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Texas Instruments SN74AS756DWR
- Part No.:
- SN74AS756DWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74AS756DWR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,565
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Product details
Overview
SN74AS756DWR from Texas Instruments is an octal noninverting buffer/line driver with open-collector outputs, designed for memory address bus driving and clock distribution in TTL-compatible systems. It features dual 4-bit channels, symmetrical active-low output-enable (1OE/2OE), pnp input structure for reduced DC loading, and operates over 0°C to 70°C at VCC = 4.5–5.5 V.
For engineers reviewing the SN74AS756DWR datasheet, SN74AS756DWR pinout, SN74AS756DWR application, or SN74AS756DWR equivalent, this device serves as a high-speed, open-collector alternative to 'AS240A/'AS241 for bus interfacing, address buffering, and level-translated signal routing where wired-OR logic or voltage-level flexibility is required.
Technical Context
The SN74AS756DWR implements two independent 4-bit noninverting buffer sections, each with dedicated active-low output-enable control (1OE and 2OE). Its pnp-input architecture minimizes input current draw, while open-collector outputs support wired-OR configurations and interface directly with 5-V or mixed-voltage buses.
It eliminates 3-state overlap timing constraints by using open-collector outputs instead of tristate drivers - enabling simpler bus arbitration without enable-synchronization logic. Propagation delays are asymmetric: tPHL (A→Y) as low as 1 ns, tPLH up to 19 ns, reflecting optimized low-to-high transition design for pull-up-limited loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - compatible with standard 5-V TTL supply rails and tolerant of nominal ±10% variation. |
| IOL (max) | 64 mA per output - supports direct drive of multiple TTL inputs or termination resistors down to ~78 Ω with 0.55 V VOL. |
| tPHL (A→Y) | 1 ns min - enables sub-nanosecond critical-path timing in address decode or clock fanout applications. |
| tPLH (A→Y) | 19 ns max - defines worst-case rise time under 50-pF load and 500-Ω pull-up, critical for setup margin calculation. |
| VIK (input clamp) | −1.2 V - provides robust negative transient immunity on address/data lines, preventing latch-up during hot-swap or noise events. |
| IIH / IIL | 20 µA high-level / −0.5 mA low-level input current - ensures minimal loading on upstream drivers, preserving fan-out headroom. |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade industrial and computing equipment environments. |
Pinout & Package
SN74AS756DWR uses a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | 1OE | Active-low enable for first 4-bit buffer channel (1Y1–1Y4); disables outputs to high-impedance (open-collector off-state). |
| 2–5, 8–9 | 1A1–1A4, 2A1–2A4 | Noninverting data inputs for two independent 4-bit channels; pnp-input structure reduces DC loading vs. standard TTL. |
| 11–14, 16–18 | 1Y1–1Y4, 2Y1–2Y4 | Open-collector outputs; require external pull-up to define HIGH level - supports mixed-voltage interfacing and wired-OR logic. |
| 19 | 2OE | Active-low enable for second 4-bit buffer channel (2Y1–2Y4); independently controllable for staggered bus access. |
| 10, 20 | GND, VCC | Power terminals; decoupling capacitor placement near Pin 10 (GND) and Pin 20 (VCC) is critical for noise suppression in high-speed switching. |
Key Features
| Feature | Design Value |
|---|---|
| Open-collector outputs | Enable wired-OR bus architectures and flexible voltage-level translation - no internal pull-ups required, reducing power and layout complexity. |
| pnp input structure | Reduces input current to ≤20 µA (IIH) and −0.5 mA (IIL), minimizing loading on preceding logic and improving system-level fan-out. |
| Dual independent OE controls | Allow precise, non-overlapping enable sequencing between two 4-bit channels - eliminates bus contention without external timing logic. |
| Elimination of 3-state overlap protection | Removes need for enable-synchronization circuitry in memory address drivers, simplifying PCB layout and reducing BOM count. |
| High-speed propagation | tPHL as low as 1 ns supports tight timing budgets in CPU address latching and high-frequency clock distribution paths. |
Applications
| Memory Address Buffering | Clock Distribution Network |
|---|---|
|
Use Scenario: Driving 16-bit address bus from microprocessor to multiple memory ICs with shared address decoding logic. IC Role / Device Role / Timing Role: Noninverting octal buffer providing current gain and noise-immune signal regeneration for parallel address lines. Use Value: Open-collector outputs allow common pull-up to memory VCC (e.g., +5 V), while pnp inputs minimize loading on CPU address pins - extending reliable trace length and fan-out. |
Use Scenario: Distributing a master system clock to multiple peripheral controllers requiring synchronized enable timing. IC Role / Device Role / Timing Role: Low-skew buffer replicating clock signal across four downstream loads per channel, with independent OE gating. Use Value: 1 ns tPHL ensures minimal clock skew between buffered outputs, supporting >50 MHz clock domains when paired with appropriate pull-up networks. |
| Bus Interface Translation | Legacy System Expansion |
|
Use Scenario: Interfacing 5-V TTL address/data bus to mixed-voltage peripherals (e.g., +3.3 V I/O devices via level-shifting pull-ups). IC Role / Device Role / Timing Role: Voltage-flexible bus driver using external pull-up to intermediate rail (e.g., 3.3 V), enabling safe bidirectional voltage translation. Use Value: Open-collector outputs tolerate voltages up to 7 V, allowing direct connection to higher-voltage buses without clamping diodes or level shifters. |
