Texas Instruments CD74HCT244ME4

Overview

CD74HCT244ME4 from Texas Instruments is a non-inverting octal buffer/line driver with three-state outputs and dual active-low output enables, designed for bidirectional bus interfacing in 5-V digital systems. It delivers 8ns typical propagation delay at V_CC = 5 V, CL = 15 pF, supports ±25 mA output drive per channel, operates across –55°C to +125°C, and features LSTTL-compatible inputs (V_IL ≤ 0.8 V, V_IH ≥ 2 V).

For engineers reviewing the CD74HCT244ME4 datasheet, CD74HCT244ME4 pinout, CD74HCT244ME4 application, or CD74HCT244ME4 equivalent, this page provides verified electrical characteristics, package mapping to SOIC-20, functional pin definitions, real-world use cases in industrial bus buffering and microcontroller I/O expansion, and validated alternative parts with documented differences.

Technical Context

The CD74HCT244ME4 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 shared-bus arbitration without external logic.

Its HCT logic family ensures direct compatibility with TTL input thresholds while maintaining CMOS power efficiency. Input leakage remains ≤ ±1 μA at V_CC = 5.5 V, and three-state leakage is ≤ ±5 μA over full temperature range, supporting reliable bus hold and hot-swap conditions.

Key Specifications

Pinout & Package

CD74HCT244ME4 is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package with nominal body size 12.80 mm × 7.50 mm and standard 1.27-mm pitch. This surface-mount package supports automated assembly and offers thermal resistance R_θJA = 109.1°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT244N and 74ACT244PC, CD74HCT244ME4 offers optimal balance of industrial temperature range, proven noise immunity, SOIC packaging for production scalability, and seamless TTL interoperability - making it the preferred choice for robust, volume-manufactured embedded systems.

Availability

CD74HCT244ME4 is available at Aetrix Electronics and suitable for industrial bus buffering, microcontroller I/O expansion, legacy system interface, and test equipment signal conditioning requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD74HCT244ME4 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 specializing in analog, embedded processing, and logic solutions, with decades of heritage in high-reliability logic families.

CD74HCT244ME4 belongs to TI's CD74HCT high-speed CMOS logic series, engineered specifically for robust 5-V bus interfacing in industrial, aerospace, and automotive applications where temperature resilience and TTL compatibility are mandatory.

FAQ

What is the maximum output current per pin for CD74HCT244ME4?

The CD74HCT244ME4 supports ±25 mA DC output current per pin under recommended operating conditions (V_CC = 4.5 V to 5.5 V, T_A = –55°C to +125°C). This rating ensures reliable drive of 15 LSTTL loads or termination resistors without thermal derating in standard SOIC-20 layout. Exceeding ±25 mA risks violating absolute maximum ratings and may cause permanent damage to CD74HCT244ME4.

Does CD74HCT244ME4 require external pull-up resistors on its inputs?

No, CD74HCT244ME4 does not require external pull-up resistors on its inputs. Its HCT logic family features TTL-compatible input thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) and input leakage ≤ ±1 μA at V_CC = 5.5 V, allowing direct connection to open-collector or floating sources only when explicitly designed for high-impedance detection. For unused inputs, tie to V_CC or GND per TI layout guidelines - never leave floating. This applies to all pins of CD74HCT244ME4.

Can CD74HCT244ME4 operate at 3.3 V?

No, CD74HCT244ME4 is not specified for 3.3-V operation. Its HCT family requires V_CC = 4.5 V to 5.5 V to guarantee TTL-compatible input thresholds and full output drive capability. At 3.3 V, CD74HCT244ME4 may fail to recognize standard TTL high inputs (VIH ≥ 2.0 V becomes marginal), and output VOH drops below 2.4 V - violating LSTTL interface requirements. Use CD74HC244 or SN74LVC244A for true 3.3-V compatibility.

What is the thermal resistance (R_θJA) of CD74HCT244ME4 in SOIC-20 package?

The junction-to-ambient thermal resistance (R_θJA) for CD74HCT244ME4 in the SOIC-20 (M) package is 109.1°C/W, as specified in the latest revision (SCHS167G, October 2022) of the official Texas Instruments datasheet. This value assumes standard JEDEC 2-layer board conditions. For sustained operation near maximum ambient temperature, ensure adequate copper pour and avoid stacking heat-generating components adjacent to CD74HCT244ME4.

How many output enable pins does CD74HCT244ME4 have, and what is their logic polarity?

CD74HCT244ME4 has two output enable pins: 1OE (pin 17) and 2OE (pin 19), both active-low. When either 1OE or 2OE is high, the corresponding group of four outputs (Y1–Y4 or Y5–Y8) enters high-impedance state. Both enables must be low to assert all eight outputs. This dual-enable architecture enables selective bus partitioning - a key design feature of CD74HCT244ME4 not found in single-enable alternatives.