20 ns tag SRAM for cache systems
The Texas Instruments SN74ACT2150A-20NT is a cache tag SRAM organized 512 words by 8 bits, with a 20 ns access time.
Fit for new designs and BOM continuity
That means no last-time-buy scramble or forced redesign for the foreseeable future.
What the 20 ns access time means for the bus
In a typical cache controller, this sets the minimum cycle time for tag lookups. At 20 ns, the part supports a 50 MHz bus clock with zero wait states — the tag data arrives before the next clock edge. If your system runs faster than 50 MHz, you will need to insert wait states or look at a faster SRAM. The 512x8 depth (512 tag entries, each 8 bits wide) is sized for moderate cache sizes — think 256 KB to 1 MB L2 caches with 32-byte or 64-byte lines.