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Texas Instruments SN74AHCT157D
- Part No.:
- SN74AHCT157D
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74AHCT157D.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:720
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Product details
Overview
SN74AHCT157D from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer IC operating at 4.5V–5.5V VCC, featuring TTL-voltage-compatible inputs, active-low strobe (G) control, and true (non-inverted) outputs. It routes one of two 4-bit input sources to four outputs based on a common select line, enabling compact data path arbitration in digital logic systems such as address/data bus switching in microcontroller peripherals.
For engineers reviewing the SN74AHCT157D datasheet, SN74AHCT157D pinout, SN74AHCT157D application, or SN74AHCT157D equivalent, this device serves as a high-speed, low-power multiplexing solution with verified 7.5 ns typical propagation delay (CL = 15 pF), ±8 mA output drive, and industrial temperature range (–40°C to +85°C) compatibility.
Technical Context
The SN74AHCT157D implements positive-logic 4-channel 2:1 multiplexing using standard CMOS circuitry with TTL-level input thresholds (VIL = 0.8 V, VIH = 2.0 V). Its functional block includes four independent selector units sharing a single active-low strobe (G) that forces all Y outputs low when asserted.
Each channel selects between A and B inputs based on the state of the common A/B select line; when G is low, the selected 4-bit word appears unaltered at outputs 1Y–4Y. The device exhibits latch-up immunity exceeding 250 mA per JESD17 and supports noise margins up to 0.4 V (VOL(P)) under dynamic load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures stable operation across standard 5 V logic rails with ±5% tolerance. |
| Propagation Delay (tPLH/tPHL) | 7.5 ns max (CL = 15 pF) - Enables reliable timing in 100+ MHz data-path switching applications. |
| Output Drive (IOH/IOL) | ±8 mA - Sufficient to directly drive multiple 74-series TTL/CMOS inputs without buffering. |
| Input Voltage Compatibility | TTL-level (VIH = 2.0 V, VIL = 0.8 V) - Allows seamless interfacing with legacy 5 V TTL logic families. |
| Operating Temperature | –40°C to +85°C - Qualified for industrial environments including motor control, instrumentation, and PLC I/O modules. |
| Power Dissipation Capacitance (Cpd) | 11 pF - Predicts dynamic power consumption (Pdyn ≈ Cpd × VCC² × f) for clocked applications. |
Pinout & Package
SN74AHCT157D uses a 16-pin SOIC (D) package measuring 6.2 mm × 10.3 mm body size, with 1.27 mm lead pitch and gull-wing leads. Thermal resistance RθJA is 73 °C/W, supporting moderate-power logic integration without forced cooling.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | A/B Select | Common address line determining whether A or B inputs are routed to outputs. |
| 2–3, 5–6, 10–11, 13–14 | Data Inputs (1A/1B through 4A/4B) | Eight total inputs grouped into four independent 2:1 channels. |
| 4, 7, 9, 12 | Data Outputs (1Y–4Y) | True (non-inverted) outputs reflecting selected A or B input per channel. |
| 8 | GND | Logic ground reference for all internal circuitry and I/O. |
| 15 | G (Strobe) | Active-low enable: outputs go low when high; enables multiplexing only when low. |
| 16 | VCC | Positive supply rail (4.5–5.5 V); requires local 0.1 µF bypass capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-input compatibility | Accepts standard 5 V TTL logic levels without level-shifting, simplifying mixed-family system design. |
| Common strobe control (G) | Single-pin global enable/disable allows synchronized gating of all four channels in real-time control paths. |
| True output logic | Delivers non-inverted data - eliminates need for external inverters in signal routing where polarity must be preserved. |
| Latch-up immunity | Exceeds 250 mA per JESD17 - ensures robustness against transient current faults in noisy industrial environments. |
Applications
| Microcontroller Address/Data Bus Switching | Industrial PLC I/O Multiplexing |
|---|---|
Use Scenario: A microcontroller with limited GPIO routes shared address/data lines to multiple peripheral devices (e.g., EEPROM, ADC, display driver) via time-division. IC Role / Device Role / Timing Role: SN74AHCT157D acts as a 4-bit bidirectional bus switch controller, selecting between two peripheral data sources under software-controlled A/B and G signals. Use Value: Reduces PCB trace count by 50% versus discrete routing, while maintaining full 5 V logic compatibility and sub-10 ns timing precision. |
Use Scenario: A programmable logic controller consolidates analog sensor inputs (temperature, pressure, flow) onto a single ADC channel using time-sliced sampling. IC Role / Device Role / Timing Role: SN74AHCT157D functions as a front-end analog multiplexer driver, conditioning and selecting four sensor signals before digitization. Use Value: Enables cost-effective 4-channel analog acquisition with deterministic 7.5 ns channel-switch latency and no external biasing components. |
| Digital Test Equipment Signal Routing | Legacy System Interface Adapter |
Use Scenario: Automated test equipment routes stimulus signals from multiple pattern generators to DUT pins based on test sequence commands. IC Role / Device Role / Timing Role: SN74AHCT157D serves as a reconfigurable 4-bit signal path selector, controlled by FPGA-generated A/B and G signals synchronized to test clock edges. Use Value: Provides deterministic, glitch-free signal routing with verified 0.4 V dynamic noise margin - critical for high-fidelity waveform integrity. |
