Texas Instruments SN74BCT757DWE4

Overview

SN74BCT757DWE4 from Texas Instruments is an octal noninverting buffer/driver with complementary 3-state enable inputs and open-collector outputs, designed for memory address driving and bus interfacing. It operates at 4.5–5.5 V, supports 64 mA sink current per output, delivers 2.4 ns typical tPHL, and is rated for 0°C to 70°C operation.

For engineers reviewing the SN74BCT757DWE4 datasheet, SN74BCT757DWE4 pinout, SN74BCT757DWE4 application, or SN74BCT757DWE4 equivalent, key selection criteria include open-collector bus drive capability, BiCMOS low ICCZ quiescent current, dual active-low/active-high OE control, and SOIC-20 package compatibility with legacy 74-series logic layouts.

Technical Context

The SN74BCT757DWE4 implements a BiCMOS architecture that combines bipolar input stages for high-speed switching (tPHL down to 2 ns) with CMOS-like low standby current (ICCZ ≤ 10 mA). Its dual enable structure-1OE (active-low) and 2OE (active-high)-enables flexible bus arbitration in shared-line systems.

Each of the eight channels features open-collector outputs capable of sinking up to 64 mA at VOL ≤ 0.55 V, supporting wired-AND logic and direct interface to TTL/CMOS loads. Input thresholds are VIH ≥ 2.0 V and VIL ≤ 0.8 V, ensuring robust noise margin across 5-V systems.

Key Specifications

Pinout & Package

SN74BCT757DWE4 is housed in a 20-pin SOIC (DW) package with 1.27 mm pitch, 7.5 mm width, and 2.65 mm max height, compatible with standard surface-mount assembly processes and IPC-7351 land patterns.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS244N and SN74ACT244DW, the SN74BCT757DWE4 uniquely balances high sink current (64 mA), fast switching (2.4 ns tPHL), dual-OE control, and open-collector architecture-making it the only option among the three that supports true wired-AND bus arbitration without external components.

Availability

SN74BCT757DWE4 is available at Aetrix Electronics and suitable for memory address buffering, industrial bus interfacing, legacy system upgrades, and programmable controller I/O expansion requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74BCT757DWE4 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 delivering analog, embedded processing, and logic solutions with emphasis on reliability, longevity, and industrial-grade qualification.

The SN74BCT757DWE4 belongs to TI's 74BCT family of BiCMOS logic devices, engineered specifically to replace bipolar 74LS/74ALS buffers in high-density memory and bus systems where speed, power efficiency, and open-collector flexibility are critical.

FAQ

What is the function of the dual OE inputs on the SN74BCT757DWE4?

The SN74BCT757DWE4 features two complementary output-enable inputs: 1OE (active-low) and 2OE (active-high). When 1OE is LOW and 2OE is HIGH, all eight outputs are enabled in the active state. This dual-control scheme allows flexible integration into systems using either polarity of enable signaling-eliminating the need for external inverters and simplifying bus arbitration logic in multi-controller environments. The SN74BCT757DWE4 thus supports both legacy active-low and modern active-high control architectures without redesign.

Can the SN74BCT757DWE4 drive standard TTL loads directly?

Yes, the SN74BCT757DWE4 can directly drive standard TTL loads. Each open-collector output sinks up to 64 mA at VOL ≤ 0.55 V, exceeding the 16 mA sink requirement of a standard TTL input. With appropriate external pull-up (e.g., 1–4.7 kΩ to 5 V), the SN74BCT757DWE4 reliably interfaces with 74LS, 74ALS, and 74F families. Its VIH ≥ 2.0 V and VIL ≤ 0.8 V thresholds ensure full compatibility with TTL logic levels across temperature and voltage variations.

What is the maximum operating frequency supported by the SN74BCT757DWE4 in a bus-driving application?

The SN74BCT757DWE4 does not specify a maximum clock frequency, but its propagation delays determine usable edge rates: tPHL = 2.0–6.6 ns and tPLH = 6.6–10.1 ns (CL = 50 pF). In practice, this supports reliable operation in address/data bus applications up to ~50 MHz for setup/hold-critical paths and >100 MHz for less timing-sensitive control lines. Actual maximum frequency depends on load capacitance, pull-up strength, and system-level timing margins-not an intrinsic clock limit of the SN74BCT757DWE4 itself.

Is the SN74BCT757DWE4 RoHS compliant and lead-free?

Yes, the SN74BCT757DWE4 is RoHS compliant and features NiPdAu (NIPDAU) lead finish, as confirmed in TI's Packaging Information Addendum. It carries MSL Level-1 rating (unlimited floor life at ≤30°C/60% RH) and is qualified for lead-free reflow per JEDEC J-STD-020. The device meets EU RoHS Directive 2011/65/EU and TI's internal environmental standards, making it suitable for new designs requiring compliance with global environmental regulations.

How does the BiCMOS design of the SN74BCT757DWE4 improve system power efficiency?

The BiCMOS design of the SN74BCT757DWE4 reduces quiescent supply current (ICCZ) to ≤10 mA when outputs are disabled-over 75% lower than equivalent bipolar 74LS244 devices (~44 mA). This reduction occurs because CMOS input stages draw negligible DC current, while optimized bipolar output stages maintain high-speed switching. In systems with many idle buffers-such as memory subsystems during wait states-the SN74BCT757DWE4 significantly lowers total standby power without sacrificing performance or drive capability.