Texas Instruments SN74BCT541ADW

Overview

SN74BCT541ADW from Texas Instruments is an octal buffer/driver with 3-state outputs, designed for bus line driving and memory address register buffering in 5 V TTL-compatible systems. It operates from 4.5 V to 5.5 V, features P-N-P inputs to reduce DC loading, and uses a data flow-through pinout (inputs on one side, outputs on the other) to simplify PCB layout.

For engineers reviewing the SN74BCT541ADW datasheet, SN74BCT541ADW pinout, SN74BCT541ADW application, or SN74BCT541ADW equivalent, key selection considerations include its 20-pin SOIC (DW) package, dual active-low 3-state enable inputs (OE1/OE2), BiCMOS process for low ICCZ, and guaranteed 64 mA low-level output drive at 4.5 V.

Technical Context

The SN74BCT541ADW implements two independent 4-bit channels controlled by separate active-low 3-state enables (OE1 and OE2), each enabling eight outputs simultaneously. Its BiCMOS design integrates bipolar input stages for TTL compatibility and CMOS output stages for high current drive and low quiescent supply current (ICCZ ≤ 7 mA).

Each output exhibits asymmetric drive strength: 64 mA sink capability at VOL ≤ 0.55 V (VCC = 4.5 V, IOL = 64 mA), while sourcing only 15 mA at VOH ≥ 2.0 V (IOH = –15 mA). The 3-state control logic is a 2-input AND gate with active-low enables - either OE1 or OE2 high forces all Y outputs into high-impedance state.

Key Specifications

Pinout & Package

SN74BCT541ADW is housed in a 20-pin SOIC (DW) package measuring 7.5 mm × 12.8 mm × 2.65 mm (max height), with 1.27 mm pitch 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 octal buffer applications.

Compared with SN74ACT541DWR and SN74LS244N, the SN74BCT541ADW uniquely balances TTL compatibility, high sink current, and low ICCZ - making it optimal for upgrading legacy bus systems without sacrificing drive or thermal performance.

Availability

SN74BCT541ADW is available at Aetrix Electronics and suitable for memory address buffering, parallel bus isolation, legacy TTL system upgrades, and test equipment signal conditioning requiring stable component supply and long-term industrial availability.

Supply support for SN74BCT541ADW 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 global semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs for industrial, automotive, and communications markets.

The SN74BCT541ADW belongs to TI's BCT logic family, engineered specifically for high-current 5 V bus interfacing with reduced power consumption versus standard TTL - targeting industrial control, instrumentation, and legacy system modernization.

FAQ

What is the maximum output sink current specification for SN74BCT541ADW?

The SN74BCT541ADW guarantees a minimum output sink current (IOL) of 64 mA at VCC = 4.5 V and VOL ≤ 0.55 V, as specified in the electrical characteristics table. This rating applies per output pin under steady-state conditions and enables direct driving of terminated transmission lines or multiple TTL inputs without external amplification. The SN74BCT541ADW maintains this performance across its full operating temperature range (0°C to 70°C).

Does SN74BCT541ADW have built-in bus-hold circuitry?

No, the SN74BCT541ADW does not include bus-hold circuitry. Per TI application report SCBA004, all unused inputs must be externally held at VCC or GND using pull-up or pull-down resistors to prevent floating nodes, oscillation, or excessive ICC. This requirement applies to both A1–A8 and OE1/OE2 pins when not actively driven, and is explicitly documented in the recommended operating conditions section of the SN74BCT541ADW datasheet.

Can SN74BCT541ADW operate reliably at 4.5 V supply voltage?

Yes, the SN74BCT541ADW is fully specified to operate at 4.5 V, the minimum rated supply voltage. All key parameters - including VOH ≥ 2.0 V (at IOH = –15 mA), VOL ≤ 0.55 V (at IOL = 64 mA), and propagation delays (tPLH/tPHL ≤ 8.2 ns) - are guaranteed over the full 4.5 V to 5.5 V range. The device's BiCMOS architecture ensures stable switching thresholds and drive strength even at the lower end of its supply range, making SN74BCT541ADW suitable for margin-sensitive 5 V systems.

What is the thermal resistance (θJA) of the SN74BCT541ADW in its SOIC (DW) package?

According to the absolute maximum ratings table, the junction-to-ambient thermal resistance (θJA) for the SN74BCT541ADW in the SOIC (DW) package is 58°C/W. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad, 2 oz Cu). For continuous operation at maximum rated output current (64 mA per pin), thermal design must ensure junction temperature remains below 125°C - requiring ambient temperature limits or forced airflow when driving multiple outputs simultaneously.

How are the 3-state enable inputs (OE1 and OE2) logically configured in SN74BCT541ADW?

The SN74BCT541ADW implements a 2-input AND gate with active-low logic for 3-state control: if either OE1 or OE2 is high, all eight outputs (Y1–Y8) enter high-impedance state. Both enables must be low to activate outputs. This architecture allows independent control of Y1–Y4 (via OE1) and Y5–Y8 (via OE2), enabling partial bus gating. To ensure high-Z during power-up, TI recommends tying OE1 and OE2 to VCC through pull-up resistors (value determined by driver sink capability).