Texas Instruments CD74HCT368M

Overview

CD74HCT368M from Texas Instruments is a high-speed CMOS hex inverting buffer/line driver with three-state outputs, designed for bus interface applications requiring 5 V LSTTL-compatible logic levels, ±4 mA output drive, and operation across –55°C to 125°C. It features dual independent three-state enables (OE1 controls four channels; OE2 controls two), 11 ns typical propagation delay at VCC = 5 V and CL = 15 pF, and supports high-fanout bus driving up to 15 LSTTL loads.

For engineers reviewing the CD74HCT368M datasheet, CD74HCT368M pinout, CD74HCT368M application, or CD74HCT368M equivalent, this device is selected for robust 5 V digital bus buffering where level-shifting compatibility, wide temperature resilience, and controlled output enable sequencing are critical - especially in industrial control backplanes and legacy TTL-interfaced instrumentation.

Technical Context

The CD74HCT368M implements six independent inverting buffer stages, each with high-current CMOS output drivers capable of sourcing/sinking ±4 mA at VOH/VOL specifications. Its HCT logic family ensures direct compatibility with standard LS-TTL inputs (VIH ≥ 2.0 V, VIL ≤ 0.8 V) while maintaining CMOS power efficiency (ICC ≤ 160 μA over full temperature range).

Two separate three-state enable inputs (1OE on Pin 1, 2OE on Pin 15) provide granular bus control: OE1 governs Y1–Y4 outputs (Pins 3, 5, 7, 10), and OE2 governs Y5–Y6 (Pins 11, 13). This architecture enables partial bus isolation without disabling all channels simultaneously - essential for multi-master arbitration and hot-swap signaling paths.

Key Specifications

Pinout & Package

CD74HCT368M is supplied in a 16-pin SOIC (D) package with nominal body size 9.90 mm × 3.90 mm and standard JEDEC MS-012AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT368N and CD74HCT368E, CD74HCT368M offers optimized surface-mount manufacturability via SOIC-D tape-and-reel delivery, lower profile (1.75 mm max height), and tighter thermal coupling for thermally sensitive mixed-signal boards - making it the preferred choice for modern high-volume SMT production.

Availability

CD74HCT368M is available at Aetrix Electronics and suitable for industrial control backplanes, automotive diagnostic interfaces, military data acquisition systems, and automated test equipment requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD74HCT368M 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 connectivity solutions for industrial, automotive, and communications markets.

CD74HCT368M belongs to TI's legacy high-speed CMOS logic portfolio, engineered specifically for robust 5 V bus interfacing in harsh-environment systems where LSTTL compatibility, wide temperature operation, and three-state controllability are mandatory.

FAQ

What logic family does CD74HCT368M belong to, and why does that matter for system design?

CD74HCT368M belongs to the HCT (High-Speed CMOS TTL-compatible) logic family. This means it accepts standard LS-TTL input voltage thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) while delivering CMOS-level power efficiency and noise immunity. For system designers, this eliminates level-shifting circuitry when interfacing with legacy 74LS devices - reducing BOM cost, board area, and signal-integrity risk in mixed-logic upgrades.

How does the dual-enable architecture of CD74HCT368M improve bus management compared to single-enable buffers?

The CD74HCT368M uses two independent active-low enables: 1OE controls Y1–Y4, and 2OE controls Y5–Y6. This allows partial bus isolation - for example, holding Y5–Y6 in high-Z while actively driving Y1–Y4 during arbitration or fault recovery. In contrast, single-enable buffers force all six outputs into three-state simultaneously, limiting flexibility in multi-segment bus architectures and increasing contention risk during state transitions.

Can CD74HCT368M operate reliably at 125°C, and what design considerations support that rating?

Yes, CD74HCT368M is fully specified from –55°C to +125°C per its Recommended Operating Conditions. To sustain operation at 125°C, designers must limit junction temperature using the SOIC package's RθJA = 73°C/W: keep power dissipation below ~17 mW (e.g., <1 MHz toggle rate with 50 pF load), ensure adequate copper pour on VCC/GND planes, and place the device away from other heat sources. TI's datasheet confirms all electrical parameters remain valid across this full range.

What is the maximum capacitive load CD74HCT368M can drive while maintaining its 11 ns typical propagation delay?

The 11 ns typical propagation delay for CD74HCT368M is measured at CL = 15 pF and VCC = 5 V. As load capacitance increases, tpd degrades linearly: at CL = 50 pF, tpd rises to 30 ns (max) per datasheet Table 5.5. For designs requiring ≤15 ns delay, total net capacitance - including trace, stub, and receiver input - must be held ≤20 pF. Use series termination or reduce fanout to maintain timing margins in high-speed bus implementations.

Is CD74HCT368M pin-compatible with non-inverting variants like CD74HCT367M, and what changes are needed in layout or firmware?

Yes, CD74HCT368M is pin-compatible with CD74HCT367M - both use identical SOIC-16 pinouts and share the same dual-OE architecture. The sole functional difference is inversion: CD74HCT368M outputs are inverted relative to inputs, while CD74HCT367M outputs are non-inverted. Firmware must invert expected logic states on receiving ends; no PCB layout change is required, but signal integrity validation should confirm setup/hold timing remains intact after polarity reversal.