onsemi 74ACTQ541PC

Overview

74ACTQ541PC from Fairchild Semiconductor is an octal non-inverting buffer/line driver with 3-STATE outputs in a 20-pin PDIP package, designed for memory and address bus driving, clock distribution, and microprocessor output port interfacing. It delivers ±24 mA output drive, operates from 4.5 V to 5.5 V, guarantees ≤7.5 ns propagation delay (tPLH/tPHL), and features FACT Quiet Series™ technology for reduced simultaneous switching noise.

For engineers reviewing the 74ACTQ541PC datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed 3-STATE timing (tPZH ≤ 9.5 ns), dynamic input thresholds (VIHD ≥ 2.2 V, VILD ≤ 0.8 V at 5.0 V), quiet-output noise suppression (VOLP ≤ 1.5 V, VOLV ≥ −1.2 V), and TTL-compatible inputs with 4 kV ESD immunity.

Technical Context

The 74ACTQ541PC implements flow-through architecture-inputs on one side (pins 1–8, 19–20), outputs on the opposite side (pins 11–18)-enabling direct microprocessor port routing and improved PCB density. Its FACT Quiet Series™ design integrates GTO™ output control and undershoot correction with split ground buses to suppress dynamic threshold shifts during high-speed switching.

It supports true 3-STATE operation via dual active-low enables (OE1, OE2), allows independent control of two 4-bit groups, and meets AC performance specifications across −40°C to +85°C with guaranteed pin-to-pin skew ≤1.0 ns (tOSHL/tOSLH) under 50 pF load conditions.

Key Specifications

Pinout & Package

74ACTQ541PC is housed in a 20-lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001 compliant, 0.300" wide, with through-hole mounting and standard 0.1" pin pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74ACTQ541PC, the 74ACT244PC offers lower cost but requires more careful PCB layout to manage noise, while the SN74ACT541N provides identical electrical and mechanical behavior with alternate supply-chain assurance-neither is pin-compatible with 74ACTQ541PC unless explicitly verified per manufacturer documentation.

Availability

74ACTQ541PC is available at Aetrix Electronics and suitable for memory subsystems, microprocessor I/O expansion, clock distribution networks, and legacy bus interface designs requiring stable component supply and long-lifecycle support.

Supply support for 74ACTQ541PC 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and logic ICs before its acquisition by ON Semiconductor in 2016.

The 74ACTQ541PC belongs to Fairchild's ACTQ Quiet Series™ logic family, engineered specifically for high-density digital systems where simultaneous switching noise, layout efficiency, and dynamic threshold stability are critical.

FAQ

What is the operating temperature range for the 74ACTQ541PC?

The 74ACTQ541PC is rated for operation from −40°C to +85°C ambient temperature. This industrial-grade range ensures reliable performance in embedded controllers, industrial PLCs, and instrumentation systems exposed to variable thermal environments. All AC and DC specifications-including propagation delay, output drive, and 3-STATE timing-are guaranteed across this full range. The device's junction temperature limit is 140°C, supporting safe operation under typical PCB power dissipation conditions.

Does the 74ACTQ541PC support true 3-STATE operation, and how is it controlled?

Yes, the 74ACTQ541PC supports true 3-STATE operation via two active-low enable inputs: OE1 (pin 19) and OE2 (pin 20). When either enable is LOW, its associated four outputs (O1–O4 for OE1, O5–O8 for OE2) enter high-impedance state. Both enables must be HIGH to activate all eight outputs. This dual-enable structure allows independent control of two 4-bit groups-essential for segmented bus arbitration and partial port isolation in microprocessor interfaces.

How does the 74ACTQ541PC reduce simultaneous switching noise compared to standard ACT devices?

The 74ACTQ541PC reduces simultaneous switching noise using FACT Quiet Series™ technology: GTO™ output control regulates edge rates, an undershoot corrector actively clamps negative voltage excursions, and a split ground bus separates I/O and core logic return paths. These features collectively limit VOLP to ≤1.5 V and VOLV to ≥−1.2 V under worst-case switching, significantly lowering ground bounce and supply rail disturbance versus standard 74ACT244 or 74ACT541 variants.

What is the maximum capacitive load the 74ACTQ541PC can drive while maintaining specified timing?

The 74ACTQ541PC's AC Electrical Characteristics-including tPLH ≤ 7.5 ns and tPZH ≤ 9.5 ns-are specified at CL = 50 pF. While it can drive higher capacitance loads (e.g., >100 pF), propagation and enable/disable delays increase nonlinearly beyond this point. For designs exceeding 50 pF, derating curves in the datasheet (Figure 1, Figure 2) must be consulted. The 74ACTQ541PC remains functional up to ±50 mA output current, but timing compliance is only guaranteed at the 50 pF test condition.

Is the 74ACTQ541PC pin-compatible with other 74ACT-series octal buffers?

No-the 74ACTQ541PC uses a flow-through pinout (inputs on left, outputs on right), unlike the interleaved pinout of 74ACT244 or 74ACT541. Pin compatibility exists only with the SN74ACT541N (identical pinout and function), but not with 74ACT244PC or 74ACT541PC. Layout reuse requires verification of pin mapping: I0–I7 occupy pins 1–8 and 19–20; O1–O8 occupy pins 11–18; OE1/OE2 are on pins 19/20-not interchangeable with single-OE devices.