Texas Instruments CD74FCT244E

Overview

CD74FCT244E from Texas Instruments is a BiCMOS octal noninverting buffer/line driver with 3-state outputs in a 20-pin PDIP package, delivering 64-mA sink current per output, 3.7-V output voltage swing limit, and 5.25-V max supply voltage - used for bus isolation and data routing in industrial control backplanes.

For engineers reviewing the CD74FCT244E datasheet, CD74FCT244E pinout, CD74FCT244E application, or CD74FCT244E equivalent, key selection criteria include its 3-state enable timing (tdis = 7 ns max), BiCMOS EMI suppression via controlled edge rates, input/output isolation from V_CC, and compatibility with TTL-level logic systems operating at 4.75–5.25 V.

Technical Context

This device implements two independent 4-bit noninverting buffer sections, each with active-low output-enable (OE) control. The BiCMOS architecture combines bipolar pull-down and CMOS pull-up transistors to limit high-level output voltage to ~3.7 V (two diode drops below V_CC), reducing power-bus ringing and ground bounce during simultaneous switching.

Each output stage supports 64-mA sink current while maintaining VOL ≤ 0.55 V at that load, and features SCR latch-up-resistant design. Input clamping and thermal performance (θ_JA = 69°C/W for PDIP) are specified for reliable operation across 0°C to 70°C ambient.

Key Specifications

Pinout & Package

CD74FCT244E uses a 20-pin plastic dual in-line package (PDIP-N) with 0.3-inch body width and through-hole mounting. Pin 1 is identified by a notch or dot marking at the top-left corner of the package.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74F244N and 74ACT244PC, CD74FCT244E uniquely balances high sink current (64 mA), EMI-suppressing 3.7-V output swing, and BiCMOS speed/power trade-off - making it optimal for industrial backplanes requiring robust bus driving without added filtering.

Availability

CD74FCT244E is available at Aetrix Electronics and suitable for industrial automation, test equipment, and legacy system upgrades requiring stable component supply, long-term obsolescence management, and RoHS-compliant through-hole assembly.

Supply support for CD74FCT244E 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 for industrial, automotive, and communications markets.

The CD74FCT244E belongs to TI's 74FCT logic family - designed specifically for high-speed, low-noise 5-V digital interfacing in mission-critical industrial and instrumentation systems.

FAQ

What is the maximum allowable supply voltage for CD74FCT244E?

The absolute maximum DC supply voltage for CD74FCT244E is 6 V, but the recommended operating range is strictly 4.75 V to 5.25 V. Operating outside this window risks violating VOH/VOL specifications and may degrade the BiCMOS output stage's EMI-suppression behavior. The CD74FCT244E datasheet specifies all electrical characteristics at 5 V ± 0.25 V, and sustained use above 5.25 V voids parametric guarantees.

How does CD74FCT244E suppress electromagnetic interference compared to standard TTL buffers?

CD74FCT244E suppresses EMI by limiting its output high voltage to approximately 3.7 V - two diode drops below V_CC - which reduces dV/dt during switching and minimizes power-bus ringing. This BiCMOS design also features controlled edge rates and low ground bounce, unlike standard TTL buffers that swing full-rail (0–5 V) and generate stronger harmonic content. The CD74FCT244E's 35-pF power dissipation capacitance further contributes to predictable dynamic current draw.

Can CD74FCT244E drive standard TTL inputs reliably?

Yes, CD74FCT244E drives standard TTL inputs reliably: its VOH minimum is 2.4 V at –15 mA, exceeding TTL's 2.0-V VIH threshold, and its VOL maximum is 0.55 V at 64 mA, well below TTL's 0.8-V VIL limit. The CD74FCT244E's 64-mA sink capability also exceeds standard TTL's 16-mA fan-in requirement, supporting up to four standard TTL loads per output without degradation.

What is the correct power-up sequence to ensure CD74FCT244E outputs remain in high-impedance state?

To guarantee high-impedance outputs at power-up, tie both 1OE and 2OE pins (pins 1 and 19) to V_CC via pull-up resistors - minimum value determined by the driver's current-sinking capability (typically 10 kΩ). This prevents floating OE states that could cause unintended output activation during V_CC ramp-up. The CD74FCT244E's input/output isolation from V_CC ensures this strategy remains effective even if inputs become active before V_CC stabilizes.

Is CD74FCT244E compatible with 3.3-V logic systems?

CD74FCT244E is not 3.3-V logic compatible: its inputs require VIH ≥ 2.0 V and VIL ≤ 0.8 V referenced to a 5-V V_CC, and its outputs swing 0–3.7 V - insufficient to meet 3.3-V CMOS VIH (≥ 2.0 V) with margin under load. Direct connection to 3.3-V systems risks undriven inputs or marginal VOH. For mixed-voltage interfaces, use level-shifting logic or select a 3.3-V–tolerant alternative; the CD74FCT244E is optimized exclusively for 5-V TTL/CMOS environments.