Texas Instruments CD74HC244E

Overview

CD74HC244E from Texas Instruments is a non-inverting octal buffer/line driver with three-state outputs and dual active-low output enables. It operates from 2 V to 6 V, delivers ±7.8 mA output drive at 6 V, exhibits 9 ns typical propagation delay (VCC = 4.5 V, CL = 15 pF), and supports industrial temperature range (–55°C to 125°C). It serves as a bus interface and data isolation device in microcontroller peripheral expansion systems.

For engineers reviewing the CD74HC244E datasheet, CD74HC244E pinout, CD74HC244E application, or CD74HC244E equivalent, key selection criteria include its dual active-low enable architecture, high-current bus-driver outputs (±7.8 mA), wide supply range (2–6 V), LSTTL-load fanout (15), and compatibility with HC logic families in mixed-voltage digital systems.

Technical Context

The CD74HC244E implements two independent 4-bit non-inverting buffer sections, each controlled by its own active-low output enable (1OE, 2OE). All eight outputs enter high-impedance state when either enable is asserted low - enabling bidirectional bus sharing without external direction control logic.

Its CMOS input structure provides high noise immunity (NIL/NIH = 30% of VCC at 5 V) and ultra-low input leakage (±1 μA max), while the buffered inputs and balanced transition times minimize skew across channels. The device shares identical pinout with CD74HC240 and CD74HC241, allowing layout reuse across inverting/non-inverting variants.

Key Specifications

Pinout & Package

CD74HC244E is supplied in a 20-pin plastic dual in-line package (PDIP, body size 25.40 mm × 6.35 mm), compatible with through-hole prototyping and legacy PCB assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC244N, CD74HC244E offers identical functionality but may have older date-code batches and less aggressive obsolescence monitoring; versus 74VHC244N, it trades speed for wider supply tolerance and higher drive - making it preferable for ruggedized industrial interfaces.

Availability

CD74HC244E is available at Aetrix Electronics and suitable for microcontroller I/O expansion, industrial bus interfacing, and memory address latching requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC244E 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

CD74HC244E belongs to TI's CD74HC high-speed CMOS logic family, designed specifically for robust, low-power digital interfacing in harsh-environment applications demanding wide temperature operation and high noise immunity.

FAQ

What is the maximum output current per pin for CD74HC244E?

The CD74HC244E delivers ±7.8 mA output sink/source current per pin at VCC = 6 V, as specified in the Electrical Characteristics table for '244 devices. This value ensures reliable driving of 15 LSTTL loads and supports direct connection to moderate-capacitance buses without external buffering. Exceeding this current risks violating VOL/VOH specifications or thermal limits.

Does CD74HC244E support 3.3 V operation?

Yes, CD74HC244E fully supports 3.3 V operation within its rated 2 V to 6 V supply range. At VCC = 3.3 V, it maintains valid VOH ≥ 2.5 V and VOL ≤ 0.55 V (per HC-type VIH/VIL and VOH/VOL specs), ensuring interoperability with standard 3.3 V logic families. Input thresholds scale proportionally, providing 30% noise margin.

How are the output enables configured on CD74HC244E?

CD74HC244E features two active-low output enables: 1OE controls outputs Y1–Y4, and 2OE controls outputs Y5–Y8. Both enables must be high (logic 1) for their respective outputs to drive; asserting either low places its four outputs in high-impedance state. This dual-enable architecture enables independent gating of two 4-bit data paths.

Can CD74HC244E replace CD74HC240 in a design?

No - CD74HC244E cannot directly replace CD74HC240 because they differ in logic function: CD74HC240 is inverting, while CD74HC244E is non-inverting. Although they share identical pinout and electrical specs, swapping them would invert all eight data bits. Functional replacement requires redesigning signal polarity handling or selecting CD74HC241 (non-inverting, mixed-enable) if pin compatibility is critical.

What is the typical propagation delay of CD74HC244E at 5 V?

The typical propagation delay of CD74HC244E is 9 ns at VCC = 4.5 V and CL = 15 pF, as stated in Section 5.9 Switching Characteristics '244. At exactly 5 V, interpolation from the 4.5 V and 6 V data points yields ~8.5–8.8 ns typical - consistent with the family's 8 ns typical spec cited in the Features section for HC240 under identical test conditions.