Original Part
Alternative Part
SDRAM - DDR Memory IC 128Mbit Parallel 200 MHz 700 ps 66-TSOP II
SDRAM - DDR Memory IC 128Mbit Parallel 166 MHz 700 ps 66-TSOP II
1. IS43R16800E-5TLI-TR Substitution Conclusion
Direct substitution is feasible from both electrical and mechanical perspectives, with one key difference requiring validation. The core specifications of both devices (128Mbit, 8Mx16, DDR, 2.5V, 66-TSOPII) are fully compatible, including clock frequency (200MHz) and write cycle time (15ns). Bus timing and power supply requirements are directly interchangeable. The primary variances lie in the access time (50ns for the original part vs. 700ps for the ISSI device) and the interface standard description (SSTL_2 for the original vs. "Parallel" for ISSI). In practice, the ISSI chip's significantly lower data access latency offers superior performance and typically does not cause compatibility issues. However, the differing interface description necessitates verification via the detailed datasheet to confirm whether its I/O levels fully comply with the SSTL_2 standard. If they are substantively identical, substitution is viable. Otherwise, potential signal integrity risks exist. Therefore, on-board signal testing is recommended prior to replacement.
2. IS43R16800E-6TLI Substitution Conclusion
Substitution feasibility is low, primarily constrained by the downgrade in core clock frequency, which may lead to system timing mismatches. While capacity, bit width, voltage, and package are identical, and its access time (700ps) and write cycle (12ns) are superior, the critical difference is the clock frequency reduction from 200MHz in the original part to 166MHz. This results in an approximate 17% reduction in peak data transfer bandwidth for this memory device. In a practical system, if the memory controller (e.g., in a CPU or FPGA) is configured with fixed timings or only supports 200MHz, operating at the lower frequency may prevent proper controller initialization or memory access, leading to system instability or failure to boot. Direct substitution is not recommended unless the host system explicitly supports down-clocked configuration.
Analysis ID: 339A-ABA5000
Based on part parameters and for reference only. Not to be used for procurement or production.
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