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Home > Products > Integrated Circuits (ICs) > Logic > Buffers, Drivers, Receivers, Transceivers

Texas Instruments SN74ALS29861DWR

Name: SN74ALS29861DWR
Brand: Texas Instruments
SKU: SN74ALS29861DWR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74ALS29861DWR

Manufacturer:: Texas Instruments

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: -

Datasheet:: SN74ALS29861DWR.pdf

Description:: BUS TRANSCEIVER, ALS SERIES

Quantity:: RFQ Add To RFQ list

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Product details

Overview

SN74ALS29861DWR from Texas Instruments is a 10-bit non-inverting bus transceiver with dual enable controls (GAB and GBA), designed for asynchronous bidirectional data transfer between A and B buses in TTL-level systems. It supports true logic direction, features power-up high-impedance outputs, operates at 4.75–5.25 V, delivers ±24 mA/±48 mA output drive, and is rated for 0°C to 70°C ambient operation in industrial control backplanes.

For engineers reviewing the SN74ALS29861DWR datasheet, SN74ALS29861DWR pinout, SN74ALS29861DWR application, or SN74ALS29861DWR equivalent, key selection criteria include bidirectional bus isolation timing (tPZH/tPLZ ≤ 15 ns @ 50 pF), latch functionality (L/L input state), and compatibility with legacy ALS logic families in legacy computing and instrumentation designs.

Technical Context

The SN74ALS29861DWR implements dual independent enable logic: GAB enables A→B transmission while GBA enables B→A transmission; both high simultaneously isolate buses, both low latch A and B buses to identical states. Its internal architecture uses bipolar ALS (Advanced Low-Power Schottky) technology, delivering faster switching than standard LS logic while maintaining TTL-compatible voltage thresholds.

Timing behavior is defined by three-state enable/disable delays (tPZH/tPZL/tPHZ/tPLZ) and propagation delays (tPLH/tPHL) across multiple load conditions (5 pF, 50 pF, 300 pF). The device exhibits no internal bus contention due to mutually exclusive enable logic and includes input clamp diodes for VIK = −1.2 V protection.

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	4.75 V to 5.25 V - Ensures stable operation under standard TTL supply tolerances without brownout or overvoltage stress.
IOH / IOL	−24 mA / +48 mA - Supports driving multiple TTL inputs or moderate PCB trace capacitance without signal degradation.
tPLH / tPHL	4.0 ns to 15 ns (CL = 5–300 pF) - Enables reliable high-speed bus handshaking in 8/16-bit microprocessor peripheral interfaces.
VIH / VIL	2.0 V / 0.8 V - Matches standard TTL input thresholds, ensuring interoperability with 74LS, 74ALS, and 74F logic families.
Operating Temp	0°C to 70°C - Qualified for commercial-grade embedded systems including test equipment and industrial controllers.
ICC (max)	65 mA - Predictable power budgeting for multi-device bus interface assemblies with thermal margin.
VIK	−1.2 V - Provides negative transient immunity on data lines, reducing need for external clamping in noisy environments.

Pinout & Package

SN74ALS29861DWR is housed in a 24-pin SOIC (DW) package with 300-mil body width and gull-wing leads. Pin 1 is marked by a beveled corner; pins are numbered counter-clockwise from top-left when viewed from top with marking dot oriented top-left.

Pin/Terminal	Circuit Role	Design Meaning
1, 24	GAB, GBA	Active-low bidirectional bus enable controls: GAB = A→B, GBA = B→A; both high = isolation, both low = latch.
2–11, 14–23	A1–A10, B1–B10	10-bit parallel I/O ports - electrically isolated when enables inactive; support hot-swap-capable bus partitioning.
12	GND	Ground reference for all logic and output stages; requires low-inductance connection to minimize ground bounce.
13	VCC	Positive supply rail; decoupling capacitor (0.1 µF ceramic) required within 10 mm of this pin for noise suppression.

