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Texas Instruments SN74ALS29825DW

Name: SN74ALS29825DW
Brand: Texas Instruments
SKU: SN74ALS29825DW
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74ALS29825DW

Manufacturer:: Texas Instruments

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: -

Datasheet:: SN74ALS29825DW.pdf

Description:: BUS DRIVER, ALS SERIES

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Product details

Overview

SN74ALS29825DW from Texas Instruments is an 8-bit D-type edge-triggered flip-flop with three-state outputs, noninverting data inputs, and independent output control (OC1/OC2/OC3). It operates at 5 V, delivers ±24 mA output drive, supports 0°C to 70°C ambient, and is designed for bus-oriented systems requiring high-impedance isolation during multiuser register access.

For engineers reviewing the SN74ALS29825DW datasheet, SN74ALS29825DW pinout, SN74ALS29825DW application, or SN74ALS29825DW equivalent, key selection criteria include clock enable latching behavior, undershoot-protected outputs, power-up high-impedance state, and compatibility with legacy TTL bus architectures.

Technical Context

This device implements eight synchronous D-type flip-flops with gated clock enable (CLKEN) and asynchronous active-low clear (CLR), enabling precise data capture and retention independent of output state. Its buffered OC inputs decouple control logic from bus loading, while internal undershoot protection prevents negative voltage transients on outputs.

The SN74ALS29825DW uses Advanced Low-Power Schottky (ALS) bipolar technology, delivering faster propagation (tPLH/tPHL ≤ 10 ns at 5 V) and lower ICC (≤100 mA) than standard LS logic. Output enable logic is OR-based: any OC input low forces all Q outputs into high-impedance (Z), regardless of CLK or CLR state.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	Advanced Low-Power Schottky (ALS) TTL - ensures compatibility with 5 V TTL systems and improved speed-power tradeoff vs. standard LS.
Supply Voltage	4.75 V to 5.5 V - requires tightly regulated 5 V rail; operation outside this range risks functional failure or damage.
Output Drive	IOH = −24 mA / IOL = 48 mA - enables direct driving of heavily loaded buses (e.g., >10 TTL loads) without external buffers.
Propagation Delay	tPLH/tPHL ≤ 10 ns (VCC = 5 V, CL = 50 pF) - supports reliable operation in sub-100 MHz synchronous bus timing windows.
Input Thresholds	VIH = 2.0 V min / VIL = 0.8 V max - maintains noise margin against TTL-compatible signal sources and avoids false triggering.
Power-Up State	Outputs default to high-impedance - prevents bus contention during system reset or power sequencing without external pull-ups.
Operating Temperature	0°C to 70°C - qualified for commercial-grade industrial control and computing applications, not extended/military range.

Pinout & Package

SN74ALS29825DW is supplied in a 24-pin SOIC (Small-Outline Integrated Circuit) package (DW suffix), 7.5 mm wide, with 0.65 mm lead pitch and gull-wing leads compatible with standard surface-mount reflow profiles.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 23	OC1, OC2, OC3	Multiuser output control inputs - any low input forces all Q outputs into high-impedance; OR logic enables flexible bus arbitration.
3–10	1D–8D	Noninverting data inputs - latch values on rising CLK edge when CLKEN is low; retain state when CLKEN is high.
11	CLR	Asynchronous active-low clear - forces all Q outputs low immediately, overriding clock and enable states.
12	GND	Ground reference - must be connected to system ground plane with low-inductance path to minimize switching noise.
13	VCC	+5 V supply - requires local 0.1 µF ceramic bypass capacitor placed within 5 mm of pin to suppress supply bounce.
14, 15	CLKEN, CLK	Edge-triggered clock enable and clock - CLKEN low enables CLK sampling; CLKEN high freezes output state regardless of CLK activity.
16–23	1Q–8Q	Three-state noninverting outputs - driven high/low when OCx are all high; high-Z otherwise, with undershoot protection.
24	NC	No connect - internally unconnected; must remain floating or tied to GND per layout best practice (no voltage applied).

Key Features

Feature	Design Value
Functionally Equivalent to AMD AM29825	Direct drop-in replacement for AM29825 in existing designs - identical pinout, timing, and electrical behavior confirmed per datasheet cross-reference.
Multiple Output Enables (OC1/OC2/OC3)	Enables hardware-level bus arbitration across up to three independent controllers without software coordination or external logic.
Undershoot Protection Circuitry	Prevents output pins from sinking below −1.2 V during fast bus transitions - eliminates need for external clamping diodes in noisy environments.
Power-Up High-Impedance State	Guarantees zero bus contention at power-on - critical for hot-swap-capable backplanes and modular I/O systems.
Buffered Control Inputs	Reduces DC loading on upstream logic by limiting IIH/IIL to ≤20 µA/−0.2 mA - preserves fanout margin in dense TTL fanout chains.

