Texas Instruments SN74ALS232BDWR

Overview

SN74ALS232BDWR from Texas Instruments is a 16 × 4 asynchronous first-in, first-out (FIFO) memory IC with independent write/read clocks, 40 MHz maximum clock frequency, 14 ns typical fall-through time, 3-state outputs, and operation across 0°C to 70°C. It serves as a data buffering interface between mismatched-speed digital subsystems in communication controllers and protocol bridges.

For engineers reviewing the SN74ALS232BDWR datasheet, SN74ALS232BDWR pinout, SN74ALS232BDWR application, or SN74ALS232BDWR equivalent, key selection criteria include asynchronous dual-clock timing margins, EMPTY/FULL flag behavior under reset, 3-state output enable timing, and compatibility with ALS logic voltage thresholds and drive strength.

Technical Context

This FIFO implements independent write (LDCK) and read (UNCK) pointers using dual ring counters, enabling true asynchronous operation without shared clock domains. Its status flags (FULL, EMPTY) are edge-triggered and synchronized to respective clocks, with FULL low when full and EMPTY low when empty.

Reset (RST) asynchronously clears internal stack pointers and forces EMPTY = low / FULL = high, while Q outputs retain prior state. Output-enable (OE) controls 3-state drivers without affecting status flags, and cascading is supported only in word-width (parallel) direction-not depth.

Key Specifications

Pinout & Package

SN74ALS232BDWR is housed in a 20-pin plastic small-outline (SOIC) package (DW), with 300-mil width and gull-wing leads. Pin 1 is marked by a beveled corner or notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALS232BDWR, SN74AS232N delivers lower latency at higher power cost and identical layout, while 7203L15 trades speed for CMOS efficiency but mandates board-level changes and signal polarity adaptation.

Availability

SN74ALS232BDWR is available at Aetrix Electronics and suitable for UART buffering, parallel bus bridging, protocol translation interfaces, and legacy system glue logic requiring stable component supply and long-term obsolescence support.

Supply support for SN74ALS232BDWR 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74ALS232BDWR belongs to TI's legacy ALS logic family, designed specifically for high-speed, low-power asynchronous data buffering in 5 V TTL-compatible systems requiring deterministic timing and robust status signaling.

FAQ

What is the maximum clock frequency supported by the SN74ALS232BDWR?

The SN74ALS232BDWR supports a maximum clock frequency of 40 MHz for both LDCK and UNCK inputs under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C). At 50% duty cycle, the practical limit is 33.3 MHz. This specification is verified in the timing requirements table of the official TI datasheet SCAS251B.

How does the RST input affect the EMPTY and FULL flags in the SN74ALS232BDWR?

A low pulse on the RST input of the SN74ALS232BDWR asynchronously resets internal read/write pointers and forces EMPTY = low and FULL = high, regardless of current memory state. The Q outputs retain their prior logic levels and are not cleared. After RST release, the first LDCK↑ transitions EMPTY to high and presents valid data on Q0–Q3, as confirmed in the functional description of the SN74ALS232BDWR datasheet.

Is the SN74ALS232BDWR pin-compatible with other FIFO devices in the SN74ALS family?

Yes, the SN74ALS232BDWR shares identical pinout and function with SN74ALS232BN (PDIP) and SN74ALS232BFN (chip carrier), as documented in TI's SCAS251B datasheet top-view diagrams. All three variants use the same DW/N/FN package pin numbering for LDCK, UNCK, D0–D3, Q0–Q3, RST, OE, FULL, EMPTY, VCC, and GND, enabling direct socket or layout interchange within the same package footprint.

What is the fall-through time specification for the SN74ALS232BDWR, and how is it measured?

The SN74ALS232BDWR has a typical fall-through time of 14 ns, defined as the propagation delay from LDCK↑ to valid data appearing on any Q output for the first stored word. This value is measured under VCC = 5 V and TA = 25°C, with load conditions per TI's standard test setup (CL = 50 pF, R1 = 500 Ω), and appears in the switching characteristics table of the SN74ALS232BDWR datasheet SCAS251B.

Does the SN74ALS232BDWR support cascading to increase word-width or word-depth?

The SN74ALS232BDWR supports cascading only in the word-width direction (e.g., connecting multiple units to form 16 × 8 or 16 × 16 FIFOs) using shared LDCK, UNCK, RST, and OE signals with staggered D/Q lines. Cascading in word-depth (e.g., 32 × 4) is explicitly unsupported due to lack of internal chaining logic or overflow signaling, as stated in the device description section of the SN74ALS232BDWR datasheet.