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Texas Instruments SN74LS126ANSR
- Part No.:
- SN74LS126ANSR
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74LS126ANSR.pdf
- Description:
- IC BUF NON-INVERT 5.25V 14SOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,988
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Product details
Overview
SN74LS126ANSR from Texas Instruments is a quad bus buffer with 3-state outputs, designed for bidirectional data bus isolation and load driving in TTL-compatible digital systems. It features independent active-low output enables per channel, 24 mA low-level output drive, 2.6 mA high-level output current, and operates at 4.75–5.25 V. It is used in legacy industrial control backplanes and memory address/data bus interfaces where controlled bus contention avoidance is required.
For engineers reviewing the SN74LS126ANSR datasheet, SN74LS126ANSR pinout, SN74LS126ANSR application, or SN74LS126ANSR equivalent, this page delivers verified electrical specs, SOP-14 package details, real-world use cases in bus arbitration and level translation, and validated alternative options for design continuity.
Technical Context
The SN74LS126ANSR implements four independent non-inverting buffers, each with an active-low 3-state enable (G) controlling output impedance. When enabled (G = LOW), it drives TTL-compatible logic levels with VOH ≥ 2.4 V at –2.6 mA and VOL ≤ 0.4 V at 24 mA. When disabled (G = HIGH), both output transistors turn off, presenting >10⁹ Ω off-state impedance to the bus.
Its LS-TTL architecture uses Schottky-clamped bipolar transistors to achieve propagation delays of tPLH/tPHL ≤ 15 ns (VCC = 5 V, CL = 45 pF, RL = 667 Ω) and enable/disable times tPZH/tPZL ≤ 25 ns. Input thresholds are VIH = 2 V min and VIL = 0.8 V max, ensuring compatibility with standard TTL and LS families.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.75–5.25 V - ensures stable operation within standard TTL power rail tolerances without regulation overhead. |
| Output Drive (IOL) | 24 mA - sufficient to drive 10+ standard TTL loads directly, eliminating need for external pull-ups on shared buses. |
| Output Drive (IOH) | –2.6 mA - maintains valid VOH ≥ 2.4 V under load, supporting reliable high-level signaling across loaded traces. |
| Propagation Delay | ≤15 ns - enables reliable operation in 33 MHz bus systems with margin for trace skew and setup/hold timing. |
| Enable Polarity | Active-low (G = LOW enables) - matches common bus controller assertion logic for synchronous bus gating. |
| Input Thresholds | VIH = 2 V min, VIL = 0.8 V max - guarantees interoperability with 74LS, 74S, and legacy 74-series logic families. |
| Off-State Leakage | ±20 µA - minimizes bus loading during disable, critical for maintaining signal integrity in multi-driver configurations. |
Pinout & Package
SOP-14 (NS) package: 14-pin small-outline plastic package, 1.27 mm pitch, 8.75 × 4.0 mm body size, 1.75 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1G, 2G, 3G, 4G | Active-low output enable inputs | Each controls one buffer independently; LOW enables output, HIGH forces high-impedance state. |
| 1A–4A | Data inputs | Non-inverting input for corresponding buffer channel; accepts TTL/LS-compatible logic levels. |
| 1Y–4Y | 3-state buffered outputs | Drive bus lines when enabled; present >1 GΩ impedance when disabled to prevent contention. |
| VCC (Pin 14) | Positive supply | 5 V nominal; powers all four channels and internal logic; requires local 0.1 µF bypassing. |
| GND (Pin 7) | Ground reference | Common return for all I/O and internal circuitry; must be low-inductance connection to minimize noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Independent per-channel 3-state control | Enables selective bus segment isolation without affecting other channels-critical for dynamic bus partitioning in multiprocessor systems. |
| 24 mA sink capability | Drives heavy capacitive loads (e.g., 100+ pF bus stubs) without external components, reducing BOM count and layout complexity. |
| Low ICC (12 mA typical) | Reduces system power budget in always-on bus interface circuits compared to standard 74126 (36 mA typical), extending thermal headroom. |
| LS-TTL compatible thresholds | Guarantees robust noise immunity (≥0.4 V DC noise margin) and seamless integration with existing 74LS-based designs. |
| SOP-14 surface-mount packaging | Supports automated assembly and compact PCB layouts while maintaining pin compatibility with PDIP-14 and SOIC-14 variants. |
Applications
| Industrial Backplane Bus Isolation | Legacy Memory Address Buffering |
|---|---|
Use Scenario: Isolating CPU address/data lines from peripheral expansion slots in programmable logic controllers (PLCs) to prevent bus contention during hot-swap events. IC Role / Device Role / Timing Role: Quad 3-state buffer providing channel-selectable bidirectional bus gating with sub-15 ns propagation delay. Use Value: Enables safe insertion/removal of I/O modules without system reset by electrically disconnecting unpowered slots via independent G inputs. | Use Scenario: Driving 16-bit address bus in vintage microcomputer systems (e.g., Z80 or 8085-based) where multiple memory chips share a common bus. IC Role / Device Role / Timing Role: Non-inverting buffer with 24 mA sink strength ensuring clean address transitions across long PCB traces and multiple device inputs. Use Value: Eliminates need for discrete pull-up resistors on address lines, reducing board space and improving rise time consistency across all 16 bits. |
| Test Equipment Signal Routing | RS-232 Level Translation Interface |
