Texas Instruments SN74BCT652DWR

Overview

SN74BCT652DWR from Texas Instruments is an octal bus transceiver and register IC with 3-state outputs, designed for bidirectional data flow control between two 8-bit buses (A and B). It integrates D-type flip-flops, independent clock/enable/select controls per bus, and real-time/stored data multiplexing. Key confirmed parameters: 5 V nominal supply, 77 MHz max clock frequency, 0°C to 70°C operating range, 128 mA low-level output current, and SOIC-24 (DW) package.

For engineers reviewing the SN74BCT652DWR datasheet, SN74BCT652DWR pinout, SN74BCT652DWR application, or SN74BCT652DWR equivalent, this page delivers verified functional architecture, timing-critical switching characteristics, bus-isolation behavior under OE control, and validated alternative options for legacy TTL-compatible bus management in industrial control backplanes and memory-mapped I/O systems.

Technical Context

The SN74BCT652DWR implements dual independent 8-bit transceiver paths with integrated storage registers, enabling simultaneous or selective latching of A- or B-bus data on rising clock edges. Its select-control logic eliminates decoding glitches during transitions between real-time and stored data modes - a critical feature for glitch-free bus arbitration.

Each bus path features dedicated OEAB/OEBA (output enable), SAB/SBA (select), and CLKAB/CLKBA (clock) inputs. Real-time transfer occurs when SAB/SBA = L; stored-data transfer when SAB/SBA = H. Power-up default places outputs in high-impedance state, preventing bus contention during system initialization.

Key Specifications

Pinout & Package

SN74BCT652DWR is housed in a 24-pin SOIC (DW) package with 300-mil width, surface-mount compatible, and RoHS-compliant with NiPdAu lead finish. Pin pitch is 1.27 mm; body dimensions are 15.4 mm × 7.5 mm × 2.35 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74BCT652DWR, SN74ACT652N trades drive strength and speed for lower static power, while 74F652PC retains TTL compatibility but sacrifices both speed and select-glitch immunity - making SN74BCT652DWR the optimal choice for new designs requiring robust 77 MHz bus throughput with deterministic arbitration behavior.

Availability

SN74BCT652DWR is available at Aetrix Electronics and suitable for industrial backplane bus arbitration, memory-mapped I/O interfaces, and legacy system data buffering requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74BCT652DWR 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 solutions for industrial, automotive, and communications markets.

The SN74BCT652DWR belongs to TI's BCT (Bipolar-CMOS Transceiver) logic family, engineered specifically for high-speed, high-drive 5 V bus interfacing in systems where TTL compatibility, noise immunity, and glitch-free control are mandatory design requirements.

FAQ

What is the maximum clock frequency supported by SN74BCT652DWR?

The SN74BCT652DWR supports a maximum clock frequency of 77 MHz under recommended operating conditions (VCC = 5 V, TA = 25°C). This value is confirmed in the timing requirements table of the official datasheet (SCBS038A, November 1993 revision) and applies to both CLKAB and CLKBA inputs. At temperature extremes within 0°C to 70°C, derating may apply, but the device remains fully functional up to its rated specification.

Does SN74BCT652DWR support true bidirectional data flow without external direction control?

Yes, SN74BCT652DWR enables true bidirectional data flow through independent OEAB and OEBA inputs - each controlling one direction (A↔B) separately. Unlike simple transceivers, it does not require an external direction pin; instead, output enables are asserted per path, allowing simultaneous or asymmetric activation. This architecture eliminates external logic for direction management in systems like dual-CPU shared-memory interconnects.

How does the glitch-free select logic in SN74BCT652DWR improve system reliability?

The glitch-free select logic in SN74BCT652DWR prevents transient output corruption during transitions between real-time and stored-data modes - a known failure point in basic multiplexer-based bus switches. By eliminating decoding glitches on SAB/SBA edges, SN74BCT652DWR ensures deterministic bus states during arbitration, avoiding spurious writes or corrupted status reads in time-critical applications such as real-time motion control loops.

Can SN74BCT652DWR operate with a 3.3 V supply?

No, SN74BCT652DWR is not rated for 3.3 V operation. Its absolute maximum supply voltage is 7 V, but the recommended operating range is strictly 4.5 V to 5.5 V. The input thresholds (VIH = 2 V, VIL = 0.8 V) and output drive characteristics are optimized for 5 V TTL compatibility. Using 3.3 V risks insufficient noise margin, degraded switching performance, and potential functional failure - a 3.3 V design requires a different logic family such as SN74LVC652.

What is the purpose of the NC pins in the SN74BCT652DWR DW package?

The SN74BCT652DWR in the DW (SOIC-24) package has no NC (No Connect) pins - all 24 pins are assigned functional roles as defined in the pinout diagram (pins 1–24: CLKAB, SAB, OEAB, A1–A8, GND, VCC, CLKBA, SBA, OEBA, B1–B8). NC pins appear only in the FK (ceramic chip carrier) variant (e.g., pins 3, 12, 25), not in the DW package used by SN74BCT652DWR. Confusion may arise from cross-package diagrams, but the DW layout is fully utilized.