Applications

Industrial Backplane Bus Interface	Legacy Computer I/O Port Expansion
Use Scenario: Interfacing microcontroller I/O ports to a shared 8-bit parallel backplane with multiple plug-in modules. IC Role / Device Role / Timing Role: Bidirectional bus driver and multiuser register - holds data stable during module selection and isolates inactive modules via OC controls. Use Value: Eliminates need for discrete tristate buffers and address decoders; enables simultaneous register updates across up to three independent bus masters.	Use Scenario: Adding parallel printer or floppy disk controller ports to vintage 8-bit computer systems (e.g., Z80/8080-based). IC Role / Device Role / Timing Role: Synchronized I/O port latch - captures CPU write data on CLK↑ and presents it to peripheral while maintaining bus isolation during read cycles. Use Value: Provides clean 5 V TTL-compatible handshaking with guaranteed setup/hold times (tsu = 2 ns, th = 2 ns) and no external pull-up requirements.
Programmable Logic Controller (PLC) Input Register	Test Equipment Digital Pattern Generator
Use Scenario: Capturing real-time sensor status bits (e.g., limit switches, pressure sensors) in industrial PLC rack-mounted I/O modules. IC Role / Device Role / Timing Role: Asynchronous input register with priority clear - samples field inputs synchronously to system clock while allowing emergency reset via CLR. Use Value: Delivers deterministic sampling window (tPLH/tPHL ≤ 10 ns), undershoot immunity for long cable runs, and fail-safe power-up isolation.	Use Scenario: Generating repeatable 8-bit digital stimulus patterns for IC functional testing in automated test equipment (ATE) fixtures. IC Role / Device Role / Timing Role: Programmable pattern register - stores test vectors under CLKEN control and drives DUT inputs with high-current (48 mA) drive capability. Use Value: Supports fast vector rates (≥50 MHz effective) due to low propagation delay and eliminates need for level-shifting or buffering stages.

Industrial Backplane Bus Interface

Legacy Computer I/O Port Expansion

Use Scenario: Interfacing microcontroller I/O ports to a shared 8-bit parallel backplane with multiple plug-in modules.

IC Role / Device Role / Timing Role: Bidirectional bus driver and multiuser register - holds data stable during module selection and isolates inactive modules via OC controls.

Use Value: Eliminates need for discrete tristate buffers and address decoders; enables simultaneous register updates across up to three independent bus masters.

Use Scenario: Adding parallel printer or floppy disk controller ports to vintage 8-bit computer systems (e.g., Z80/8080-based).

IC Role / Device Role / Timing Role: Synchronized I/O port latch - captures CPU write data on CLK↑ and presents it to peripheral while maintaining bus isolation during read cycles.

Use Value: Provides clean 5 V TTL-compatible handshaking with guaranteed setup/hold times (tsu = 2 ns, th = 2 ns) and no external pull-up requirements.

Programmable Logic Controller (PLC) Input Register

Test Equipment Digital Pattern Generator

Use Scenario: Capturing real-time sensor status bits (e.g., limit switches, pressure sensors) in industrial PLC rack-mounted I/O modules.

IC Role / Device Role / Timing Role: Asynchronous input register with priority clear - samples field inputs synchronously to system clock while allowing emergency reset via CLR.

Use Value: Delivers deterministic sampling window (tPLH/tPHL ≤ 10 ns), undershoot immunity for long cable runs, and fail-safe power-up isolation.

Use Scenario: Generating repeatable 8-bit digital stimulus patterns for IC functional testing in automated test equipment (ATE) fixtures.

IC Role / Device Role / Timing Role: Programmable pattern register - stores test vectors under CLKEN control and drives DUT inputs with high-current (48 mA) drive capability.

Use Value: Supports fast vector rates (≥50 MHz effective) due to low propagation delay and eliminates need for level-shifting or buffering stages.

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit tristate D-flip-flop applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74ALS29826DW	Inverting D inputs (vs. noninverting in SN74ALS29825DW); identical timing, drive, and control logic.	Required where upstream logic provides inverted data or where complementary output polarity is needed for bus termination matching.	Select SN74ALS29826DW only when inverting data path is explicitly required; otherwise, SN74ALS29825DW is preferred for direct D-to-Q mapping.
SN74F29825N	Fast TTL family (not ALS); higher ICC (140 mA), faster tPLH/tPHL (≤7 ns), but no undershoot protection or buffered OC inputs.	Suitable for speed-critical applications where power efficiency and robustness are secondary to raw timing performance.	Choose SN74F29825N only if design requires <7 ns propagation and can tolerate higher power and reduced noise immunity.

