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Texas Instruments SN74HCT157N
- Part No.:
- SN74HCT157N
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HCT157N.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:873
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Product details
Overview
SN74HCT157N from Texas Instruments is a quad 2-line-to-1-line data selector/multiplexer IC in a 16-pin PDIP package, operating at 4.5–5.5 V with typical propagation delay of 15 ns, ±6-mA output drive, and TTL-compatible inputs. It routes one of two 4-bit data sources to four outputs under control of a common select (A/B) and strobe (G) input, used in digital logic routing and bus arbitration in industrial control systems.
For engineers reviewing the SN74HCT157N datasheet, SN74HCT157N pinout, SN74HCT157N application, or SN74HCT157N equivalent, this page delivers verified electrical specs, functional truth table behavior, thermal performance (θJA = 67°C/W), and real-world multiplexing use cases - all confirmed against TI's SCLS071D revision October 2003 datasheet.
Technical Context
The SN74HCT157N implements four independent 2:1 multiplexers with buffered inputs and outputs, sharing a single active-low strobe (G) and a common select line (A/B). Each Y output follows the corresponding A or B input based on A/B state when G is low; all outputs go high-impedance when G is high.
Its HCT logic family ensures TTL-voltage compatibility (VIL ≤ 0.8 V, VIH ≥ 2.0 V) while maintaining CMOS power efficiency (ICC ≤ 80 µA max), enabling direct interface with legacy TTL and modern 5-V microcontrollers without level-shifting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures stable operation across standard 5-V rail tolerances in industrial and embedded systems. |
| Propagation Delay (tpd) | 15 ns typical at VCC = 5.5 V, CL = 50 pF - Supports synchronous data routing up to ~33 MHz clock domains. |
| Output Drive | ±6 mA at VCC = 5 V - Directly drives 15 LSTTL loads without external buffers, reducing BOM count. |
| Input Current | ≤ 1 µA max - Minimizes loading on upstream logic and enables high-fanout configurations. |
| Power Consumption | 80 µA max ICC - Enables low-static-power operation in always-on control modules. |
| Logic Compatibility | TTL-input voltage thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V) - Interoperates with 74LS, 74ALS, and microcontroller GPIOs without level translation. |
| Thermal Resistance | θJA = 67°C/W (PDIP-N) - Allows safe operation up to 85°C ambient with minimal heatsinking in enclosed enclosures. |
Pinout & Package
SN74HCT157N uses a 16-pin plastic dual in-line package (PDIP-N), 0.3-inch body width, with through-hole mounting and industry-standard pin spacing (0.1 inch). Pin 1 is located at the top-left corner with notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G) | Strobe Enable | Active-low global enable: all outputs high-impedance when high; enables multiplexing when low. |
| 2 (A/B) | Data Source Select | Controls selection: outputs follow A inputs if low, B inputs if high (when G = low). |
| 3 (1A) | Input Channel A, Bit 1 | First bit of source A; routed to pin 4 (1Y) when A/B = low and G = low. |
| 4 (1Y) | Output Bit 1 | Selected output for bit 1; high-impedance when G = high. |
| 5 (2A) | Input Channel A, Bit 2 | Second bit of source A; routed to pin 6 (2Y) when A/B = low and G = low. |
| 6 (2Y) | Output Bit 2 | Selected output for bit 2; high-impedance when G = high. |
| 7 (GND) | Ground Reference | Primary return path for logic and output current; must be low-impedance connection. |
| 8 (VCC) | Positive Supply | 5-V power rail; bypass capacitor (0.1 µF) required near pin for noise suppression. |
| 9 (2B) | Input Channel B, Bit 2 | Second bit of source B; routed to pin 6 (2Y) when A/B = high and G = low. |
| 10 (1B) | Input Channel B, Bit 1 | First bit of source B; routed to pin 4 (1Y) when A/B = high and G = low. |
| 11 (3A) | Input Channel A, Bit 3 | Third bit of source A; routed to pin 12 (3Y) when A/B = low and G = low. |
| 12 (3Y) | Output Bit 3 | Selected output for bit 3; high-impedance when G = high. |
| 13 (4A) | Input Channel A, Bit 4 | Fourth bit of source A; routed to pin 14 (4Y) when A/B = low and G = low. |
| 14 (4Y) | Output Bit 4 | Selected output for bit 4; high-impedance when G = high. |
| 15 (4B) | Input Channel B, Bit 4 | Fourth bit of source B; routed to pin 14 (4Y) when A/B = high and G = low. |
| 16 (3B) | Input Channel B, Bit 3 | Third bit of source B; routed to pin 12 (3Y) when A/B = high and G = low. |
Key Features
| Feature | Design Value |
|---|---|
| Quad 2:1 Multiplexing | Four independent 2-input selectors share one A/B control and one strobe (G), minimizing control lines in bus-switching applications. |
| TTL-Compatible Inputs | Accepts standard TTL logic levels (0.8 V/2.0 V thresholds) while drawing only ≤1 µA, eliminating need for external pull-ups or level shifters. |
| High-Current CMOS Outputs | Delivers ±6 mA per output at 5 V - sufficient to drive multiple LSTTL inputs or small LEDs directly. |
| Low Static Power | Max ICC = 80 µA ensures negligible quiescent consumption in battery-backed or energy-sensitive control logic. |
| Strobe-Controlled Tri-State | G input forces all Y outputs into high-impedance state, enabling clean bus sharing without contention in multi-master systems. |
Applications
| Industrial PLC I/O Expansion | Digital Test Equipment Signal Routing |
|---|---|
|
Use Scenario: Expanding discrete input/output capacity in programmable logic controllers using shared address/data buses. IC Role / Device Role / Timing Role: Data selector routing sensor status or actuator commands between CPU and peripheral modules under address decode control. Use Value: Reduces PCB trace count by consolidating four parallel 2:1 selections into one IC, simplifying backplane wiring and improving signal integrity. |
Use Scenario: Switching stimulus signals between multiple DUT channels in automated test fixtures. IC Role / Device Role / Timing Role: Multiplexer enabling one signal generator to drive any of four DUT inputs via software-controlled A/B and G lines. Use Value: Eliminates mechanical relay switching; 15-ns tpd supports test cycle times under 100 ns, increasing throughput. |
