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Infineon Technologies CY7C4251-10JXCT — Memory (DRAM / SRAM / Flash / EEPROM)

CY7C4251-10JXCT Synchronous FIFO, 8 ns Access, 72K, 32-PLCC

MPNCY7C4251-10JXCT
Obsolete

Cypress CY7C4251-10JXCT, Series CY7C, Synchronous FIFO, 100 MHz data rate, 8 ns access time, 72K (8K x 9), 4.5 V~5.5 V supply, 0°C~70°C, 32-PLCC (J-Lead).

Infineon Technologies CY7C4251-10JXCT datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

CY7C4251-10JXCT specifications
ParameterValue
SeriesCY7C
MountingSurface Mount
Expansion typeDepth, Width
Voltage4.5 V ~ 5.5 V
Current - supply35mA
Operating temperature0°C~70°C
PackageTape & Reel (TR)
FunctionSynchronous
Data rate100MHz
Access time8ns
Memory size72K (8K x 9)
FWFT supportNo
Case32-LCC (J-Lead)
Bus directionalUni-Directional
Retransmit capabilityNo
Programmable flags supportYes

Product details

The Cypress CY7C4251-10JXCT is a synchronous FIFO memory in the CY7C series, organized 8K x 9 bits (72K total) and clocked at 100 MHz with an 8 ns access time. This part was designed for moderate-depth buffering in data-acquisition, telecom, and processor-to-peripheral links where a 9-bit width (data plus parity or control) and synchronous clocking keep the bus simple.

8 ns access time — timing margin at 100 MHz

At 100 MHz the clock period is 10 ns. An 8 ns access time leaves 2 ns for setup and hold on the receiving side — tight but workable if the board layout keeps trace lengths matched and the clock jitter under 200 ps. The synchronous interface eliminates the dead cycles you get with asynchronous FIFOs; the read and write pointers advance on the clock edge, so back-to-back transfers are possible. If your system runs slower than 100 MHz, the margin improves proportionally.

72K (8K x 9) — what the depth buys you

8K words of 9 bits each is a moderate buffer depth — enough to absorb bursts in a UART-to-processor link, a parallel ADC data stream, or a small packet buffer. The 9th bit is often used for parity or a control flag. Depth and width expansion are supported, so two or more of these can be cascaded for larger buffers without external logic.

Obsolete — the sourcing reality

This part is listed as obsolete. That means the only channel is surplus or broker stock. If you are repairing a board that uses this FIFO, the scorch mark is probably not on the FIFO itself — check the supply rail first, because the 35 mA max draw rarely kills the chip. For new designs, look at current-generation synchronous FIFOs from Cypress (now Infineon) or compatible parts from IDT/Renesas in the same 32-PLCC footprint, but verify pin compatibility against the datasheet before ordering.

The 32-PLCC (J-Lead) package (supplier device package 32-PLCC 11.43x13.97 mm) is a surface-mount form factor that was common through the 1990s and 2000s. Replacing it on a board requires hot-air rework with a J-lead nozzle; the pads are under the body, so inspection after soldering needs an X-ray or a borescope.

Frequently asked questions

Is CY7C4251-10JXCT obsolete?

Yes, the CY7C4251-10JXCT is listed as obsolete. It is no longer in production. For existing designs, source from surplus or broker channels; for new designs, evaluate a current-generation synchronous FIFO in a similar 32-PLCC footprint.

What is the access time of CY7C4251-10JXCT?

The access time is 8 ns, which at a 100 MHz clock rate leaves 2 ns of timing margin for setup and hold on the receiving bus.

What is the difference between synchronous and asynchronous FIFO?

A synchronous FIFO like the CY7C4251 uses a clock to latch read and write operations on every edge, enabling back-to-back transfers without dead cycles. An asynchronous FIFO uses separate read and write strobes and requires handshaking, which adds latency but can bridge different clock domains without a PLL.