Texas Instruments SN74LVC2952ANSR

Overview

SN74LVC2952ANSR from Texas Instruments is an octal bus transceiver and register with 3-state outputs, designed for bidirectional data flow between two 8-bit buses under independent clock control. It operates from 1.65 V to 3.6 V, supports 5.5-V-tolerant inputs, delivers 8.2 ns max propagation delay at 3.3 V, and features Ioff partial-power-down protection. It enables mixed-mode 3.3-V/5-V system interfacing in memory expansion and processor bus isolation applications.

For engineers reviewing the SN74LVC2952ANSR datasheet, SN74LVC2952ANSR pinout, SN74LVC2952ANSR application, or SN74LVC2952ANSR equivalent, this page provides verified functional role, timing behavior, voltage translation capability, Ioff-enabled power sequencing support, and SSOP-24 package–specific layout guidance - all critical for bus arbitration, level-shifting, and hot-swap–capable board design.

Technical Context

The SN74LVC2952ANSR integrates two independent 8-bit back-to-back registers: one latches A-bus data on CLKAB's low-to-high transition when CLKENAB is low, the other latches B-bus data on CLKBA's low-to-high transition when CLKENBA is low. Output-enable signals OEAB and OEBA independently control 3-state drive on each port.

Its dual-register architecture enables synchronous, edge-triggered data capture in both directions without bus contention. Input tolerance up to 5.5 V and Ioff circuitry allow safe operation during partial power-down or voltage-ramp mismatches between interconnected subsystems.

Key Specifications

Pinout & Package

SN74LVC2952ANSR is housed in a 24-pin SSOP (Shrink Small Outline Package) with 0.65-mm lead pitch, 7.9 mm × 5.3 mm body size, and 1.2 mm max height - optimized for high-density PCB layouts requiring thermal efficiency and reflow compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC2952ADBR, the SN74LVC2952ANSR offers identical functionality and timing but differs in reel packaging configuration and marking; compared with SN74LVC245APWR, it adds critical synchronous register capability enabling deterministic data capture in time-critical bus arbitration and modular system synchronization.

Availability

SN74LVC2952ANSR is available at Aetrix Electronics and suitable for processor bus isolation, memory expansion interfaces, hot-swappable module backplanes, industrial PLC I/O subsystems, and mixed-voltage embedded interconnects requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SN74LVC2952ANSR 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 high-reliability interface and power management ICs.

The SN74LVC2952ANSR belongs to TI's LVC logic family, engineered for low-voltage, high-speed bidirectional bus interfacing in mixed-signal systems - emphasizing voltage translation, power sequencing robustness, and precise timing control.

FAQ

What is the primary function of the SN74LVC2952ANSR in a digital system?

The SN74LVC2952ANSR functions as an octal bus transceiver with integrated dual-directional registers and 3-state outputs. It enables synchronized, bidirectional data transfer between two 8-bit buses using independent clock and enable controls. Its core purpose is to isolate, buffer, and translate signals across voltage domains (e.g., 3.3-V CPU ↔ 5-V peripheral) while providing edge-triggered latching for deterministic timing - making it essential in processor expansion, memory interfacing, and modular backplane architectures where bus contention and voltage mismatch must be managed.

Does the SN74LVC2952ANSR support operation at 2.5 V VCC?

Yes, the SN74LVC2952ANSR is fully specified for operation across 1.65 V to 3.6 V VCC, including 2.5 V. At 2.5 V, its typical VOL is 0.7 V (IOL = 8 mA), VOH is 1.7 V (IOH = –8 mA), and maximum propagation delay is 8.8 ns - all within guaranteed specifications. This allows seamless integration into 2.5-V logic domains while retaining 5.5-V input tolerance and Ioff protection, ensuring compatibility with mixed-supply systems without level-shifting components.

How does the Ioff feature of the SN74LVC2952ANSR improve system reliability?

The Ioff feature in the SN74LVC2952ANSR disables output drivers when VCC = 0 V, limiting leakage current to ±10 µA even if A- or B-bus signals remain at 5.5 V. This prevents destructive backflow current during power sequencing, hot-swap events, or partial system shutdown - a critical requirement in modular PLCs, telecom line cards, and industrial backplanes. Unlike standard 3-state devices, SN74LVC2952ANSR maintains safe high-impedance isolation regardless of VCC state, eliminating risk of latch-up or damage to powered subsystems.

Can the SN74LVC2952ANSR replace a standard 74LVC245 in existing designs?

No, the SN74LVC2952ANSR cannot directly replace a 74LVC245 because it implements a fundamentally different architecture: the SN74LVC2952ANSR includes dual 8-bit registers with separate clock and clock-enable inputs (CLKAB/CLKENAB, CLKBA/CLKENBA), whereas the 74LVC245 is a non-registering transceiver controlled only by direction (DIR) and output-enable (OE) pins. Replacing it would require redesigning clock distribution, removing latching logic, and accepting loss of synchronous data capture - making it unsuitable as a drop-in substitute unless the original design intentionally underutilized the SN74LVC2952ANSR's register capability.

What is the recommended power-up sequence for the SN74LVC2952ANSR to ensure high-impedance outputs?

To guarantee high-impedance outputs during power-up, OEAB and OEBA must be held high (inactive) until VCC stabilizes. TI recommends tying OEAB and OEBA to VCC through pull-up resistors; minimum resistance is determined by the driver's current-sinking capability - typically 4.7 kΩ suffices for most microcontroller-driven systems. This ensures outputs remain in 3-state before internal logic initializes, preventing bus conflicts or unintended data writes during power ramp. The Ioff feature further protects against bus contention if VCC rises after A/B bus signals are already active.