What this FIFO does on your board
The CD40105BE is a 64-bit asynchronous FIFO organized as 16 words by 4 bits — a shallow, narrow buffer for clock-domain crossing or rate-matching between a slow sensor bus and a faster processor port. The 16-DIP (0.300", 7.62mm) through-hole package means it plugs into a standard 300-mil socket or solders into a plated through-hole board — no fine-pitch reflow, no BGA x-ray inspection. A technician can replace it in the field with a desoldering iron.
Asynchronous operation and expandability
Asynchronous FIFO means the read and write clocks are independent — no common clock tree needed. The CD40105BE handles data transfers between two unrelated clock domains, for example a 1 kHz temperature sensor reading into a 10 MHz acquisition controller, without metastability if the setup/hold timing is respected. Depth and width expansion are supported: cascade multiple devices to increase the word count or the bit width. A 16×4 block can become 32×4 by tying the full-flag outputs, or 16×8 by wiring two devices in parallel with common read/write controls — no external glue logic required beyond the flag gating. No FWFT (First-Word Fall-Through) support and no programmable flags — the flag architecture is fixed: the full flag goes high when the FIFO is full, the empty flag goes high when it is empty, and the half-full flag indicates the midpoint. For designs that need early-warning flags or a look-ahead data output, a different FIFO family (e.g., the 74ACT series) would be a better fit.
RoHS3 compliant (ROHS3 Compliant per the TI lifecycle record). No REACH or UL documentation is on the record, but the RoHS declaration covers the EU material restriction requirements for most industrial and commercial applications.