Texas Instruments SN74LS541NSRG4

Overview

SN74LS541NSRG4 from Texas Instruments is an octal buffer/line driver with 3-state outputs, designed for bidirectional data bus interfacing in TTL-based digital systems. It features 8 non-inverting channels, ±24 mA output drive capability, 15 ns typical propagation delay (t_PLH/t_PHL), and operates over 0°C to 70°C. It is used in microprocessor address/data bus buffering, memory I/O expansion, and industrial control backplane interfaces.

For engineers reviewing the SN74LS541NSRG4 datasheet, SN74LS541NSRG4 pinout, SN74LS541NSRG4 application, or SN74LS541NSRG4 equivalent, key selection criteria include 3-state output control timing, DC drive strength at V_CC = 5 V, input compatibility with LS/TTL logic families, and SOP-20 package thermal and layout constraints for high-density PCBs.

Technical Context

The SN74LS541NSRG4 implements dual active-low output-enable controls (OE1̅, OE2̅) enabling independent gating of two groups of four drivers. Its bipolar TTL circuitry delivers guaranteed 24 mA sink and 15 mA source output current under standard load conditions, supporting direct connection to multiple LS loads without external pull-ups.

Input thresholds align with standard TTL specifications (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), ensuring interoperability with SN74LSxx, SN74Sxx, and legacy 74xx logic families. Propagation delays are characterized at V_CC = 5 V ± 0.5 V, T_A = 25°C, with t_PLH = t_PHL = 15 ns max into R_L = 400 Ω, C_L = 15 pF.

Key Specifications

Pinout & Package

SOP-20 (Small Outline Package, 0.300" wide, 1.27 mm pitch) with gull-wing leads; 2.65 mm max height; RoHS-compliant NiPdAu lead finish; MSL Level-1 (unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS244N and SN74HC244PW, the SN74LS541NSRG4 uniquely balances legacy TTL interoperability, 24 mA drive headroom, and SOP-20 surface-mount compatibility-making it optimal for repairing or upgrading commercial-grade 5 V digital systems without layout changes.

Availability

SN74LS541NSRG4 is available at Aetrix Electronics and suitable for microprocessor bus interface, industrial I/O expansion, legacy system repair, and test equipment signal conditioning requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74LS541NSRG4 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 leader founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial and automotive qualification.

The SN74LS541NSRG4 belongs to TI's legacy 74LS logic family, engineered for reliability and interoperability in commercial-grade digital systems requiring proven TTL performance and long-lifecycle support.

FAQ

What is the maximum output current specification for SN74LS541NSRG4?

The SN74LS541NSRG4 guarantees a minimum output sink current of 24 mA and source current of 15 mA at V_CC = 5 V, measured under standard test conditions (R_L = 400 Ω, C_L = 15 pF). These values are specified in the official TI datasheet SDLS180 and validated across the 0°C to 70°C operating range. This drive strength allows the SN74LS541NSRG4 to directly interface with up to 20 LS-TTL inputs without external buffering.

Is SN74LS541NSRG4 pin-compatible with SN74LS244?

Yes, SN74LS541NSRG4 shares identical pin assignments with SN74LS244 in the SOP-20 package-inputs A1–A8 on pins 1–8, outputs Y1–Y8 on pins 9–16, OE1̅/OE2̅ on pins 17/19, GND on pin 18, and V_CC on pin 20. However, SN74LS541NSRG4 offers higher output drive (24 mA vs. 20 mA) and identical propagation delay, making it a functional upgrade in most 74LS244 applications.

Does SN74LS541NSRG4 support 3.3 V logic inputs?

No, SN74LS541NSRG4 is a strict 5 V TTL device with input thresholds defined for V_IL ≤ 0.8 V and V_IH ≥ 2.0 V at V_CC = 5 V. It does not guarantee correct operation with 3.3 V CMOS logic levels (V_IH ≈ 2.0 V min but marginal), and applying 3.3 V inputs may result in undefined behavior or increased power consumption. For mixed-voltage systems, level translation is required before connecting to the SN74LS541NSRG4.

What is the thermal resistance (θ_JA) of SN74LS541NSRG4 in SOP-20 package?

The junction-to-ambient thermal resistance (θ_JA) for SN74LS541NSRG4 in the SOP-20 (NS) package is 100°C/W, as documented in TI's package thermal characterization reports for the NS package variant. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad, 1 oz Cu). Actual θ_JA will vary based on PCB layout, copper area, and airflow-designers should verify junction temperature using worst-case power dissipation (≈120 mW typical) and ambient conditions.

Can SN74LS541NSRG4 be used in place of SN74LS540?

Yes, SN74LS541NSRG4 can replace SN74LS540 in most applications because both are octal 3-state buffers with identical pinouts and electrical specifications. The only difference is logical polarity: SN74LS540 has inverting outputs, while SN74LS541NSRG4 has non-inverting outputs. Therefore, substitution requires verifying that signal inversion is acceptable-or adding external inverters-if the original design depends on inverted output behavior.