Compared with SN74ALS29826DW and SN74F29825N, the SN74ALS29825DW offers optimal balance of noise-immune outputs, low power, and proven reliability in bus-holding applications - making it the preferred choice for industrial and legacy-compatibility designs where robustness and predictable timing outweigh marginal speed gains.

Availability

SN74ALS29825DW is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy computer I/O expansion, programmable logic controller input registers, and test equipment digital pattern generation requiring stable component supply and long-term obsolescence management.

Supply support for SN74ALS29825DW 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 SN74ALS29825DW belongs to TI's legacy Advanced Low-Power Schottky (ALS) logic product line, engineered for high-reliability, bus-oriented digital systems requiring TTL compatibility, robust noise immunity, and deterministic timing in commercial-temperature environments.

FAQ

What is the function of the OC1, OC2, and OC3 pins on the SN74ALS29825DW?

The OC1, OC2, and OC3 pins on the SN74ALS29825DW are multiuser output control inputs implementing OR logic: if any one is low, all eight Q outputs enter high-impedance (Z) state. This allows hardware-level bus arbitration without software intervention. The SN74ALS29825DW uses this feature to isolate inactive devices on shared data buses while preserving internal flip-flop state - critical for multi-master systems.

Does the SN74ALS29825DW have a power-up high-impedance state, and why does it matter?

Yes, the SN74ALS29825DW powers up with all Q outputs in high-impedance state, preventing bus contention during system initialization. This behavior is hardwired and requires no external reset circuitry. For designs using the SN74ALS29825DW in modular backplanes or hot-pluggable I/O cards, this eliminates risk of data corruption or supply rail collapse at power-on - a key reliability feature absent in many contemporary logic devices.

How does the SN74ALS29825DW differ from the SN74ALS29826DW?

The SN74ALS29825DW features noninverting D inputs, while the SN74ALS29826DW has inverting D inputs; all other timing, drive strength, control logic, and pinout are identical. This means the SN74ALS29825DW propagates D-input values directly to Q outputs on clock edges, whereas the SN74ALS29826DW outputs the complement. Both share the same ALS process, 5 V operation, and OC/CLR functionality - making them functionally interchangeable only when data polarity is accounted for in system design.

What is the maximum capacitive load the SN74ALS29825DW can drive reliably?

The SN74ALS29825DW is characterized for CL = 50 pF and CL = 300 pF in its switching specifications, with tPLH/tPHL increasing from ≤10 ns to ≤21 ns as load rises. Its ±24 mA/48 mA drive capability supports direct connection to ≥10 standard TTL loads (each ~10 pF + 1.6 mA). For reliable operation beyond 300 pF, layout optimization (short traces, ground plane) and verification of setup/hold margins using the published tsu = 2 ns and th = 2 ns values are required - the SN74ALS29825DW does not specify derating beyond 300 pF.

Is the SN74ALS29825DW suitable for use in new designs today?

Yes - the SN74ALS29825DW remains viable for new industrial, test, and legacy-replacement designs where 5 V TTL compatibility, proven reliability, and bus-holding capability are required. Texas Instruments continues to manufacture and support this part under its long-term product assurance program. While newer CMOS alternatives exist, the SN74ALS29825DW offers unique advantages including undershoot protection, power-up Z-state, and direct AMD AM29825 equivalence - making it the preferred choice for maintaining or extending existing bus architectures.

SN74ALS29825DW 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:: -

SN74ALS29825DW FAQ

1.How can I place an order for SN74ALS29825DW through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74ALS29825DW 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 SN74ALS29825DW reliable?

The price and inventory of SN74ALS29825DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS29825DW is usually 5 days.

3.What payment methods are accepted for SN74ALS29825DW?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS29825DW transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74ALS29825DW?

SN74ALS29825DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74ALS29825DW 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 SN74ALS29825DW?

For technical support, including SN74ALS29825DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS29825DW requirements.

6.How does Aetrix verify that SN74ALS29825DW is sourced from the original manufacturer or authorized distributors?

All SN74ALS29825DW 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 SN74ALS29825DW meets industry standards.

7.What is the process for return or replacement of SN74ALS29825DW?

All SN74ALS29825DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS29825DW, 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 SN74ALS29825DW part is unused and in its original packaging.

Return procedure for SN74ALS29825DW:

1.Submit a request within 90 days.

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

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