Key Features

Feature	Design Value
True Logic Direction	Non-inverting data path ensures A-to-B and B-to-A transmission preserves signal polarity without external inversion logic.
Power-Up High-Z	Outputs enter high-impedance state at power-on reset, preventing bus contention during system initialization sequences.
Latch Function	Simultaneous low on GAB and GBA captures and holds current A/B bus states, enabling transparent data snapshot capability.
Bidirectional Isolation	Independent enable controls allow asymmetric bus gating - e.g., A→B active while B→A disabled - for half-duplex arbitration.
ALS Process Compatibility	Optimized for 4.75–5.25 V operation with 24 mA sink/source, enabling drop-in replacement for 74ALS245 in legacy board upgrades.

Applications

Industrial Backplane Interface	Legacy Microprocessor Bus Extender
Use Scenario: Interfacing a Z80 CPU bus to peripheral I/O modules across a 12-inch PCB backplane with 30 pF/inch trace capacitance. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing address/data multiplexing and isolating CPU from peripheral loading effects. Use Value: Propagation delay ≤ 8 ns (CL = 50 pF) ensures setup/hold timing margins meet Z80's 250 ns bus cycle requirements.	Use Scenario: Adding ISA-compatible expansion slots to a custom 80286-based controller with separate local and expansion memory spaces. IC Role / Device Role / Timing Role: Direction-controlled data path enabling CPU read/write access to expansion cards while preventing bus conflicts during DMA cycles. Use Value: Independent GAB/GBA enables precise timing of bus ownership handoff, supporting 8 MHz ISA timing with <12 ns enable-to-output delay.
Test Equipment Signal Routing	Modular Instrumentation Data Mux
Use Scenario: Reconfigurable signal routing matrix in automated test equipment switching between DUT channels and measurement instruments. IC Role / Device Role / Timing Role: Programmable bus gate controlling data flow direction between instrument front-end and digitizer ASICs. Use Value: Latch mode (GAB=GBA=L) holds calibration data stable during instrument reconfiguration without host intervention.	Use Scenario: Multi-channel sensor aggregator consolidating analog-to-digital converter outputs onto a shared SPI-like parallel bus. IC Role / Device Role / Timing Role: Synchronized data capture buffer isolating ADC sampling clocks from host processor bus timing jitter. Use Value: Power-up high-Z prevents spurious data injection during cold start, eliminating need for external reset sequencing.

Industrial Backplane Interface

Legacy Microprocessor Bus Extender

Use Scenario: Interfacing a Z80 CPU bus to peripheral I/O modules across a 12-inch PCB backplane with 30 pF/inch trace capacitance.

IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing address/data multiplexing and isolating CPU from peripheral loading effects.

Use Value: Propagation delay ≤ 8 ns (CL = 50 pF) ensures setup/hold timing margins meet Z80's 250 ns bus cycle requirements.

Use Scenario: Adding ISA-compatible expansion slots to a custom 80286-based controller with separate local and expansion memory spaces.

IC Role / Device Role / Timing Role: Direction-controlled data path enabling CPU read/write access to expansion cards while preventing bus conflicts during DMA cycles.

Use Value: Independent GAB/GBA enables precise timing of bus ownership handoff, supporting 8 MHz ISA timing with <12 ns enable-to-output delay.

Test Equipment Signal Routing

Modular Instrumentation Data Mux

Use Scenario: Reconfigurable signal routing matrix in automated test equipment switching between DUT channels and measurement instruments.

IC Role / Device Role / Timing Role: Programmable bus gate controlling data flow direction between instrument front-end and digitizer ASICs.

Use Value: Latch mode (GAB=GBA=L) holds calibration data stable during instrument reconfiguration without host intervention.

Use Scenario: Multi-channel sensor aggregator consolidating analog-to-digital converter outputs onto a shared SPI-like parallel bus.

IC Role / Device Role / Timing Role: Synchronized data capture buffer isolating ADC sampling clocks from host processor bus timing jitter.