Use Scenario: Multiplexing test signals between DUT (device under test) and measurement instruments in automated test fixtures. IC Role / Device Role / Timing Role: Bidirectional bus switch controlled by FPGA GPIOs, enabling dynamic reconfiguration of signal paths without hardware changes. Use Value: Provides deterministic 3-state isolation between instruments, preventing ground loops and signal corruption during path switching. | Use Scenario: Interfacing TTL-level microcontroller UART outputs to RS-232 transceivers requiring inverted logic polarity and higher drive strength. IC Role / Device Role / Timing Role: Logic-level shifter and driver stage converting 0–5 V logic to RS-232-compatible voltage swing requirements. Use Value: Delivers sufficient current to charge RS-232 line capacitance rapidly, ensuring compliant edge rates and minimizing bit errors at 115.2 kbps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffering applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS126AN | Same logic function and electrical specs, but in 14-pin PDIP (N) package instead of SOP-14 (NS). | Requires through-hole assembly and larger PCB footprint; suitable for prototyping or legacy repair, not high-density SMT production. | Select when hand-soldering or socket-based testing is needed; not recommended for new SMT designs. |
| SN74LS126ADR | Identical functionality and specs, packaged in SOIC-14 (D) with 3.9 mm width vs. NS's 4.0 mm; same 1.27 mm pitch and RoHS/NiPdAu finish. | SOIC-D has slightly smaller body width and different tape-and-reel packaging (2500 vs. 2000 units/reel); pinout and thermal performance (θJA = 86°C/W) match NS. | Preferred drop-in replacement for SN74LS126ANSR in new designs where SOIC-D is already standardized in the BOM. |
Compared with SN74LS126AN and SN74LS126ADR, the SN74LS126ANSR offers identical electrical behavior in a SOP-14 package optimized for compact SMT layouts and automated placement-making it ideal for space-constrained industrial control modules where board area and assembly efficiency are prioritized.
Availability
SN74LS126ANSR is available at Aetrix Electronics and suitable for industrial backplane bus isolation, legacy memory address buffering, test equipment signal routing, and RS-232 level translation interfaces requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74LS126ANSR 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 specializing in analog, embedded processing, and logic solutions, with over 90 years of innovation in industrial, automotive, and communications markets.
The SN74LS126ANSR belongs to TI's legacy 74LS logic family, engineered for robust TTL-compatible bus interfacing in cost-sensitive, reliability-critical industrial and instrumentation applications.
FAQ
What is the operating temperature range for SN74LS126ANSR?
The SN74LS126ANSR is rated for commercial operation from 0°C to +70°C. This range aligns with standard industrial ambient conditions and supports deployment in enclosed control cabinets without forced cooling. Its thermal resistance (θJA = 76°C/W) ensures junction temperatures remain within safe limits under typical 12 mA ICC loading at maximum ambient.
Does SN74LS126ANSR support hot-swap bus isolation?
Yes, the SN74LS126ANSR supports hot-swap bus isolation via its independent active-low 3-state enables (1G–4G). When any G input is held HIGH, the corresponding Y output enters high-impedance mode, decoupling that channel from the bus without affecting others-enabling safe insertion or removal of peripheral modules in live systems.
What is the maximum capacitive load SN74LS126ANSR can drive reliably?
The SN74LS126ANSR is characterized for CL = 45 pF in switching tests, with tPLH/tPHL ≤ 15 ns. In practice, it reliably drives up to 100 pF (e.g., 10 cm of 50 Ω trace + 10 receiver inputs) while maintaining VOL ≤ 0.4 V at 24 mA sink, provided trace impedance is controlled and VCC bypassing is adequate.
How does SN74LS126ANSR differ from SN74LS125ANSR?
The SN74LS126ANSR uses active-low enables (G = LOW enables), whereas SN74LS125ANSR uses active-high enables (G = HIGH enables). Both share identical drive strength, timing, and pinout-but their control logic polarity is inverted, requiring complementary enable signal generation in system firmware or glue logic.
Is SN74LS126ANSR RoHS compliant and what is its lead finish?
Yes, SN74LS126ANSR is RoHS compliant with NiPdAu (nickel-palladium-gold) lead finish. This finish ensures solderability with lead-free reflow profiles (MSL Level-1, peak 260°C), compatibility with no-clean fluxes, and long-term corrosion resistance in humid industrial environments.
SN74LS126ANSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 14-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Logic Type:
- Buffer, Non-Inverting
- Number of Elements:
- 4
- Number of Bits per Element:
- 1
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 2.6mA, 24mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SO
SN74LS126ANSR FAQ
1.How can I place an order for SN74LS126ANSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS126ANSR 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 SN74LS126ANSR reliable?
The price and inventory of SN74LS126ANSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS126ANSR is usually 5 days.
3.What payment methods are accepted for SN74LS126ANSR?
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Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS126ANSR?
SN74LS126ANSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS126ANSR 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 SN74LS126ANSR?
For technical support, including SN74LS126ANSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS126ANSR requirements.
6.How does Aetrix verify that SN74LS126ANSR is sourced from the original manufacturer or authorized distributors?
All SN74LS126ANSR 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 SN74LS126ANSR meets industry standards.
7.What is the process for return or replacement of SN74LS126ANSR?
All SN74LS126ANSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS126ANSR, 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 SN74LS126ANSR part is unused and in its original packaging.
Return procedure for SN74LS126ANSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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