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Texas Instruments SN74HCT157DRE4
- Part No.:
- SN74HCT157DRE4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74HCT157DRE4.pdf
- Description:
- IC MULTIPLEXER 4 X 2:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,575
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Product details
Overview
SN74HCT157DRE4 from Texas Instruments is a high-speed, TTL-compatible quad 2-line-to-1-line data selector/multiplexer in a 16-pin SOIC package. It operates from 4.5 V to 5.5 V, delivers ±6-mA output drive at 5 V, exhibits typical propagation delay of 15 ns (VCC = 5.5 V, CL = 50 pF), and draws ≤80 µA ICC max - enabling reliable signal routing in digital logic control, address/data bus switching, and microcontroller peripheral interfacing.
For engineers reviewing the SN74HCT157DRE4 datasheet, SN74HCT157DRE4 pinout, SN74HCT157DRE4 application, or SN74HCT157DRE4 equivalent, key selection criteria include its dual-input 4-bit multiplexing capability, active-low strobe (G) control, buffered TTL-compatible inputs/outputs, and guaranteed operation across −40°C to 85°C industrial temperature range.
Technical Context
The SN74HCT157DRE4 implements four independent 2:1 multiplexers sharing a common select (A/B) and strobe (G) input. Each Y output reflects the selected A or B input only when G is low; all outputs go high-impedance when G is high. Its HCT logic family ensures CMOS-level power efficiency with TTL-voltage compatibility on inputs.
Internal architecture includes inverters and drivers for full data selection to output gates, with no internal connections on pins 3, 5, and 12 in the D-package variant. Input transition time is specified up to 500 ns, and absolute maximum ratings support robust handling of transient conditions including ±20 mA clamp current and 73°C/W thermal impedance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - compatible with standard 5-V TTL and mixed-voltage logic systems. |
| Propagation Delay (tpd) | 15 ns typical (VCC = 5.5 V, CL = 50 pF) - enables synchronization in sub-20-ns timing-critical digital paths. |
| Output Drive | ±6 mA at 5 V - directly drives up to 15 LSTTL loads without external buffering. |
| Quiescent Current (ICC) | 80 µA max - supports low-static-power system design in always-on or battery-backed logic stages. |
| Input Voltage Compatibility | TTL-level: VIH ≥ 2 V, VIL ≤ 0.8 V - interoperable with legacy 74LS and 74F families without level shifters. |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded control and instrumentation applications. |
| Logic Family | HCT (High-Speed CMOS with TTL input thresholds) - combines CMOS power efficiency with TTL interface robustness. |
Pinout & Package
SN74HCT157DRE4 is housed in a 16-pin SOIC (D) package with 1.27-mm pitch, JEDEC MS-012AC compliant, and RoHS-compliant NiPdAu lead finish. Pin 1 is located in Quadrant Q1 per tape-and-reel orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (G) | Strobe Enable | Active-low global enable: all outputs high-impedance when high; data passes only when low. |
| 2 (A/B) | Data Source Select | Controls which input pair (A or B) routes to each Y output; logic high selects B, low selects A. |
| 3 (NC) | No Internal Connection | Unbonded pin; must be left floating or tied to GND/VCC per layout best practice - no electrical function. |
| 4–7, 9–10, 13–14 (1A–4A, 1B–4B) | Data Inputs | Eight total inputs grouped as four A/B pairs; each pair feeds one multiplexer stage. |
| 8 (GND) | Ground Reference | Primary return path for logic and output current; requires low-impedance PCB connection. |
| 11–12 (NC) | No Internal Connection | Two unconnected pins in D-package; no routing or termination required. |
| 15–16 (1Y–4Y) | Multiplexed Outputs | Four buffered, non-inverted outputs - each reflects selected A/B input when G is asserted. |
| 16 (VCC) | Power Supply | Positive supply rail; bypass capacitor (0.1 µF ceramic) recommended within 10 mm of pin. |
Key Features
| Feature | Design Value |
|---|---|
| Quad 2:1 Multiplexing | Routes four parallel data bits from one of two sources using shared A/B and G controls - reduces control line count in bus arbitration. |
| TTL-Compatible Inputs | Accepts standard TTL voltage thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) while consuming CMOS-level quiescent current - eliminates level-shifting in mixed-family designs. |
| High-Current Outputs | Delivers ±6 mA per output at 5 V - drives multiple LSTTL inputs or small LEDs directly without external buffers. |
| Low-Power Operation | Max ICC = 80 µA at VCC = 5.5 V - suitable for power-sensitive logic stages where static current impacts system budget. |
| Buffered I/O Structure | Input and output buffers isolate internal logic from capacitive loading and noise - improves noise immunity and fanout stability. |
Applications
| Microcontroller Bus Expansion | Digital Test Equipment Signal Routing |
|---|---|
|
Use Scenario: Expanding limited GPIO or address/data lines of an MCU to interface with multiple peripherals (e.g., ADC, DAC, EEPROM). IC Role / Device Role / Timing Role: Quad 2:1 multiplexer enabling dynamic selection between two peripheral banks under software-controlled A/B and G signals. Use Value: Reduces need for additional address decoders or FPGA glue logic while maintaining deterministic 15-ns propagation delay for real-time response. |
