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Texas Instruments SN74AS258NSR
- Part No.:
- SN74AS258NSR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AS258NSR.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:10,000
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Product details
Overview
SN74AS258NSR from Texas Instruments is a 4-bit dual 2-line-to-1-line data selector/multiplexer with 3-state outputs, designed for bus-organized systems. It features 16-pin SOP (NS) package, operates from 0°C to 70°C, supports 4.5–5.5 V supply, delivers ±48 mA output drive, and enables high-speed bus interface with propagation delays as low as 1 ns (tPHL, A/B → Y).
For engineers reviewing the SN74AS258NSR datasheet, SN74AS258NSR pinout, SN74AS258NSR application, or SN74AS258NSR equivalent, this page provides verified functional identity, confirmed timing specs (tPLH/tPHL ≤ 5 ns), true 3-state bus isolation behavior, and validated alternative options for legacy TTL bus interface upgrades.
Technical Context
The SN74AS258NSR implements two independent 2:1 multiplexers per device, each selecting between A or B inputs based on the A/B control line. Its 3-state outputs are disabled when OE is high, enabling direct connection to shared data buses without loading.
It belongs to the 74AS logic family-advanced Schottky TTL-with higher speed and lower power than standard 74LS/ALS variants. Key design traits include 50 pF load-driven switching (CL = 50 pF), 500 Ω source/load termination compatibility, and guaranteed operation across full recommended VCC (4.5–5.5 V) and temperature (0°C to 70°C) ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | 74AS (Advanced Schottky TTL) - ensures compatibility with legacy TTL bus systems while delivering faster switching than 74ALS. |
| Supply Voltage (VCC) | 4.5 V to 5.5 V - supports standard +5 V rail with ±10% tolerance; absolute max 7 V prevents damage during transient overvoltage. |
| Output Drive (IOL/IOH) | 48 mA sink / −15 mA source - sufficient to drive multiple TTL loads or terminate stubs in backplane bus architectures. |
| Propagation Delay (A/B → Y) | 1 ns (min) to 5 ns (max) - enables sub-200 MHz bus clocking in synchronous multiplexed data paths. |
| 3-State Enable Time (tPZH/tPHZ) | 2 ns (min) to 8 ns (max) - allows rapid bus arbitration and dynamic source switching without contention windows. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade industrial control, test equipment, and legacy computing systems. |
| Package | SOP-16 (NS) - surface-mount, 16-pin small-outline package with 1.27 mm pitch; RoHS-compliant NIPDAU finish. |
Pinout & Package
SOP-16 (NS) package: 16-pin surface-mount small-outline package, 10.4 mm × 5.3 mm body, 1.27 mm lead pitch, 2.00 mm max height, RoHS-compliant NIPDAU lead finish, MSL Level-1 (unlimited floor life at <30°C/60% RH).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (A/B) | Multiplexer select control | Chooses active input pair: logic low selects A inputs (1A–4A), high selects B inputs (1B–4B). |
| 2–5, 6–9 (1A–4A, 1B–4B) | Data inputs | Four parallel 2:1 input pairs; each pair feeds one output Y; no internal cross-coupling between channels. |
| 10–13 (1Y–4Y) | 3-state outputs | Active-low enabled; high-Z when OE = high; drives bus only when selected and enabled. |
| 14 (OE) | Output enable | Active-low global enable; overrides A/B selection - all Y outputs go high-impedance when OE = high. |
| 15 (GND) | Ground reference | Primary signal return path; must be low-inductance connection to minimize ground bounce in fast-switching operation. |
| 16 (VCC) | Power supply | +5 V supply; requires local 0.1 µF ceramic decoupling adjacent to pin to suppress high-frequency noise. |
Key Features
| Feature | Design Value |
|---|---|
| High-speed 3-state bus interface | Enables direct connection to shared data buses with <5 ns propagation delay and <10 ns enable/disable times - eliminates need for external bus buffers. |
