Texas Instruments CD74ACT651M96E4

Overview

CD74ACT651M96E4 from Texas Instruments is a high-speed CMOS octal bus transceiver with 3-state outputs and non-inverting data paths, operating at 4.5–5.5 V supply, with typical propagation delay of 8.5 ns at V_CC = 5 V and 25 °C, used in bidirectional data bus isolation and level translation between TTL/CMOS logic domains.

For engineers reviewing the CD74ACT651M96E4 datasheet, CD74ACT651M96E4 pinout, CD74ACT651M96E4 application, or CD74ACT651M96E4 equivalent, key selection criteria include 3-state output control timing, bus-hold capability absence, SOIC-24 thermal performance, and compatibility with 5-V TTL input thresholds in mixed-voltage system interconnects.

Technical Context

This device implements dual 4-bit bidirectional transceivers (A↔B) with separate transmit/receive direction controls (1DIR/2DIR) and independent output enables (1OE/2OE), supporting simultaneous or independent bus flow. It uses ACT-series silicon for TTL-compatible inputs and CMOS outputs, ensuring fan-out of 50 LSTTL loads.

Logic levels conform to JEDEC Standard JESD8-A, with guaranteed high-level input voltage ≥ 2.0 V and low-level input voltage ≤ 0.8 V at V_CC = 5 V. Output drive strength is ±24 mA at V_CC = 5 V, enabling direct interface with standard 5-V logic without external pull-ups.

Key Specifications

Pinout & Package

CD74ACT651M96E4 is housed in a 24-pin SOIC (DW) package with 0.300-inch body width, 1.27-mm pitch, and JEDEC MS-013 compliant outline. Thermal resistance θ_JA is 90 °C/W (SOIC-24, 2-layer board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT245N and CD74ACT652M96, CD74ACT651M96E4 uniquely supports granular 4-bit directional control without added logic, making it optimal for space-constrained designs requiring independent arbitration of two 4-bit sub-buses.

Availability

CD74ACT651M96E4 is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy microprocessor bus extensions, and military data acquisition subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74ACT651M96E4 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial, automotive, and aerospace qualification.

CD74ACT651M96E4 belongs to TI's CD74ACT high-speed logic family, designed specifically for robust 5-V mixed-technology system interfacing where timing predictability, noise immunity, and extended temperature reliability are critical.

FAQ

What is the maximum clock frequency supported by CD74ACT651M96E4 in a bidirectional bus application?

CD74ACT651M96E4 does not operate on a clock signal-it is an asynchronous transceiver. Its usable data rate depends on propagation delay and system setup/hold timing. With 8.5 ns max t_PD, it supports reliable bidirectional toggling up to approximately 118 MHz in ideal conditions, assuming proper PCB routing and termination. Actual frequency in CD74ACT651M96E4 implementations is constrained by board-level signal integrity, not internal clocking.

Does CD74ACT651M96E4 include bus-hold or auto-direction-sensing circuitry?

No, CD74ACT651M96E4 has no bus-hold or auto-direction features. Direction is strictly controlled by the 1DIR and 2DIR inputs, and outputs enter high-impedance only when 1OE or 2OE is asserted high. External pull-up/down resistors or system-level control logic must manage floating bus states. This design choice preserves timing determinism and reduces quiescent current versus integrated bus-hold variants.

Can CD74ACT651M96E4 be used with 3.3-V logic systems?

CD74ACT651M96E4 is specified only for 4.5–5.5 V operation and lacks 3.3-V tolerant inputs. Its TTL-compatible input thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) may accept 3.3-V logic highs marginally, but DC parametric guarantees and noise margins are not assured below V_CC = 4.5 V. For 3.3-V interfacing, use purpose-built level translators such as TXB0108 or SN74LVC8T245 instead of CD74ACT651M96E4.

What is the recommended decoupling for CD74ACT651M96E4 in high-speed layouts?

TI recommends placing a 0.1 µF X7R ceramic capacitor between V_CC (pin 21) and GND (pin 24) as close as possible to the SOIC-24 package body-ideally within 3 mm trace length. For systems with multiple CD74ACT651M96E4 devices or high di/dt switching, add a bulk 4.7 µF tantalum or aluminum electrolytic capacitor per 5–10 ICs on the same 5-V rail. Avoid shared vias between decoupling caps and signal return paths.

Is CD74ACT651M96E4 RoHS compliant and lead-free?

Yes, CD74ACT651M96E4 is RoHS compliant and uses NiPdAu (NIPDAU) lead finish, per TI's packaging documentation. It carries MSL Level-1 rating (unlimited floor life at ≤30 °C/60% RH) and is compatible with standard Pb-free reflow profiles peaking at 260 °C. The "E4" suffix confirms TI's green packaging standard, including halogen-free molding compound and lead-free terminations.