Use Value: Power-up high-Z prevents spurious data injection during cold start, eliminating need for external reset sequencing.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74ALS245N	Octal (8-bit), single-direction enable (OE), no latch mode; identical ALS process, same VCC/VIH/VIL.	Lacks dual-enable isolation and bus-latching; suitable only where unidirectional or simpler gating suffices.	Select when pin count or cost constraints eliminate need for 10-bit width or bidirectional flexibility.
AM29861PC	Functionally equivalent 10-bit transceiver; PDIP-24 package, same logic table and timing specs per AMD datasheet.	Same electrical behavior but different mechanical footprint; requires PCB layout change from SOIC to DIP.	Choose for through-hole prototyping or legacy repair where DW package soldering is impractical.

Compared with SN74ALS29861DWR, SN74ALS245N reduces channel count and removes latch capability but lowers cost and board space; AM29861PC matches function exactly but mandates through-hole assembly and lacks TI's long-term obsolescence documentation trail.

Availability

SN74ALS29861DWR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor bus extenders, and modular instrumentation data mux applications requiring stable component supply amid diminishing availability of mature logic devices.

Supply support for SN74ALS29861DWR 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 with broad industrial and automotive portfolio coverage.

The SN74ALS29861DWR belongs to TI's legacy 74ALS logic family, engineered for high-speed, low-power TTL-compatible bus interfacing in 1980s-era computing, instrumentation, and control systems.

FAQ

What is the logic function of SN74ALS29861DWR?

The SN74ALS29861DWR is a 10-bit bidirectional bus transceiver with independent GAB (A→B) and GBA (B→A) enables. When GAB is low and GBA high, data flows from A bus to B bus; when GBA is low and GAB high, data flows B→A; both high isolates buses; both low latches A and B to identical values. It implements true (non-inverting) logic only.

Does SN74ALS29861DWR support inverting logic modes?

No. The SN74ALS29861DWR provides true (non-inverting) logic only. Its functional equivalence to AM29861 confirms this; the inverting variant is the SN74ALS29862, which shares pinout and timing but inverts data paths. SN74ALS29861DWR must not be substituted with SN74ALS29862 without verifying system-level polarity requirements.

What package type is used for SN74ALS29861DWR?

SN74ALS29861DWR uses a 24-pin SOIC (Small Outline Integrated Circuit) package designated DW, with 300-mil body width, gull-wing leads, and standard JEDEC MS-013AC dimensions. Pin 1 is located at the top-left corner adjacent to the beveled edge or marking dot.

Is SN74ALS29861DWR still in production?

No. According to Texas Instruments' official packaging information, SN74ALS29861DWR is marked OBSOLETE - production has been discontinued. Aetrix Electronics supplies remaining authorized inventory with full traceability and offers engineering support for legacy design sustainment and last-time buy planning.

What are the absolute maximum ratings for SN74ALS29861DWR?

SN74ALS29861DWR has an absolute maximum VCC of 7 V, input voltage limit of 5.5 V on all pins, operating temperature range of 0°C to 70°C, and storage temperature range of −65°C to 150°C. Exceeding VCC > 7 V or VI > 5.5 V risks permanent damage; operation outside 0–70°C voids parametric guarantees.

SN74ALS29861DWR Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: *

Package/Case:: -

Packaging:: Bulk

Product Status:: Active

Logic Type:: -

Number of Elements:: -

Number of Bits per Element:: -

Input Type:: -

Output Type:: -

Current - Output High, Low:: -

Voltage - Supply:: -

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: -

Supplier Device Package:: -

SN74ALS29861DWR FAQ

1.How can I place an order for SN74ALS29861DWR through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74ALS29861DWR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SN74ALS29861DWR reliable?

The price and inventory of SN74ALS29861DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS29861DWR is usually 5 days.

3.What payment methods are accepted for SN74ALS29861DWR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS29861DWR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74ALS29861DWR?

SN74ALS29861DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74ALS29861DWR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SN74ALS29861DWR?

For technical support, including SN74ALS29861DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS29861DWR requirements.

6.How does Aetrix verify that SN74ALS29861DWR is sourced from the original manufacturer or authorized distributors?

All SN74ALS29861DWR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74ALS29861DWR meets industry standards.

7.What is the process for return or replacement of SN74ALS29861DWR?

All SN74ALS29861DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS29861DWR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SN74ALS29861DWR part is unused and in its original packaging.

Return procedure for SN74ALS29861DWR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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