Texas Instruments SN74HC652DW

Overview

SN74HC652DW from Texas Instruments is an octal bus transceiver and register IC with 3-state outputs, designed for bidirectional data routing and real-time/stored-data multiplexing between two 8-bit buses (A and B). It operates from 2 V to 6 V, delivers 11 ns typical propagation delay at 5 V, supports ±6-mA output drive, and features independent clock (CLKAB/CLKBA), select (SAB/SBA), and output-enable (OEAB/OEBA) controls for flexible bus management in industrial control and instrumentation systems.

For engineers reviewing the SN74HC652DW datasheet, SN74HC652DW pinout, SN74HC652DW application, or SN74HC652DW equivalent, key selection considerations include dual-register storage capability, simultaneous real-time and stored-data transfer modes, 24-pin SOIC package compatibility, and 3-state output isolation timing (ten = 61 ns max at 4.5 V, CL = 50 pF).

Technical Context

The SN74HC652DW integrates eight identical bidirectional channels, each combining a D-type flip-flop register, 3-state bus transceiver, and independent control logic. Real-time transfer occurs when SAB/SBA are low; stored-data transfer activates when high-enabling selective forwarding of latched A→B or B→A data without external logic.

Its dual-clock architecture allows asynchronous storage: CLKAB latches A-bus data into internal registers while CLKBA latches B-bus data, with OEAB/OEBA enabling/disabling output drivers independently. The device maintains high-impedance state during power sequencing via recommended pullup/pulldown on OEBA/OEAB.

Key Specifications

Pinout & Package

SN74HC652DW is housed in a 24-pin SOIC (DW) package with standard 0.300-inch body width and 1.27 mm pitch. Pin 1 is located at the top-left corner (Q1 quadrant per tape-and-reel specification), with GND at pin 12 and VCC at pin 13.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT652DW, the SN74HC652DW offers superior noise immunity in CMOS-only systems but requires level-shifting for direct TTL interface; versus 74AC652PC, it trades raw speed for integrated storage and flexible bus arbitration - making it optimal for deterministic data capture and routing architectures.

Availability

SN74HC652DW is available at Aetrix Electronics and suitable for industrial PLC backplane interfaces, test equipment data capture modules, legacy bus extenders, redundant control path managers, and embedded instrumentation requiring stable component supply across extended temperature ranges.

Supply support for SN74HC652DW 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 for industrial, automotive, and communications markets.

The SN74HC652DW belongs to TI's 74HC high-speed CMOS logic family, engineered for low-power, wide-voltage-range bus interface and data capture in deterministic real-time systems.

FAQ

What is the maximum clock frequency supported by the SN74HC652DW?

The SN74HC652DW supports a maximum clock frequency of 31 MHz at VCC = 4.5 V and TA = 25°C, as specified in the timing requirements table. This value decreases to 27 MHz over the full –40°C to 85°C operating range. The limit arises from internal propagation delays and setup/hold timing constraints for reliable register latching on CLKAB and CLKBA edges. Designers must verify timing margins against actual load capacitance and signal rise/fall times in their layout.

How does the SN74HC652DW handle power-up sequencing to avoid bus contention?

To prevent undefined states during power-up, the SN74HC652DW requires OEBA to be tied to VCC via a pullup resistor and OEAB to GND via a pulldown resistor. This ensures both output drivers remain in high-impedance mode until system firmware asserts valid control signals. The minimum resistor value depends on the driver's current-sinking/sourcing capability - typically 10 kΩ suffices for most microcontroller GPIOs. Failure to implement this may cause transient bus conflicts or excessive ICC surge.

Can the SN74HC652DW perform simultaneous A→B and B→A data transfers?

No - the SN74HC652DW cannot perform true simultaneous bidirectional transfers. Its functional table shows that when OEAB and OEBA are both low, the device enters "Stored A data to B bus and stored B data to A bus" mode, but this requires staggered clocks (CLKAB and CLKBA must not rise simultaneously when SAB = SBA = H). Real-time transfer in both directions is prohibited; attempting it causes bus contention. The IC is designed for controlled, time-multiplexed operation - not full-duplex concurrency.

What is the purpose of the NC (no-connect) pins on the SN74HC652DW SOIC package?

The SN74HC652DW DW-package pinout contains no NC (no internal connection) pins - all 24 pins are electrically assigned per the official TI datasheet. Earlier documentation referencing NC pins applies only to alternate packages (e.g., FK or JT variants), not the DW variant. Misidentifying pins as NC could lead to incorrect PCB layout or floating node errors. Always refer to the DW-specific pin diagram in SCLS151E Figure 1 for authoritative mapping.

Does the SN74HC652DW support hot-swap or live-insertion applications?

The SN74HC652DW is not rated for hot-swap operation. Its absolute maximum ratings do not specify I/O port survivability during partial power application, and the absence of bus-hold or Schmitt-trigger inputs increases susceptibility to intermediate voltage states during insertion. While its 3-state outputs provide isolation, uncontrolled VCC ramp rates or floating control inputs (OEAB/OEBA) during insertion can induce latch-up or excessive ICC. For hot-swap designs, dedicated hot-swap controllers or buffers with built-in protection should precede the SN74HC652DW.