{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"CY7C421-20JXCT","brand":"Infineon Technologies","brandSlug":"infineon","productSlug":"CY7C421-20JXCT","canonicalUrl":"https://icboms.com/infineon/CY7C421-20JXCT","factsUrl":"https://icboms.com/api/mcp/products/CY7C421-20JXCT","rawCanonicalId":null},"summary":{"shortDescription":"Cypress CY7C421-20JXCT asynchronous FIFO, 4.5 Kbit (512 x 9), 20 ns access time, 50 MHz data rate, 4.5 V~5.5 V supply, 32-PLCC (J-lead), 0°C~70°C, Tape & Reel.","salesMarkdown":"The Cypress CY7C421-20JXCT is a 4.5 Kbit (512 x 9) asynchronous FIFO memory with a 20 ns access time and 50 MHz data rate, designed for rate-matching, buffering, and data aggregation in 5 V logic systems. It supports depth and width expansion for scaling buffer capacity, includes retransmit capability for error recovery, and comes in a 32-PLCC (J-lead) surface-mount package for board-level assembly. The 20 ns access time and 50 MHz data rate set the read/write cycle window. In a 5 V system with typical 8–10 ns propagation delays from the controller and bus transceivers, the 20 ns access leaves roughly 5–7 ns of setup-and-hold margin at 50 MHz — adequate for synchronous handshaking but tight for backplane expansion. If the design runs multiple FIFOs in cascade, budget the cumulative delay through the depth-expansion logic. ## 512 x 9 organization — what the extra bit buys you The 9-bit width (512 x 9) stores an eighth data bit plus a parity or control bit per word, common in 8-bit buses with parity or 9-bit serial protocols. The 4.5 Kbit depth buffers about 512 bytes of burst data — enough for a single Ethernet frame fragment or a few hundred sensor readings, but not for long packet streams. Depth and width expansion are supported, so multiple devices can cascade without external muxing. ## Lifecycle reality: obsolete, but sourced to order The CY7C421-20JXCT is officially obsolete per the manufacturer. For new designs, evaluate the Cypress CY7C42x family (e.g., CY7C421-20JXC in tube or CY7C421-20JXCT in tape-and-reel) as a form-fit-function cross if the stock holds — note that the -20JXC and -20JXCT share the same 32-PLCC (11.43x13.97) footprint and electrical ratings, differing only in packaging medium.","metaTitle":"CY7C421-20JXCT FIFO, 4.5K (512 x 9), 20 ns","metaDescription":"CY7C421-20JXCT asynchronous FIFO, 50 MHz, 20 ns access, 4.5 Kbit (512 x 9), 32-PLCC. Obsolete.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Obsolete","categoryPath":["Memory (DRAM / SRAM / Flash / EEPROM)"],"specifications":{"Mfr":"Infineon Technologies","Series":"CY7C","Package":"Tape & Reel (TR)","Function":"Asynchronous","Data Rate":"50MHz","Access Time":"20ns","Memory Size":"4.5K (512 x 9)","FWFT Support":"No","Mounting Type":"Surface Mount","Expansion Type":"Depth, Width","Package / Case":"32-LCC (J-Lead)","Product Status":"Obsolete","Bus Directional":"Uni-Directional","lifecycle_stage":"eol_hot","Voltage - Supply":"4.5 V ~ 5.5 V","Base Product Number":"7C421","Operating Temperature":"0°C~70°C","Retransmit Capability":"Yes","Current - Supply (Max)":"55mA","Supplier Device Package":"32-PLCC (11.43x13.97)","Programmable Flags Support":"No"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/4ff2b25f88134e2a3806033ba16d7ff7.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the replacement for CY7C421-20JXCT?","answer":"No direct pin-compatible replacement is listed in the manufacturer's records. The CY7C421-20JXC (tube packaging) is electrically and footprint-identical, differing only in the shipping medium. For new designs, evaluate the broader Cypress CY7C42x FIFO family for a functional match."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/infineon/CY7C421-20JXCT","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/infineon/CY7C421-20JXCT when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-17T19:50:00.618Z","lastPublished":"2026-07-17T19:50:00.618Z","indexable":true}}