximum operating frequency for the chip and a reduction in system timing margin.
In applications where the original design's clock frequency does not approach the chip's performance limit, this variance is generally acceptable. Post-substitution, it is critical to verify that timing requirements are still met under extreme conditions, such as high and low temperature, to ensure system reliability.
2. IS64LF25636A-7.5B3LA3-TR Substitution Conclusion
Conditionally compatible; core architecture and timing compatibility require thorough verification. This ISSI part is compatible with the original model in key parameters (density, organization, voltage, package). Its 7.5 ns access time (corresponding to approximately 117 MHz operation) offers superior performance compared to the original part.
The discrepancy lies in its technical description, listed as "SRAM - Synchronous, SDR," versus the original part's explicit "SDR (ZBT)" designation. It may lack the defining characteristics of the ZBT architecture—namely, the ability to perform a read or write operation on every clock cycle without inserting wait states. If the original system logic relies on this ZBT feature for seamless pipeline operation, direct substitution could lead to data corruption or performance degradation.
Prior to replacement, it is essential to confirm whether the original application utilizes ZBT functionality. A meticulous comparison of the two chips' datasheets is mandatory, focusing on differences in read/write cycles, burst modes, and timing diagrams.
Analysis ID: 66E6-9D76000
Based on part parameters and for reference only. Not to be used for procurement or production.
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