onsemi 74ACQ244PC

Overview

74ACQ244PC from Fairchild Semiconductor is an octal non-inverting 3-STATE buffer/line driver in PDIP-20 package, designed for memory address driving, clock distribution, and bus interfacing with simultaneous switching noise suppression. It operates from 2.0V to 6.0V, delivers ±24 mA output drive, and guarantees ≤1.5 ns output-to-output skew at 5.0V.

For engineers reviewing the 74ACQ244PC datasheet, pinout, applications, or equivalent options, key selection criteria include quiet-switching performance (VOLP ≤1.5 V, VOLV ≥−1.2 V), dynamic input thresholds (VIHD/VILD), 3-STATE enable timing (tPZL ≤12.5 ns), and PDIP-compatible layout compatibility with legacy TTL/CMOS systems.

Technical Context

The 74ACQ244PC implements Fairchild's Quiet Series™ architecture with GTO™ output control and undershoot correction, coupled with a split ground bus to minimize simultaneous switching noise. Its dual 4-bit groups (OE1 controls O0–O3; OE2 controls O4–O7) support independent bus segment control.

It features guaranteed dynamic threshold performance under 1 MHz switching with (n−1) inputs toggling - validated per Figure 2 test setup - and meets JEDEC MS-001 PDIP mechanical standards with 0.300" body width and 0.100" lead pitch.

Key Specifications

Pinout & Package

74ACQ244PC is housed in a 20-lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001 compliant, with 0.300" wide body and 0.100" lead pitch. Pin 1 is marked by notch or dot; pin numbering follows standard DIP convention (counterclockwise from top-left).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal 3-STATE buffer applications.

Compared with 74ACQ244PC, 74AC244PC offers lower cost but sacrifices simultaneous switching noise control, while SN74ACT244N provides stricter 5V timing but omits documented quiet-output behavior and split ground design - making 74ACQ244PC uniquely suited for mixed-signal, noise-sensitive bus interfaces.

Availability

74ACQ244PC is available at Aetrix Electronics and suitable for memory address buffering, clock distribution, and legacy bus interface applications requiring stable component supply, long-term obsolescence management, and PDIP-20 through-hole compatibility.

Supply support for 74ACQ244PC 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 analog and mixed-signal ICs, acquired by ON Semiconductor in 2016; its legacy logic families remain widely supported in industrial and aerospace designs.

The 74ACQ244PC belongs to Fairchild's Quiet Series™ logic product line, engineered specifically for high-density PCBs where simultaneous switching noise and dynamic threshold instability compromise signal integrity in bus and clock distribution networks.

FAQ

What is the operating voltage range for the 74ACQ244PC?

The 74ACQ244PC operates from 2.0V to 6.0V, enabling interoperability between 3.3V and 5V logic systems. This wide VCC range is specified in the Absolute Maximum Ratings and Recommended Operating Conditions tables of the Fairchild datasheet DS010235, with full DC and AC performance guaranteed across the entire span.

Does the 74ACQ244PC support independent 3-STATE control for each group of outputs?

Yes, the 74ACQ244PC features two separate 3-STATE enable inputs: OE1 (pin 1) controls outputs O0–O3, and OE2 (pin 19) controls outputs O4–O7. This allows segmented bus control - for example, enabling one memory bank while disabling another - without requiring external logic or multiplexing.

How does the Quiet Series™ technology in the 74ACQ244PC reduce noise?

The 74ACQ244PC integrates Fairchild's Quiet Series™ architecture, which combines GTO™ output control, undershoot correction circuitry, and a split ground bus. These features collectively suppress simultaneous switching noise (SSN), limiting VOLP to ≤1.5 V and VOLV to ≥−1.2 V during worst-case transitions, as measured per Figure 1 test methodology.

What is the maximum output skew specification for the 74ACQ244PC?

The 74ACQ244PC guarantees ≤1.5 ns output-to-output skew (tOSHL/tOSLH) at 5.0V, defined as the absolute difference between propagation delays of any two outputs switching in the same direction. This parameter is guaranteed by design and verified per Note 14 in the AC Electrical Characteristics table.

Is the 74ACQ244PC pin-compatible with standard 74AC244 devices?

Yes, the 74ACQ244PC shares identical pinout, package dimensions (PDIP-20, JEDEC MS-001), and logic function with the 74AC244PC. However, it adds Quiet Series™ enhancements - including GTO™ control and split ground - without altering pin assignment or electrical interface, enabling drop-in replacement where noise reduction is critical.