Nexperia USA Inc. 74HC40105D,653

Overview

74HC40105D,653 from Nexperia is a 4-bit × 16-word asynchronous first-in/first-out (FIFO) buffer IC designed for elastic data buffering between clock domains. It features independent SI/SO controls, DIR/DOR status flags, 3-state outputs, and operates across -40 °C to +125 °C. Used in UART bridging, video frame buffering, and protocol translation where input/output data rates differ.

For engineers reviewing the 74HC40105D,653 datasheet, 74HC40105D,653 pinout, 74HC40105D,653 application, or 74HC40105D,653 equivalent, key selection criteria include ripple-through delay (≤400 ns @ VCC=4.5 V), burst-mode frequency (up to 30 MHz), DIR/DOR flag timing accuracy, and SO16 package compatibility with high-density PCB layouts.

Technical Context

The 74HC40105 implements a fully asynchronous FIFO using cascaded control flip-flops that generate self-timed clock pulses to shift data through 16 stages. Each stage contains four D-latches and one marker bit, enabling automatic "bubble-up" of empty locations and "ripple-through" of valid data without external clocks.

Its dual-edge-triggered SI (LOW→HIGH) and SO (HIGH→LOW) inputs decouple data movement from system clocks, while DIR and DOR flags provide real-time full/empty status. The MR input asynchronously clears all control logic and invalidates stored data, setting DIR=HIGH and DOR=LOW.

Key Specifications

Pinout & Package

74HC40105D,653 is housed in a plastic small outline package (SO16), SOT109-1, with 16 leads and 3.9 mm body width. Pin 1 is marked by a bevelled corner or dot; pin numbering follows standard SOIC convention (counterclockwise from pin 1).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FIFO buffer applications.

Compared with 74HC40105D,653, the TSSOP variant offers identical functionality in a smaller footprint, while the SN74ACT2227N trades integrated status signaling for greater throughput and wider data width - making it preferable for high-speed 8-bit buses but requiring additional control logic.

Availability

74HC40105D,653 is available at Aetrix Electronics and suitable for UART bridging, video frame buffering, industrial sensor aggregation, and legacy bus interfacing requiring stable component supply across extended temperature ranges.

Supply support for 74HC40105D,653 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Nexperia is a global semiconductor expert focused on high-volume, high-reliability logic, discrete, and MOSFET solutions for automotive, industrial, and consumer markets.

The 74HC40105 belongs to Nexperia's HC logic family, engineered for robust asynchronous data buffering in mixed-signal systems where clock domain isolation and deterministic latency are essential.

FAQ

What is the minimum pulse width required for reliable SI and SO operation?

The minimum SI and SO pulse widths are 7 ns and 14 ns respectively at VCC = 4.5 V, per Table 10. These values ensure proper edge detection by internal Schmitt-trigger inputs and reliable triggering of the ripple-through or bubble-up sequence. Pulses shorter than these may fail to register, especially under temperature extremes or voltage droop.

Can unused data input pins (e.g., D2, D3) be left floating?

No - unused data input pins must be tied to either VCC or GND to prevent floating inputs from causing excessive current draw or unpredictable logic states. The datasheet explicitly states that for reduced word-length configurations (e.g., 2×16), unused Dn pins should be hard-wired, not left open.

How does the MR signal interact with ongoing SI/SO operations?

An active HIGH MR pulse asynchronously clears all control flip-flops, invalidates stored data, and forces DIR=HIGH and DOR=LOW regardless of current FIFO state. Any in-progress ripple-through or bubble-up is immediately halted, and the device enters a known reset state - making MR ideal for power-on initialization or error recovery.

Is the 74HC40105D,653 compatible with 3.3 V-only systems?

Yes - the device is fully specified down to VCC = 2.0 V and supports 3.3 V operation with guaranteed VIH = 2.1 V and VIL = 1.35 V at that supply. All DC and AC parameters, including propagation delays and output drive, are validated across the 2.0–6.0 V range, ensuring interoperability with 3.3 V logic families.