Texas Instruments SN74BCT756DW

Overview

SN74BCT756DW from Texas Instruments is an octal buffer/driver IC with open-collector outputs, designed for memory address bus driving and clock distribution in 3-state systems. It operates at 4.5–5.5 V, supports 0°C to 70°C ambient, delivers 64 mA sink current per output, and features BiCMOS logic for low ICCZ quiescent current.

For engineers reviewing the SN74BCT756DW datasheet, SN74BCT756DW pinout, SN74BCT756DW application, or SN74BCT756DW equivalent, this page provides verified technical context, package mapping, timing parameters, functional alternatives, and supply-chain support for industrial bus interface design.

Technical Context

The SN74BCT756DW implements two independent 4-bit non-inverting buffer sections (1A1–1A4 / 2A1–2A4), each controlled by a dedicated active-low output-enable input (1OE / 2OE). Its open-collector outputs require external pull-up resistors and support wired-AND logic and bus arbitration.

BiCMOS fabrication enables TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2.0 V) while delivering CMOS-level power efficiency and 4.1 ns max tPHL propagation delay. The device is not internally latched and relies on synchronous enable control for 3-state operation.

Key Specifications

Pinout & Package

SN74BCT756DW uses a 20-pin SOIC (DW) package, 7.5 mm wide, 12.83 mm long, 2.65 mm max height, with 1.27 mm pitch and NIPDAU lead finish. Pin 1 is marked by a beveled corner and located at top-left when viewed from top with notch up.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal open-collector buffer applications.

Compared with SN74BCT757DW and SN74BCT760DW, the SN74BCT756DW offers the simplest enable architecture (single active-low OE per 4-bit group) and non-inverting signal path - ideal for straightforward address buffering where polarity preservation and minimal control logic are priorities.

Availability

SN74BCT756DW is available at Aetrix Electronics and suitable for memory address buffering, parallel bus interface, and clock distribution applications requiring stable component supply, long-term industrial availability, and RoHS-compliant packaging.

Supply support for SN74BCT756DW 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 SN74BCT756DW belongs to TI's BCT (Bipolar-CMOS Transistor) logic family, engineered to replace 74LS/74ALS devices with superior speed-power trade-offs and enhanced bus-driving capability in legacy digital systems.

FAQ

What is the function of the 1OE and 2OE pins on the SN74BCT756DW?

The 1OE and 2OE pins are active-low output-enable inputs that independently control the 3-state operation of the two 4-bit buffer sections. When pulled low, the corresponding Y outputs (1Y1–1Y4 or 2Y1–2Y4) become active and sink current; when high, those outputs enter high-impedance state. This allows selective bus access without requiring external gating logic. The SN74BCT756DW relies on these pins for precise timing-controlled bus arbitration.

Does the SN74BCT756DW support 3.3 V logic inputs?

No, the SN74BCT756DW is designed for 5 V operation and has TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max). While a 3.3 V high-level signal may exceed VIH in some cases, it falls outside guaranteed operating conditions and risks marginal switching or increased noise susceptibility. For reliable 3.3 V interfacing, level-shifting circuitry or a 3.3 V–compatible buffer like SN74LVC8T245 is recommended. The SN74BCT756DW must be used with 5 V logic sources.

Can the SN74BCT756DW drive LED loads directly?

Yes - each open-collector output can sink up to 64 mA continuously, making the SN74BCT756DW suitable for direct LED driving with appropriate series current-limiting resistors. For example, with a 5 V supply and red LED (VF ≈ 1.8 V), a 51 Ω resistor limits current to ~63 mA. However, total package power dissipation must remain within thermal limits (θJA = 97°C/W), so simultaneous full-load operation across all eight outputs requires careful PCB thermal design. The SN74BCT756DW is commonly used this way in status indicator subsystems.

What is the maximum capacitive load the SN74BCT756DW can drive reliably?

The SN74BCT756DW is characterized for CL = 50 pF in switching specifications, with tPLH/tPHL values guaranteed up to that load. While it can drive higher capacitance (e.g., 100–150 pF) with degraded timing, signal integrity degrades beyond 75 pF due to increased rise/fall times and potential ringing. For loads >50 pF, series termination or reduced edge rate may be needed. The SN74BCT756DW's 64 mA sink capability supports moderate bus loading but is not optimized for heavy distributed capacitance.

Is the SN74BCT756DW pin-compatible with the SN74LS756N?

Yes - the SN74BCT756DW shares identical pinout, logic function, and DC electrical behavior with the SN74LS756N, including 20-pin SOIC/DIP compatibility and active-low OE control. It serves as a direct performance upgrade: same footprint, 3× faster propagation delay, 50% lower ICCZ, and higher output drive. No PCB changes are required when replacing SN74LS756N with SN74BCT756DW in existing designs.