Texas Instruments SN74HCT652DWR

Overview

SN74HCT652DWR 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 SN74HCT652DWR datasheet, SN74HCT652DWR pinout, SN74HCT652DWR application, or SN74HCT652DWR equivalent, key selection criteria include dual-clock edge-triggered D-type registers, independent OEAB/OEBA and SAB/SBA controls, TTL-compatible inputs, and SOIC-24 package compatibility with LSTTL load driving (up to 15 loads).

Technical Context

The SN74HCT652DWR integrates eight identical bidirectional channels, each with a D-type flip-flop, multiplexed real-time/stored data path, and independent 3-state output enable. Its CLKAB/CLKBA inputs trigger low-to-high edge storage of A- or B-bus data regardless of OE or S states.

Select-control inputs SAB and SBA determine data source: low selects real-time pass-through, high selects registered output. OEAB and OEBA independently disable A→B or B→A transceiver paths into high-impedance, enabling bus isolation without affecting register state.

Key Specifications

Pinout & Package

SN74HCT652DWR uses a 24-pin SOIC (DW) package with 1.27-mm pitch, 7.5-mm body width, and moisture sensitivity level 1 (260°C peak reflow). Pin 1 is located in quadrant Q1 per tape-and-reel orientation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT652DWR, SN74HCT640DWR omits all register and select-control logic - reducing cost and complexity but removing data staging capability; SN74ACT543DW offers faster timing and stronger drive but sacrifices bidirectional flexibility and independent bus storage, limiting use to fixed-direction applications.

Availability

SN74HCT652DWR is available at Aetrix Electronics and suitable for industrial backplane interfacing, legacy system data buffering, automated test equipment signal routing, redundant control bus arbitration, and embedded microcontroller bus extension requiring stable component supply and long-term lifecycle support.

Supply support for SN74HCT652DWR 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 over 50 years of innovation in industrial-grade logic families.

The SN74HCT652DWR belongs to TI's HCT logic product line, designed specifically for 5-V systems requiring TTL-input compatibility, low power, and robust noise immunity in harsh industrial environments.

FAQ

What is the function of the SAB and SBA pins on the SN74HCT652DWR?

The SAB and SBA pins on the SN74HCT652DWR are select-control inputs that determine whether data transferred between buses is real-time (low) or sourced from internal D-type flip-flop registers (high). For example, when SAB = high, A→B transfers use stored A-bus data rather than live signals - enabling glitch-free handshaking in synchronous systems. This behavior is confirmed in the device's function table and logic diagram.

Can the SN74HCT652DWR operate reliably at 4.5 V supply voltage?

Yes, the SN74HCT652DWR is fully specified for operation from 4.5 V to 5.5 V per its recommended operating conditions. At 4.5 V, it maintains guaranteed VOH ≥ 3.7 V (with 6-mA sink), VOL ≤ 0.33 V, and tpd ≤ 37 ns (CL = 50 pF), meeting TTL interface requirements. These parameters are verified in the electrical characteristics and switching characteristics tables of the official datasheet.

How does the SN74HCT652DWR handle power-up sequencing to avoid bus contention?

To ensure high-impedance outputs during power-up or power-down, the SN74HCT652DWR datasheet specifies tying OEBA to VCC via a pullup resistor and OEAB to GND via a pulldown resistor. The minimum resistor value depends on driver current capability - this configuration prevents unintended bus driving before control logic stabilizes, avoiding contention on shared A/B buses.

Is the SN74HCT652DWR pin-compatible with other 24-pin SOIC octal transceivers like the SN74HCT245?

No, the SN74HCT652DWR is not pin-compatible with the SN74HCT245. While both use SOIC-24 packages, SN74HCT652DWR has dedicated CLKAB/CLKBA, SAB/SBA, and dual OE inputs occupying pins that SN74HCT245 uses for direction control (DIR) and single OE. Pin mapping differs fundamentally due to integrated register functionality - verified by comparing top-view pinouts in TI's SCLS179D and SCAS217 datasheets.

What is the maximum capacitive load the SN74HCT652DWR can drive while maintaining specified timing?

The SN74HCT652DWR is characterized for CL = 50 pF and CL = 150 pF loads. At 5.5 V, tpd increases from 31 ns (50 pF) to 50 ns (150 pF); setup/hold times also scale accordingly. Driving beyond 150 pF risks violating timing margins - TI recommends limiting total trace + load capacitance to ≤150 pF unless derating is applied per the switching characteristics tables in SCLS179D.