Texas Instruments SN74HCT652DW

Overview

SN74HCT652DW from Texas Instruments is an octal bus transceiver and register IC with 3-state outputs, operating at 4.5 V to 5.5 V, delivering 12 ns typical propagation delay, ±6-mA output drive at 5 V, and low 80-µA max ICC. It enables bidirectional real-time or stored data transfer between two 8-bit buses in industrial control backplanes and legacy system upgrades.

For engineers reviewing the SN74HCT652DW datasheet, SN74HCT652DW pinout, SN74HCT652DW application, or SN74HCT652DW equivalent, this page provides verified functional architecture, validated timing behavior under 50-pF load, confirmed SOIC-24 package mapping, and direct alternatives for bus isolation and registered data routing in 5-V TTL-compatible systems.

Technical Context

The SN74HCT652DW integrates eight independent D-type flip-flops with dual clock inputs (CLKAB/CLKBA), dual select controls (SAB/SBA), and dual 3-state output enables (OEAB/OEBA) to support four distinct bus-management modes: real-time A↔B transfer, stored A↔B transfer, simultaneous A/B storage, and mixed hold/store operation. Its logic diagram confirms separate internal registers per bus, with no shared clock domain between A and B paths.

Each channel features true data path architecture-inputs are always enabled for register loading on CLK↑, while output enable is fully independent. The device exhibits TTL-voltage-compatible inputs (VIH = 2 V min, VIL = 0.8 V max at 4.5–5.5 V), and its 3-state outputs meet LSTTL drive capability (up to 15 loads), with guaranteed VOL ≤ 0.33 V at IOL = 6 mA and VOH ≥ 3.7 V at IOH = –6 mA.

Key Specifications

Pinout & Package

SN74HCT652DW is housed in a 24-pin SOIC (DW) package with standard 0.300-inch body width, gull-wing leads, and JEDEC MS-013AC outline. Pin 1 is located at the top-left corner (Q1 quadrant) when viewed from the top with the marking side up and the notch or dot oriented left.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT640DW, SN74HCT652DW adds essential register storage and independent bus control-critical for synchronous protocol bridging. Against SN74ACT652DW, it trades 3 ns speed for 2.5× lower quiescent current and superior noise immunity in electrically noisy industrial settings.

Availability

SN74HCT652DW is available at Aetrix Electronics and suitable for industrial backplane isolation, legacy system data registering, and automated test fixture control requiring stable component supply across extended production lifecycles.

Supply support for SN74HCT652DW 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 SN74HCT652DW belongs to TI's 74HCT logic family, designed specifically to provide TTL-compatible input thresholds and CMOS power efficiency in 5-V digital systems requiring registered bus interfacing.

FAQ

What is the maximum clock frequency supported by the SN74HCT652DW?

The SN74HCT652DW supports a maximum clock frequency of 22 MHz at VCC = 5.5 V and TA = 25°C with CL = 50 pF, as specified in the switching characteristics table. This limit derives from its 12 ns typical propagation delay and setup/hold timing margins. At 4.5 V, the rated fmax drops to 17 MHz. For reliable operation across the full –40°C to +85°C range, design margins should account for worst-case tpd = 31 ns and tsu = 19 ns.

How does the SN74HCT652DW handle power-up sequencing to avoid bus contention?

To ensure high-impedance outputs during power-up, the SN74HCT652DW datasheet specifies tying OEBA to VCC via a pull-up resistor and OEAB to GND via a pulldown resistor. This forces OEBA inactive (high) and OEAB active (low) at power-on, placing the B→A path in high-Z while enabling A→B isolation. Resistor values must respect the driver's current-sinking/source capability-typically 10 kΩ suffices given the ±1 µA input leakage.

Can the SN74HCT652DW operate with mixed voltage domains, such as 3.3-V inputs driving a 5-V bus?

No-the SN74HCT652DW is strictly a 5-V device with TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max) referenced to its own VCC rail. Applying 3.3-V logic signals directly violates the minimum VIH requirement at VCC = 5 V and risks unreliable switching or increased ICC. Level translation-e.g., using SN74LVC4245 or discrete resistive dividers-is required for interfacing with 3.3-V sources.

What is the function of the NC pins on the SN74HCT652DW SOIC package?

The SN74HCT652DW DW package has no NC (No Connect) pins-its 24-pin SOIC layout fully utilizes all positions per the official pin diagram. Pins 1–24 correspond directly to CLKAB, SAB, OEAB, A1–A8, GND, VCC, CLKBA, SBA, OEBA, and B1–B8. Any reference to NC in generic family diagrams applies only to other packages (e.g., NT or FK) and does not apply to the DW variant.

Is the SN74HCT652DW still in active production, and what is its lifecycle status?

The base part SN74HCT652DW is marked "Obsolete" in TI's packaging addendum, but the tape-and-reel variant SN74HCT652DWR.A remains Active with full production support, RoHS compliance, and Level-1 MSL rating. Aetrix Electronics stocks and distributes the active DWR.A version, ensuring long-term availability for new designs and legacy system maintenance through TI's announced product lifecycle policies.