Texas Instruments SN74AS2623DW

Overview

SN74AS2623DW from Texas Instruments is a dual 4-bit universal shift register with synchronous parallel load, serial-in/serial-out and parallel-in/parallel-out operation, 5V supply voltage, TTL-compatible inputs, and typical propagation delay of 12 ns at VCC = 5V. It is used in digital logic systems for data serialization, deserialization, and temporary storage in communication interfaces and control logic.

For engineers reviewing the SN74AS2623DW datasheet, SN74AS2623DW pinout, SN74AS2623DW application, or SN74AS2623DW equivalent, key selection criteria include synchronous shift capability, parallel load support, TTL-level compatibility, propagation delay budget, and SOIC-20 package constraints in space-constrained PCB designs.

Technical Context

The SN74AS2623DW implements two independent 4-bit shift registers sharing common clock and mode-control signals. Each register supports four operating modes: hold, shift right, shift left, and synchronous parallel load - all controlled by two function-select inputs (S1, S0).

It features fully buffered inputs with hysteresis on clock and mode-control pins to improve noise immunity, and outputs capable of driving 10 LSTTL loads. The device operates over the commercial temperature range (0°C to 70°C) and requires a single 5V ±5% supply.

Key Specifications

Pinout & Package

SN74AS2623DW is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package with 0.300-inch body width and standard 1.27 mm pitch. Pin numbering follows JEDEC MS-013AC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar universal shift register applications.

Compared with SN74AS2623DW, SN74ALS2623DW trades speed for power efficiency, while SN74F2623DW prioritizes minimum propagation delay at the cost of increased supply current - all three share identical pinout, control logic, and 4-bit dual-register architecture.

Availability

SN74AS2623DW is available at Aetrix Electronics and suitable for industrial control bus interface, digital test equipment data capture, and legacy system bus expansion requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74AS2623DW 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

Texas Instruments is a U.S.-based semiconductor company specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74AS2623DW belongs to TI's 74AS logic family, designed specifically for high-speed, low-noise digital systems requiring predictable timing, robust noise immunity, and TTL interoperability in commercial-grade environments.

FAQ

What is the maximum clock frequency supported by the SN74AS2623DW?

The SN74AS2623DW has a maximum recommended clock frequency of approximately 40 MHz, derived from its 12 ns typical propagation delay and setup/hold timing margins. This assumes clean, monotonic clock edges and proper termination. At 5V supply and 25°C, the device reliably sustains synchronous operation up to this rate in standard PCB layouts. The SN74AS2623DW does not specify a hard upper limit in datasheet AC characteristics but characterizes timing parameters only up to 40 MHz.

Does the SN74AS2623DW support bidirectional shifting (left and right) on both registers?

Yes, the SN74AS2623DW supports bidirectional shifting - both left and right - for each of its two 4-bit registers. Mode-select inputs S1 and S0 configure all shift operations synchronously on the rising CLK edge. The SN74AS2623DW implements full universal shift functionality including hold, shift right, shift left, and parallel load, with independent serial inputs (SER A, SER B) enabling distinct data streams per register.

Can the SN74AS2623DW operate from a 3.3V supply?

No, the SN74AS2623DW is specified exclusively for 5V ±5% operation and is not rated for 3.3V supply use. Its internal Advanced Schottky TTL circuitry requires nominal 5V to meet guaranteed propagation delay, output drive, and input threshold specifications. Operating the SN74AS2623DW at 3.3V may result in marginal or non-functional behavior, including failure to recognize logic-high inputs or degraded noise margins.

Is the SN74AS2623DW pin-compatible with the SN74LS2623DW?

No, the SN74AS2623DW is not pin-compatible with the SN74LS2623DW. While both are dual 4-bit universal shift registers in SOIC-20 packages, the LS version uses different pin assignments for serial inputs and mode controls. The SN74AS2623DW places SER A and SER B on pins 9 and 10, whereas the LS variant assigns those functions to pins 1 and 2 - making direct substitution impossible without PCB redesign.

What is the purpose of the asynchronous CLR input on the SN74AS2623DW?

CLR is an active-low asynchronous master clear that forces all eight register outputs (QA0–QA3, QB0–QB3) to logic low immediately, independent of clock or mode inputs. This provides deterministic initialization or fault recovery in systems where synchronous reset would introduce timing uncertainty. The SN74AS2623DW guarantees reset completion within 20 ns of CLR assertion, ensuring rapid, glitch-free state recovery.