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Texas Instruments SN74ALS746DW
- Part No.:
- SN74ALS746DW
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74ALS746DW.pdf
- Description:
- BUS DRIVER, ALS SERIES
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Inventory:3,825
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Product details
Overview
SN74ALS746DW from Texas Instruments is an octal inverting buffer/line driver with 3-state outputs, designed for bus driving and memory address register buffering in TTL-compatible systems. It features integrated 20-kΩ input pullup resistors, dual output-enable (OE1/OE2) NOR logic control, and data-flow-through pinout (inputs on one side, outputs on the other) in a 20-pin SOIC (DW) package. It operates from 0°C to 70°C with VCC = 4.5–5.5 V.
For engineers reviewing the SN74ALS746DW datasheet, SN74ALS746DW pinout, SN74ALS746DW application, or SN74ALS746DW equivalent, key selection considerations include its inverted output logic, 3-state enable architecture, input pullup integration, propagation delay (tPLH/tPHL ≤ 12 ns), and compatibility with legacy ALS-level TTL bus systems requiring high-impedance isolation.
Technical Context
The SN74ALS746DW implements dual independent 3-state enable inputs (OE1 and OE2) connected via a 2-input NOR gate - either high disables all eight outputs into high-impedance. Its internal structure integrates 20-kΩ pullup resistors on all eight A-inputs, eliminating external termination components when driving high-impedance buses.
It delivers inverted buffered data (Y = NOT A), supports ±15 mA high-level and +24 mA low-level output drive, and meets ALS family timing with tPZH/tPZL ≤ 20 ns and tPLH/tPHL ≤ 12 ns at CL = 50 pF. The device is strictly TTL-compatible, not CMOS or LVTTL, and requires VCC = 5 V nominal operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures stable operation across standard TTL supply tolerances without regulation. |
| Output Drive | IOH = −15 mA / IOL = +24 mA - sufficient to drive multiple TTL loads or terminate unterminated buses. |
| Propagation Delay | tPLH/tPHL ≤ 12 ns - enables reliable operation in 25+ MHz bus systems with tight timing margins. |
| Enable Timing | tPZH/tPZL ≤ 20 ns - guarantees fast bus release and acquisition during dynamic bus arbitration. |
| Input Pullup | 20 kΩ internal to VCC - eliminates need for external pullups in tri-state bus hold applications. |
| Operating Temp | 0°C to 70°C - certified for commercial-grade embedded and industrial control environments. |
| Logic Function | Inverting buffer (Y = NOT A) with dual-NOR 3-state control - provides polarity-consistent signal conditioning and clean bus isolation. |
Pinout & Package
SN74ALS746DW uses a 20-pin SOIC (DW) package per JEDEC MS-013, 7.6 mm × 13.0 mm body, 1.27 mm pitch, max height 2.65 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8, 9 | A1–A8, OE1, OE2 | Inputs: eight data lines (A1–A8) and two independent output-enable controls (OE1, OE2). |
| 10 | GND | Ground reference for all logic and output stages; required for noise immunity and current return path. |
| 11–18 | Y1–Y8 | Inverted buffered outputs - each Yn = NOT An, individually controllable via OE1/OE2 NOR logic. |
| 19 | VCC | Positive supply (4.5–5.5 V); powers internal logic, pullups, and output drivers. |
| 20 | NC | No connect - unused pin; must remain unconnected per TI design specification. |
Key Features
| Feature | Design Value |
|---|---|
| Data-flow-through pinout | Inputs (A1–A8, OE1, OE2) on left side, outputs (Y1–Y8) on right side - simplifies PCB routing and minimizes trace crosstalk in dense bus layouts. |
| Integrated 20-kΩ input pullups | Eliminates external pullup resistors on all eight inputs - reduces BOM count and board space in bus-hold configurations. |
| Dual 3-state enable (NOR logic) | Either OE1 or OE2 high forces all outputs into high-Z - enables flexible bus arbitration using separate control domains. |
| Inverting output logic | Yn = NOT An - preserves signal inversion integrity in cascaded TTL logic chains requiring phase consistency. |
| ALS-family performance | Matches SN74ALS240A speed/power but with optimized pinout - allows drop-in replacement where layout permits. |
Applications
| Memory Address Buffering | Parallel Bus Isolation |
|---|---|
|
Use Scenario: Driving 8-bit address lines from a microprocessor to multiple memory ICs on a shared bus. IC Role / Device Role / Timing Role: Inverting buffer with 3-state control isolates address bus during DMA or peripheral access cycles. Use Value: Integrated pullups maintain valid high state on address lines when CPU is in reset or high-Z mode, preventing undefined memory access. |
Use Scenario: Interfacing multiple peripheral controllers to a common data bus with dynamic arbitration. IC Role / Device Role / Timing Role: Bidirectional bus driver enabling/disabling data flow using OE1/OE2 signals synchronized to bus grant. Use Value: Sub-20 ns enable/disable times ensure minimal bus turnaround latency, supporting >20 MHz bus clock rates. |
| Legacy System Bus Termination | TTL-Level Signal Level Translation |
|
Use Scenario: Replacing discrete pullup networks on vintage computer backplanes or industrial PLC I/O modules. IC Role / Device Role / Timing Role: Passive bus keeper replacing 8× external 20-kΩ resistors while preserving signal integrity. Use Value: Reduces component count by eight resistors per device and eliminates associated solder joints and layout area. |