Use Scenario: Upgrading vintage industrial controller backplane with modern memory modules while retaining original 5-V TTL signaling. IC Role / Device Role / Timing Role: Drop-in replacement for obsolete 'AS240A/'AS241 in legacy address driver slots, maintaining identical pinout and timing behavior. Use Value: Identical DW-package footprint and electrical specs ensure zero PCB modification - critical for field-replaceable module upgrades in deployed equipment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal open-collector buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS240N | Octal inverting buffer with 3-state (not open-collector) outputs; requires overlap-safe OE timing control. | Suitable for tristate bus systems but incompatible with wired-OR or mixed-voltage pull-up schemes. | Select only if existing design relies on 3-state arbitration and board layout cannot accommodate pull-up resistors. |
| SN74ALS244N | Lower drive (24 mA IOL), slower speed (tPHL = 5 ns min), standard TTL inputs (higher IIH/IIL), same DW/N packages. | Better suited for cost-sensitive, lower-speed legacy systems where fan-out and noise immunity are less critical. | Choose when power budget is constrained and 19 ns tPLH is acceptable - avoids AS-series higher current consumption. |
Compared with SN74AS240N and SN74ALS244N, the SN74AS756DWR uniquely combines open-collector flexibility, sub-ns turn-on speed, and pnp-input efficiency - making it optimal for high-density address buffering where bus contention avoidance and voltage adaptability are mandatory.
Availability
SN74AS756DWR is available at Aetrix Electronics and suitable for memory subsystem design, industrial backplane expansion, and legacy system refurbishment requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74AS756DWR 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 SN74AS756DWR belongs to TI's Advanced Schottky (AS) logic family - engineered for high-speed, low-power address and clock buffering in memory-intensive systems where timing precision and bus reliability are critical.
FAQ
What is the maximum output sink current specification for SN74AS756DWR?
The SN74AS756DWR guarantees a minimum output sink current (IOL) of 64 mA per channel under VCC = 4.5 V and VOL = 0.55 V conditions. This rating allows direct drive of multiple TTL loads or termination into 5-V buses with standard 330-Ω pull-ups, ensuring robust logic LOW assertion even under heavy capacitive loading.
Does SN74AS756DWR support mixed-voltage interfacing?
Yes, SN74AS756DWR supports mixed-voltage interfacing via its open-collector outputs: external pull-up resistors can connect to any voltage rail up to 7 V (absolute max), enabling interoperability between 5-V address buses and 3.3-V peripherals without additional level-shifting ICs - provided input VIH/VIL thresholds are met.
Is SN74AS756DWR pin-compatible with SN74AS240 or SN74AS241?
No, SN74AS756DWR is not pin-compatible with SN74AS240 or SN74AS241. While functionally related as octal buffers, SN74AS756DWR uses dual independent OE controls (1OE/2OE) and open-collector outputs, whereas SN74AS240/241 feature single OE and 3-state outputs - resulting in different pin assignments and incompatible enable logic.
What is the recommended pull-up resistor value for SN74AS756DWR outputs?
A 330-Ω pull-up resistor to 5 V is commonly used with SN74AS756DWR to achieve <10 ns rise time under 50-pF load while maintaining VOL ≤ 0.55 V at 64 mA sink. For 3.3-V systems, 220 Ω is typical; values must be validated against actual bus capacitance and timing requirements per application.
Can SN74AS756DWR replace SN74AS757DWR in a design?
No - SN74AS756DWR and SN74AS757DWR differ in logic function: SN74AS756DWR is noninverting (A→Y), while SN74AS757DWR is inverting (A→Y̅). Swapping them would invert all eight outputs, breaking functional correctness unless compensated by upstream logic inversion or firmware adjustment.
SN74AS756DWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Logic Type:
- Buffer, Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- Input Type:
- -
- Output Type:
- Open Collector
- Current - Output High, Low:
- -, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74AS756DWR FAQ
1.How can I place an order for SN74AS756DWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS756DWR 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 SN74AS756DWR reliable?
The price and inventory of SN74AS756DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS756DWR is usually 5 days.
3.What payment methods are accepted for SN74AS756DWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS756DWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS756DWR?
SN74AS756DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS756DWR 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 SN74AS756DWR?
For technical support, including SN74AS756DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS756DWR requirements.
6.How does Aetrix verify that SN74AS756DWR is sourced from the original manufacturer or authorized distributors?
All SN74AS756DWR 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 SN74AS756DWR meets industry standards.
7.What is the process for return or replacement of SN74AS756DWR?
All SN74AS756DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS756DWR, 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 SN74AS756DWR part is unused and in its original packaging.
Return procedure for SN74AS756DWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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