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Texas Instruments SN74AS253AD
- Part No.:
- SN74AS253AD
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74AS253AD.pdf
- Description:
- IC MULTIPLEXER 2 X 4:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,729
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Product details
Overview
SN74AS253AD from Texas Instruments is a dual 4-line to 1-line data selector/multiplexer with independent 3-state outputs, designed for bus-oriented digital systems. It features two independent 4-input sections (1C0–1C3 and 2C0–2C3), common select lines (A/B), separate output-enable inputs (1OE/2OE), and operates at 0°C to 70°C with 5 V supply. It enables parallel-to-serial conversion and multiplexing in TTL-compatible logic circuits.
For engineers reviewing the SN74AS253AD datasheet, SN74AS253AD pinout, SN74AS253AD application, or SN74AS253AD equivalent, key selection criteria include its 13.5 ns max propagation delay (A/B to Y), 48 mA low-level output drive, 15 mA high-level sink capability, 3-state bus interface support, and SOIC-16 package compatibility with industrial control and legacy TTL system upgrades.
Technical Context
The SN74AS253AD implements two independent 4:1 multiplexer sections sharing select inputs A and B, each with dedicated output-enable (1OE, 2OE) controlling high-impedance state. Its internal architecture uses binary-decoded AND-OR logic with inverters and drivers to route selected data inputs to outputs Y1 and Y2.
Each section supports full TTL input thresholds (VIL = 0.8 V, VIH = 2 V), delivers VOH ≥ 2.4 V at −15 mA, and VOL ≤ 0.5 V at 48 mA. Propagation delays are asymmetric: data-to-output (tPLH/tPHL) as low as 2.5 ns, select-to-output as low as 3 ns, and enable-to-output transitions down to 1 ns (tPHZ).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Function | Dual 4:1 data selector/multiplexer with independent 3-state outputs |
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard TTL and 5 V logic rails |
| Propagation Delay | Max 13.5 ns (A/B → Y) - enables high-speed address/data routing in 20+ MHz systems |
| Output Drive | IOL = 48 mA / IOH = −15 mA - directly drives heavy capacitive loads or multiple TTL inputs |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded and industrial control applications |
| Package | SOIC-16 (D package) - surface-mount compatible with automated PCB assembly |
| Input Thresholds | VIL = 0.8 V, VIH = 2 V - ensures robust noise margin against TTL-level signals |
Pinout & Package
SN74AS253AD is housed in a 16-pin plastic small-outline integrated circuit (SOIC) package (D package), 7.5 mm wide, with 1.27 mm pitch and gull-wing leads. Pin 1 is located at the top-left corner with polarity indicator (notch or dot).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | 1C0 | Data input 0 for first multiplexer section |
| 2 | 1C1 | Data input 1 for first multiplexer section |
| 3 | 1C2 | Data input 2 for first multiplexer section |
| 4 | 1C3 | Data input 3 for first multiplexer section |
| 5 | 1Y | Output for first multiplexer section (3-state) |
| 6 | 2C0 | Data input 0 for second multiplexer section |
| 7 | 2C1 | Data input 1 for second multiplexer section |
| 8 | GND | Ground reference for power and signal integrity |
| 9 | 2Y | Output for second multiplexer section (3-state) |
| 10 | 2C2 | Data input 2 for second multiplexer section |
| 11 | 2C3 | Data input 3 for second multiplexer section |
| 12 | 2OE | Active-low output-enable for second section |
| 13 | 1OE | Active-low output-enable for first section |
| 14 | A | Common select line A (LSB of 2-bit address) |
| 15 | B | Common select line B (MSB of 2-bit address) |
| 16 | VCC | +5 V supply rail - powers both sections and internal logic |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent 4:1 multiplexers | Enables simultaneous routing of two separate 4-input data streams using shared A/B selects |
| Individual 3-state output control | 1OE and 2OE allow selective bus arbitration without external gating or timing coordination |
| High-current TTL-compatible outputs | 48 mA sink and 15 mA source capability eliminates need for buffer stages in bus-driving roles |
| Low propagation delay | As fast as 2.5 ns (data-to-Y) and 3 ns (select-to-Y) supports >70 MHz clock-domain interfacing |
| Standard SOIC-16 footprint | Direct drop-in replacement for legacy 74LS/ALS253 variants in space-constrained PCB layouts |
Applications
| Industrial PLC I/O Expansion | Legacy System Bus Multiplexing |
|---|---|
|
Use Scenario: Expanding discrete input monitoring across multiple sensor banks in programmable logic controllers. IC Role / Device Role / Timing Role: SN74AS253AD acts as a scan-select hub, sequentially routing 8 sensor inputs (via two 4:1 sections) onto a shared status bus under microcontroller control. Use Value: Reduces GPIO count by 75% while maintaining real-time visibility into all inputs via time-multiplexed reads - enabled by sub-14 ns propagation and deterministic 3-state disable timing. |
Use Scenario: Consolidating address/data paths between older 8-bit microprocessors and peripheral memory or I/O chips. IC Role / Device Role / Timing Role: SN74AS253AD serves as a bidirectional bus switch controller, selecting between alternate memory banks or peripheral registers using A/B address bits and OE gating. Use Value: Eliminates discrete gate logic and reduces board area by integrating dual 4:1 selection + 3-state drive in one SOIC-16 device - critical for retrofitting compact backplane designs. |
| Test Equipment Signal Routing | Digital Logic Training Platform |
|
Use Scenario: Configurable signal path selection in automated test fixtures verifying multi-channel digital subsystems. IC Role / Device Role / Timing Role: SN74AS253AD functions as a reprogrammable interconnect matrix, directing stimulus signals from pattern generators to DUT pins based on test sequence commands. Use Value: Enables <10 ns channel switching repeatability and 48 mA drive into 50 Ω terminated lines - ensuring signal fidelity during high-speed functional validation. |