| Dual independent 2:1 multiplexers | Provides four parallel 2:1 data paths (1A/1B→1Y, ..., 4A/4B→4Y) - supports simultaneous routing of nibble-wide signals without inter-channel delay skew. |
| Robust TTL-compatible I/O | VIH = 2 V min, VIL = 0.8 V max, VOH ≥ 2.4 V @ −15 mA, VOL ≤ 0.5 V @ 48 mA - ensures reliable interfacing with legacy 74-series, microcontrollers, and FPGAs. |
| Low-power advanced Schottky architecture | ICC = 15.5 mA (max, outputs disabled) at VCC = 5.5 V - reduces thermal load vs. standard 74AS257 (19.7 mA), critical in dense PCB layouts. |
| Standardized SOP-16 footprint | NS package matches JEDEC MS-012AC; compatible with automated SMT placement and reflow profiles (MSL-1, 260°C peak). |
Applications
| Industrial PLC Backplane Interface | Legacy Microprocessor Data Bus Expansion |
|---|---|
|
Use Scenario: Routing sensor data from multiple analog input modules to a central ADC controller via shared 4-bit data bus. IC Role / Device Role / Timing Role: Dual 2:1 multiplexer selects between redundant sensor sources per channel; 3-state outputs prevent bus contention during module hot-swap. Use Value: Enables deterministic 4-bit data routing with <5 ns delay and zero bus loading when deselected - improves real-time response in closed-loop control. |
Use Scenario: Expanding Z80 or 8085 CPU address/data bus to support additional peripheral ICs without adding bus transceivers. IC Role / Device Role / Timing Role: Acts as bidirectional data path selector between memory-mapped I/O devices and CPU data lines using OE-controlled 3-state isolation. Use Value: Delivers TTL-compatible drive strength (48 mA sink) and sub-10 ns enable timing - eliminates timing margin loss in 4–6 MHz CPU systems. |
| Test Equipment Signal Routing Matrix | Avionics Maintenance Diagnostic Interface |
|
Use Scenario: Configurable signal path selection in automated test fixtures connecting DUT pins to measurement instruments (DMM, scope, pattern generator). IC Role / Device Role / Timing Role: Provides four independent 2:1 switch paths controlled by FPGA GPIO; 3-state outputs allow cascading multiple SN74AS258NSR units on same bus. Use Value: Guarantees <5 ns channel-to-channel skew and 2.4 V VOH under 15 mA load - ensures signal integrity across multi-board test harnesses. |
Use Scenario: Interfacing legacy ARINC 429 receiver modules with modern diagnostic laptops via RS-232/TTL level-shifted bus. IC Role / Device Role / Timing Role: Multiplexes discrete status bits (e.g., fault flags, sync pulses) from multiple LRUs onto a shared maintenance bus under microcontroller control. Use Value: Supports 0°C to 70°C operation and 5.5 V absolute max rating - withstands avionics bay thermal cycling and power rail transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 4-bit dual 2:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS257NSR | Identical pinout and function but lacks A/B select inversion; outputs mirror SN74AS258NSR when A/B = low, but invert selection logic when A/B = high. | Requires inverted A/B control signal to match SN74AS258NSR behavior; not drop-in replaceable without logic redesign. | Select SN74AS257NSR only if existing firmware/hardware already generates complementary A/B control. |
| SN74ALS258AN | Same function and pinout, but ALS family: slower (max tPHL = 7 ns vs. 4 ns), lower drive (24 mA vs. 48 mA), higher ICC (13 mA vs. 15.5 mA disabled). | Suitable for lower-speed (<10 MHz) or low-power systems where 74AS speed is unnecessary; PDIP package limits high-density SMT designs. | Choose SN74ALS258AN for cost-sensitive, non-speed-critical replacements where through-hole assembly is acceptable. |
Compared with SN74AS257NSR and SN74ALS258AN, the SN74AS258NSR uniquely combines SOP-16 surface-mount compatibility, 48 mA output drive, and sub-5 ns propagation delay - making it optimal for space-constrained, high-throughput legacy bus interfaces requiring precise timing control.