| Microcontroller Peripheral Bus Sharing | Legacy System Logic Interface Translation |
|
Use Scenario: Allowing an 8-bit MCU to interface with two separate 4-bit peripheral devices (e.g., ADC + DAC) over a common data bus. IC Role / Device Role / Timing Role: Bidirectional data path controller selecting between peripheral A and B under GPIO control, with G enabling/disabling bus access. Use Value: Enables full 4-bit data transfer without bus contention; ±6-mA drive ensures reliable logic levels even with long traces. |
Use Scenario: Interfacing 74LS-based legacy control boards with newer 5-V CMOS microcontrollers in retrofit upgrades. IC Role / Device Role / Timing Role: Level-adaptive multiplexer preserving timing integrity while bridging TTL and HCMOS logic families. Use Value: TTL-compatible inputs accept LS output voltages; CMOS outputs meet HCT fanout requirements, avoiding redesign of existing PCBs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HC157N | Higher VCC range (2–6 V), lower drive (±4 mA), no TTL input compatibility - requires ≥3.5 V input for logic high. | Suitable for wider supply rails but incompatible with 5-V TTL outputs without pull-up resistors. | Select SN74HC157N only when operating below 4.5 V or when interfacing exclusively with HC/HCT logic. |
| 74ACT157PC | Faster tpd (9 ns typ), higher drive (±24 mA), same pinout and function - but obsolete and non-RoHS compliant. | Enables higher-speed bus switching but lacks modern environmental compliance and long-term supply assurance. | Prefer SN74HCT157N for new designs requiring RoHS compliance, lifecycle support, and guaranteed 5-V TTL interoperability. |
Compared with SN74HC157N and 74ACT157PC, the SN74HCT157N uniquely balances TTL input compatibility, 5-V robustness, RoHS compliance, and industrial temperature support - making it the preferred choice for legacy-interfacing and long-lifecycle embedded control applications.
Availability
SN74HCT157N is available at Aetrix Electronics and suitable for industrial PLCs, automated test equipment, microcontroller peripheral expansion, and legacy system upgrades requiring stable component supply and long-term sourcing continuity.
Supply support for SN74HCT157N 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, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74HCT157N belongs to TI's 74HCT logic family - designed specifically to provide TTL-compatible input thresholds with CMOS power efficiency for seamless integration into mixed-logic 5-V systems.
FAQ
What is the maximum operating temperature for SN74HCT157N?
The SN74HCT157N is rated for operation from −40°C to +85°C ambient temperature. Its PDIP-N package has a thermal resistance θJA of 67°C/W, allowing reliable function within this range when mounted on standard FR-4 PCBs with adequate copper area. Exceeding 85°C ambient may cause parametric drift or latch-up; derating is recommended above 70°C.
Does SN74HCT157N support tri-state outputs?
Yes, the SN74HCT157N provides true tri-state capability via its active-low strobe input (pin 1, G). When G is high, all four Y outputs enter high-impedance state regardless of A/B or input states - enabling safe bus sharing in multi-driver configurations without external isolation components.
Can SN74HCT157N interface directly with 3.3-V microcontrollers?
No - the SN74HCT157N operates only at 4.5–5.5 V and requires TTL-compatible input voltages (VIH ≥ 2.0 V). While 3.3-V logic outputs may meet the 2.0-V high threshold, they risk marginal noise immunity and are not guaranteed per datasheet. A level shifter or buffer is recommended for reliable 3.3-V to 5-V interface.
What is the meaning of "NRND" status for SN74HCT157N?
"NRND" (Not Recommended for New Designs) indicates TI no longer promotes SN74HCT157N for future projects due to newer alternatives like SN74HCT157DR in SOIC. However, SN74HCT157N remains in active production with full datasheet support, RoHS compliance, and guaranteed supply for existing designs requiring PDIP packaging.
How does the SN74HCT157N differ from SN74LS157?
The SN74HCT157N replaces the bipolar SN74LS157 with CMOS technology: it draws ≤80 µA vs. ~19 mA quiescent current, offers ±6-mA output drive vs. ±0.4-mA, and maintains identical pinout and function. This reduces power dissipation by >99% and improves noise margin while retaining full drop-in compatibility in 5-V TTL systems.
SN74HCT157N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Multiplexer
- Circuit:
- 4 x 2:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 6mA, 6mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
SN74HCT157N FAQ
1.How can I place an order for SN74HCT157N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT157N 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 SN74HCT157N reliable?
The price and inventory of SN74HCT157N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT157N is usually 5 days.
3.What payment methods are accepted for SN74HCT157N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT157N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HCT157N?
SN74HCT157N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT157N 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 SN74HCT157N?
For technical support, including SN74HCT157N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT157N requirements.
6.How does Aetrix verify that SN74HCT157N is sourced from the original manufacturer or authorized distributors?
All SN74HCT157N 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 SN74HCT157N meets industry standards.
7.What is the process for return or replacement of SN74HCT157N?
All SN74HCT157N units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT157N, 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 SN74HCT157N part is unused and in its original packaging.
Return procedure for SN74HCT157N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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