Use Scenario: Hands-on demonstration of combinational logic, bus contention avoidance, and multiplexing principles in university electronics labs. IC Role / Device Role / Timing Role: SN74AS253AD provides a physical implementation of Boolean function selection, where students manually toggle A/B/OE to observe truth table behavior and 3-state isolation. Use Value: Robust TTL voltage margins (0.8 V/2 V) and visible LED-driven outputs make logic states unambiguous for pedagogical use - no oscilloscope required for basic verification. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual 4:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS253DR | Slower propagation (21 ns max A/B→Y), lower drive (24 mA IOL), ALS family speed-power trade-off | Suitable for lower-frequency (<10 MHz), low-power legacy systems where heat dissipation is constrained | Choose when cost sensitivity outweighs speed requirements and existing ALS design infrastructure exists |
| SN74HC153N | CMOS technology, wider VCC range (2–6 V), higher input impedance, but only 5.2 mA IOL at 5 V | Preferred for mixed-voltage systems or battery-powered logic, not for driving heavy TTL loads or buses | Choose for new low-power designs requiring 3.3 V compatibility or reduced static current - not for direct SN74AS253AD replacement |
Compared with SN74ALS253DR and SN74HC153N, the SN74AS253AD delivers superior speed and bus-drive strength at the cost of higher ICC (29 mA typical vs. 12 mA for ALS, 4 µA for HC), making it optimal for performance-critical, 5 V-only, TTL-interfaced applications where signal integrity and timing margin are paramount.
Availability
SN74AS253AD is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy system bus multiplexing, test equipment signal routing, and digital logic training platforms requiring stable component supply and long-term obsolescence management.
Supply support for SN74AS253AD 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 SN74AS253AD belongs to TI's advanced Schottky (AS) TTL logic family, engineered for high-speed, high-drive digital interfacing in mission-critical commercial systems where reliability and timing predictability are essential.
FAQ
What is the maximum operating frequency supported by the SN74AS253AD?
The SN74AS253AD does not specify a maximum clock frequency directly, but its fastest propagation delay (tPLH/tPHL from data inputs to Y) is 7.5 ns (max), supporting reliable operation in systems with signal periods exceeding 15 ns - equivalent to a practical upper limit near 65 MHz for clean edge-triggered routing. Timing margins must account for setup/hold requirements of downstream devices when used in synchronous designs.
Can the SN74AS253AD operate with a 3.3 V supply?
No, the SN74AS253AD is specified only for 4.5 V to 5.5 V operation per its recommended conditions. Applying 3.3 V violates the minimum VCC requirement and will result in undefined logic levels, excessive propagation delay, and potential output contention. For 3.3 V systems, consider CMOS alternatives like SN74LVC153 or level-shifting interfaces.
How does the 3-state output control work on the SN74AS253AD?
The SN74AS253AD provides two independent active-low output-enable inputs: 1OE controls the 1Y output, and 2OE controls the 2Y output. When an OE pin is high, its corresponding Y output enters high-impedance (Hi-Z) state regardless of select or data inputs. When OE is low, the selected Cx input appears at Y with full drive strength - enabling precise bus arbitration without external logic.
Is the SN74AS253AD pin-compatible with the SN74LS253N?
Yes, the SN74AS253AD shares identical pinout and function mapping with SN74LS253N and SN74ALS253N in the 16-pin PDIP (N) and SOIC (D) packages. All three devices use the same terminal assignments for A, B, C0–C3, Y, OE, VCC, and GND - allowing direct PCB-level substitution when upgrading speed and drive capability in existing layouts.
What is the purpose of the NC pins in the SN74AS253AD package?
The SN74AS253AD SOIC-16 package has no NC (no-connect) pins - all 16 pins are assigned functional roles as defined in the datasheet. Earlier ceramic packages (e.g., FK, J) list NC pins (e.g., pins 3 and 8 in FK), but the D-package version fully utilizes all terminals. Always verify pin mapping against the SOIC-specific diagram, not generic package drawings.
SN74AS253AD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Multiplexer
- Circuit:
- 2 x 4:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 2.6mA, 24mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74AS253AD FAQ
1.How can I place an order for SN74AS253AD through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS253AD 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 SN74AS253AD reliable?
The price and inventory of SN74AS253AD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS253AD is usually 5 days.
3.What payment methods are accepted for SN74AS253AD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS253AD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS253AD?
SN74AS253AD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS253AD 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 SN74AS253AD?
For technical support, including SN74AS253AD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS253AD requirements.
6.How does Aetrix verify that SN74AS253AD is sourced from the original manufacturer or authorized distributors?
All SN74AS253AD 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 SN74AS253AD meets industry standards.
7.What is the process for return or replacement of SN74AS253AD?
All SN74AS253AD units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS253AD, 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 SN74AS253AD part is unused and in its original packaging.
Return procedure for SN74AS253AD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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