Availability
SN74AS258NSR is available at Aetrix Electronics and suitable for industrial control systems, test equipment signal routing, avionics diagnostics, and legacy microprocessor bus expansion requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74AS258NSR 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 with deep heritage in TTL and interface ICs.
The SN74AS258NSR belongs to TI's 74AS logic family, engineered for high-speed, low-noise digital interface applications in industrial, test, and aerospace systems where legacy TTL compatibility and deterministic timing are critical.
FAQ
What is the maximum operating frequency supported by SN74AS258NSR in a bus interface application?
The SN74AS258NSR does not specify a maximum clock frequency directly, but its worst-case propagation delay (tPHL/tPLH ≤ 5 ns) and enable/disable times (≤ 10 ns) support reliable operation in bus systems clocked up to ~100 MHz. Real-world usable frequency depends on board layout, load capacitance, and termination - for 50 pF CL and 500 Ω R1/R2, timing margins remain intact below 80 MHz in typical industrial backplane designs using SN74AS258NSR.
Can SN74AS258NSR be used as a direct replacement for SN74ALS258AN in an existing PDIP-based design?
No - SN74AS258NSR uses a 16-pin SOP (NS) package, while SN74ALS258AN uses a 16-pin PDIP (N) package; they are not physically interchangeable. However, SN74AS258NSR offers identical pinout numbering and logic function. A PCB redesign is required to accommodate the smaller SOP footprint, but signal routing and netlist remain unchanged. Thermal and electrical performance improves with the NS package's lower inductance and better thermal dissipation.
Does SN74AS258NSR support mixed-voltage operation, such as interfacing with 3.3 V logic?
No - SN74AS258NSR is a 5 V-only TTL device. Its input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) and output levels (VOH ≥ 2.4 V, VOL ≤ 0.5 V) are specified only for VCC = 4.5–5.5 V. Driving it from 3.3 V logic may cause marginal VIH compliance; driving 3.3 V receivers with its 5 V outputs risks overvoltage damage unless level-shifting circuitry is added. Use only in 5 V systems or with proper translation.
How does the 3-state output behavior of SN74AS258NSR prevent bus contention?
When OE is high, all four Y outputs enter high-impedance (Hi-Z) state regardless of A/B or input states - effectively disconnecting the device from the bus. This allows multiple SN74AS258NSR units (or other 3-state devices) to share the same bus lines without electrical conflict. Contention is avoided because only one device has OE low at any time, ensuring exactly one driver is active - a fundamental requirement for safe wired-OR or shared-data-bus architectures.
Is SN74AS258NSR suitable for use in automotive applications?
No - SN74AS258NSR is characterized for 0°C to 70°C operation and is not AEC-Q100 qualified. It lacks automotive-grade screening, extended temperature range (−40°C to 125°C), or enhanced reliability testing required for under-hood or safety-critical vehicle systems. For automotive use, consider TI's automotive-qualified alternatives like SN74LV258A or SN74LVC258A, which offer similar functionality with appropriate qualification and voltage flexibility.
SN74AS258NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 16-SOIC (0.209", 5.30mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- 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-SO
SN74AS258NSR FAQ
1.How can I place an order for SN74AS258NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS258NSR 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 SN74AS258NSR reliable?
The price and inventory of SN74AS258NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS258NSR is usually 5 days.
3.What payment methods are accepted for SN74AS258NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS258NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS258NSR?
SN74AS258NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS258NSR 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 SN74AS258NSR?
For technical support, including SN74AS258NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS258NSR requirements.
6.How does Aetrix verify that SN74AS258NSR is sourced from the original manufacturer or authorized distributors?
All SN74AS258NSR 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 SN74AS258NSR meets industry standards.
7.What is the process for return or replacement of SN74AS258NSR?
All SN74AS258NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS258NSR, 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 SN74AS258NSR part is unused and in its original packaging.
Return procedure for SN74AS258NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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