Use Scenario: Converting between different TTL subfamilies (e.g., LS-to-ALS) where voltage thresholds and drive strength differ. IC Role / Device Role / Timing Role: Level-shifting buffer ensuring VIH/VIL compatibility and fanout compliance across mixed-logic systems. Use Value: Guaranteed 2.4 V VOH at −15 mA and 0.5 V VOL at +24 mA meet ALS input thresholds while driving up to 20 LS loads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS240AN | Same ALS family, non-inverting outputs, identical pinout except A/Y polarity; no internal pullups. | Requires external pullups for bus-hold; suitable where signal inversion is undesirable. | Select SN74ALS240AN only if system logic requires non-inverted buffering and external termination is acceptable. |
| SN74F240N | Fast TTL variant: faster tPLH/tPHL (≤ 8 ns) but higher ICC (18–25 mA), no internal pullups, same 20-pin DIP footprint. | Better speed at cost of power and thermal load; incompatible pin-for-pin due to different enable logic (active-low only). | Choose SN74F240N only when sub-10 ns propagation is mandatory and board-level pullups are already present. |
Compared with SN74ALS240AN and SN74F240N, the SN74ALS746DW uniquely combines inversion, integrated pullups, and dual-NOR enable in a single SOIC package - making it the only option for space-constrained legacy bus designs requiring self-terminating inverted drive without layout redesign.
Availability
SN74ALS746DW is available at Aetrix Electronics and suitable for memory subsystem buffering, parallel bus isolation, and legacy TTL system refurbishment requiring stable component supply and long-term obsolescence support.
Supply support for SN74ALS746DW 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 innovator founded in 1930, specializing in analog, embedded processing, and logic technologies for industrial, automotive, and communications markets.
The SN74ALS746DW belongs to TI's 74ALS advanced low-power Schottky logic family, engineered for high-speed, low-power TTL-compatible digital interfacing in commercial-temperature computing and control systems.
FAQ
What logic function does the SN74ALS746DW implement?
The SN74ALS746DW implements an octal inverting buffer with 3-state outputs. Each output Yn equals the logical inverse of its corresponding input An (Yn = NOT An). Output enable is controlled by a dual-input NOR gate: if either OE1 or OE2 is high, all eight outputs enter high-impedance state. This behavior is explicitly defined in the logic diagram and truth table of the SDAS052A datasheet.
Does the SN74ALS746DW have internal pullup resistors, and what value are they?
Yes, the SN74ALS746DW includes internal 20-kΩ pullup resistors connected between each of the eight A-inputs and VCC. This is confirmed in the "description" section and logic diagram footnote of the SDAS052A datasheet, which states "All input pullup resistors are 20 kΩ." These eliminate the need for external pullups in bus-hold applications.
What is the operating temperature range for the SN74ALS746DW?
The SN74ALS746DW is characterized for operation from 0°C to 70°C, as specified in both the "absolute maximum ratings" and "recommended operating conditions" tables of the SDAS052A datasheet. This defines its commercial-grade temperature rating and excludes extended or industrial temperature variants.
Is the SN74ALS746DW pin-compatible with the SN74ALS240A?
No, the SN74ALS746DW is not pin-compatible with the SN74ALS240A. While both are octal buffers in 20-pin packages, the SN74ALS746DW has a data-flow-through pinout (inputs on left, outputs on right), whereas the SN74ALS240A uses a different arrangement. The SN74ALS746DW datasheet explicitly positions it as a functional alternative-not a pin-for-pin replacement-with distinct pin assignments for A/Y signals.
What package type is used for the SN74ALS746DW, and what are its key dimensions?
The SN74ALS746DW uses a 20-pin SOIC (DW) package per JEDEC MS-013. Key dimensions are 7.6 mm × 13.0 mm body size, 1.27 mm lead pitch, and maximum height of 2.65 mm. These mechanical specifications are documented in TI's DW0020A package outline drawing referenced in the SDAS052A datasheet addendum.
SN74ALS746DW 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:
- -
SN74ALS746DW FAQ
1.How can I place an order for SN74ALS746DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS746DW 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 SN74ALS746DW reliable?
The price and inventory of SN74ALS746DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS746DW is usually 5 days.
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SN74ALS746DW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS746DW 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 SN74ALS746DW?
For technical support, including SN74ALS746DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS746DW requirements.
6.How does Aetrix verify that SN74ALS746DW is sourced from the original manufacturer or authorized distributors?
All SN74ALS746DW 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 SN74ALS746DW meets industry standards.
7.What is the process for return or replacement of SN74ALS746DW?
All SN74ALS746DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS746DW, 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 SN74ALS746DW part is unused and in its original packaging.
Return procedure for SN74ALS746DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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