Use Scenario: Retrofitting a modern MCU into an older 5 V TTL-based system requiring compatibility with existing bus drivers and latches. IC Role / Device Role / Timing Role: SN74AHCT157D bridges voltage and timing domains as a protocol-transparent data selector between new and legacy subsystems. Use Value: Eliminates need for discrete level shifters or custom gate arrays while preserving original timing budgets and signal integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 4-channel 2:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT157DR | Same silicon die and electrical specs; differs only in tape-and-reel packaging (2500 pcs/reel vs. tube). | Identical functionality and pinout - suitable for automated SMT assembly instead of manual prototyping. | Select SN74AHCT157DR for volume production; SN74AHCT157D remains valid for evaluation and low-volume builds. |
| SN74LV157A | Lower VCC range (2.0–5.5 V), reduced drive (±6 mA), higher tPD (11 ns max), and LV-CMOS input thresholds. | Better suited for mixed-voltage systems (e.g., 3.3 V core + 5 V interface) but not drop-in compatible with strict TTL input requirements. | Choose SN74LV157A only if supply flexibility or lower static current (<1 µA) outweighs need for guaranteed TTL compatibility. |
Compared with SN74AHCT157DR, SN74AHCT157D offers identical logic performance but requires manual handling; versus SN74LV157A, it delivers superior noise immunity and guaranteed TTL interoperability at the cost of narrower supply range and higher quiescent current.
Availability
SN74AHCT157D is available at Aetrix Electronics and suitable for industrial automation, test equipment, and legacy system upgrades requiring stable component supply, long-term obsolescence management, and full traceability.
Supply support for SN74AHCT157D 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 company founded in 1930, specializing in analog and embedded processing technologies with broad manufacturing scale and automotive-grade qualification capabilities.
The SN74AHCT157D belongs to TI's 74AHCT logic family, designed specifically for high-speed, TTL-compatible 5 V digital systems requiring robust noise immunity, latch-up resistance, and industrial temperature operation.
FAQ
What is the maximum propagation delay of the SN74AHCT157D at 5 V supply?
The SN74AHCT157D has a maximum propagation delay of 7.5 ns (tPLH/tPHL) under recommended conditions (VCC = 5 V, TA = 25°C, CL = 15 pF). This value is confirmed in Section 4.5 of the official TI datasheet SCLS347L and applies to all four channels when strobe (G) is active low.
Does the SN74AHCT157D support 3.3 V logic inputs?
No - the SN74AHCT157D requires TTL-compatible input thresholds: VIL ≤ 0.8 V and VIH ≥ 2.0 V. While it may function with 3.3 V CMOS outputs in some cases, TI does not guarantee operation below VCC × 0.6, and marginal noise margins increase risk of metastability. For 3.3 V systems, consider SN74LV157A instead.
Can unused inputs on the SN74AHCT157D be left floating?
No - all unused inputs on the SN74AHCT157D must be tied to VCC or GND to prevent undefined logic states and excessive ICC current. TI explicitly recommends this in Section 4.2 and Figure 7-1 of the datasheet; floating inputs cause unpredictable output behavior and increased power consumption due to internal transistor contention.
What is the thermal resistance (RθJA) of the SN74AHCT157D package?
The SN74AHCT157D in its SOIC (D) package has a junction-to-ambient thermal resistance (RθJA) of 73 °C/W, as specified in Table 4-3 of the TI datasheet SCLS347L. This value assumes standard JEDEC 2S2P board conditions and supports continuous operation up to +85°C ambient without heatsinking.
Is the SN74AHCT157D pin-compatible with the SN74LS157?
Yes - the SN74AHCT157D shares identical pinout, function table, and logic behavior with the bipolar SN74LS157, including A/B select, strobe (G), and 1Y–4Y outputs. However, SN74AHCT157D offers CMOS advantages: lower ICC (20 µA max), higher noise immunity, and improved latch-up performance - making it a direct upgrade replacement.
SN74AHCT157D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 8mA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74AHCT157D FAQ
1.How can I place an order for SN74AHCT157D through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT157D 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 SN74AHCT157D reliable?
The price and inventory of SN74AHCT157D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT157D is usually 5 days.
3.What payment methods are accepted for SN74AHCT157D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT157D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT157D?
SN74AHCT157D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT157D 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 SN74AHCT157D?
For technical support, including SN74AHCT157D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT157D requirements.
6.How does Aetrix verify that SN74AHCT157D is sourced from the original manufacturer or authorized distributors?
All SN74AHCT157D 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 SN74AHCT157D meets industry standards.
7.What is the process for return or replacement of SN74AHCT157D?
All SN74AHCT157D units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT157D, 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 SN74AHCT157D part is unused and in its original packaging.
Return procedure for SN74AHCT157D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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