100 MHz synchronous FIFO — the speed tier that defines the datapath
The CY7C4245-10ASXC from Cypress is a synchronous FIFO memory organized as 4K words by 18 bits, giving 72 Kbit of storage. Its 100 MHz data rate and 8 ns access time are the specs that determine whether this part can buffer a high-speed DSP or FPGA datapath without inserting wait states. At 100 MHz, the read/write cycle time is 10 ns, and the 8 ns access means the data appears on the bus with 2 ns of margin before the next clock edge — tight but workable for a 5 V logic system. The 18-bit width (16 data + 2 parity or control bits) is a common choice for bridging 16-bit buses with error detection or for packing two 8-bit channels.
5 V supply, 45 mA max — the legacy power rail
That 5 V rail is increasingly rare in new designs that have moved to 3.3 V or lower, but it is still common in legacy telecom, test equipment, and industrial control boards. If your BOM already carries a 5 V supply, this part drops in without a regulator. The 45 mA maximum supply current is modest for a 5 V part — about 225 mW dissipation — so no special thermal management is needed in the 64-TQFP package.
If your application sees temperature extremes — a factory floor, an outdoor cabinet, or under-hood — this is not the right FIFO. The commercial grade is typical for the CY7C family, but it is a hard constraint for any BOM destined for extended-temperature gear.
The CY7C4245-10ASXC is listed as obsolete. Cypress (now part of Infineon) no longer manufactures this specific speed grade. That means no factory orders, no last-time-buy windows — the only channel is the surplus and broker market. For a sustainment program or a repair depot that needs this exact part, the sourcing strategy is to buy available inventory now and qualify a replacement in parallel. The official Cypress product status does not list a direct successor for the -10ASXC variant, so a form-fit-function replacement will require a cross-reference search against the broader CY7C42xx family or a newer synchronous FIFO from a different vendor.
64-LQFP footprint — the board-lock detail
The part comes in a 64-LQFP package (also specified as 64-TQFP, 10x10 mm body). This is a standard fine-pitch QFP with 0.5 mm lead pitch. The footprint is not unique to Cypress — many 64-pin TQFP memories and FIFOs share the same land pattern — but the exact pinout is specific to the CY7C4245 function. If you are replacing an existing FIFO on a board, verify that the pin mapping matches your layout; the CY7C4245 uses a unidirectional bus architecture with separate read and write clocks.
Retransmit and programmable flags — the control-plane features
This FIFO supports retransmit capability, which lets the read pointer reset to a previously marked location without clearing the entire memory — useful for packet retry in communication systems. It also supports programmable flags, so the almost-full and almost-empty thresholds can be set in software rather than being fixed at hardware reset. These features are standard on Cypress synchronous FIFOs and are what distinguish this part from simpler asynchronous FIFOs that lack flag programmability.