Use Scenario: Switching stimulus and measurement paths in automated test equipment (ATE) for multi-channel DUT validation. IC Role / Device Role / Timing Role: Signal routing hub that isolates test channels during calibration or fault injection sequences via strobe-controlled gating. Use Value: Ensures channel isolation with high-impedance outputs when G is high, preventing crosstalk or back-driving during reconfiguration. |
| Industrial PLC I/O Multiplexing | Legacy System Bus Interface Translation |
|
Use Scenario: Consolidating discrete sensor inputs (e.g., limit switches, encoders) onto a shared controller bus in programmable logic controllers. IC Role / Device Role / Timing Role: Digital selector translating parallel sensor status into time-multiplexed bus data under PLC scan-cycle timing. Use Value: Supports −40°C to +85°C operation and tolerates industrial EMI due to buffered I/O and TTL-compatible noise margins. |
Use Scenario: Bridging 74LS-based legacy backplanes with newer 5-V CMOS controllers requiring identical logic-level compatibility. IC Role / Device Role / Timing Role: Level-transparent multiplexer preserving signal integrity across technology generations without added delay or skew. Use Value: Eliminates need for discrete level shifters while maintaining <20 ns timing margin for synchronous bus protocols like ISA or custom parallel interfaces. |
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 |
|---|---|---|---|
| SN74HCT257D | Identical pinout and logic function but features three-state outputs (active-high enable); SN74HCT157DRE4 uses active-low strobe and non-three-state outputs. | Required where bus-sharing with tristate arbitration is needed; not drop-in for SN74HCT157DRE4 without enable logic redesign. | Select SN74HCT257D only if system demands output disable capability beyond simple gating. |
| 74ACT157DR | Same pinout and function but ACT family: higher speed (tpd ≈ 9 ns), higher drive (±24 mA), and wider VCC range (4.5–5.5 V same), but higher ICC (max 4 mA). | Better suited for high-frequency clock distribution or driving heavier capacitive loads; less optimal for ultra-low-quiescent-current designs. | Choose 74ACT157DR when propagation delay <12 ns or output current >±6 mA is mandatory. |
Compared with SN74HCT257D and 74ACT157DR, SN74HCT157DRE4 offers the lowest static power (80 µA max) and simplest enable logic (single active-low strobe), making it optimal for cost-sensitive, thermally constrained, or legacy-compatible industrial control designs where moderate speed suffices.
Availability
SN74HCT157DRE4 is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, microcontroller peripheral multiplexing, and legacy bus interface translation requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74HCT157DRE4 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 decades of heritage in industry-standard logic families.
The SN74HCT157DRE4 belongs to TI's HCT logic series, designed specifically to provide TTL-compatible interface performance with CMOS power efficiency for industrial, automotive, and communications infrastructure applications.
FAQ
What is the function of the G (strobe) pin on the SN74HCT157DRE4?
The G pin on the SN74HCT157DRE4 is an active-low strobe enable input. When G is low, the selected A/B inputs pass through to the corresponding Y outputs; when G is high, all four Y outputs enter a high-impedance state. This allows the SN74HCT157DRE4 to gate data flow synchronously without requiring individual output disables, simplifying bus arbitration in shared-data-path systems.
Does the SN74HCT157DRE4 support mixed-voltage operation below 4.5 V?
No, the SN74HCT157DRE4 does not support operation below 4.5 V. Its recommended operating voltage range is strictly 4.5 V to 5.5 V, and input thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) are specified only within this range. Operating the SN74HCT157DRE4 at 3.3 V or lower risks undefined logic states, increased propagation delay, and potential failure to meet TTL compatibility guarantees.
How many unused inputs must be terminated on the SN74HCT157DRE4, and how?
All unused inputs on the SN74HCT157DRE4 - including A/B, G, and any unconnected 1A–4A/1B–4B lines - must be held at a valid logic level (VCC or GND) to prevent floating nodes, increased ICC, and erratic output behavior. TI recommends tying them directly to VCC or GND via short PCB traces; pull-up/down resistors are acceptable but not required unless signal integrity analysis indicates noise susceptibility.
Is the SN74HCT157DRE4 pin-compatible with the SN74LS157N?
No, the SN74HCT157DRE4 is not pin-compatible with the SN74LS157N. While both perform quad 2:1 multiplexing and share functional equivalence, the SN74LS157N uses a 16-pin PDIP (N) package with different pin assignments - notably, G is on pin 5 and A/B on pin 1 in LS157, versus G on pin 1 and A/B on pin 2 in the D-package SN74HCT157DRE4. Physical replacement requires PCB redesign.
What is the maximum capacitive load the SN74HCT157DRE4 can drive while maintaining specified tpd?
The SN74HCT157DRE4's specified propagation delay (tpd = 15 ns typical) is validated at CL = 50 pF. At CL = 150 pF, tpd increases to 19 ns (VCC = 5.5 V). While the device can drive higher capacitance, timing margins degrade linearly beyond 150 pF; for designs requiring strict <20 ns delay, total load (including trace and input capacitance) should remain ≤150 pF. The SN74HCT157DRE4 itself contributes ~10 pF input capacitance (Ci).
SN74HCT157DRE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- 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:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
SN74HCT157DRE4 FAQ
1.How can I place an order for SN74HCT157DRE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT157DRE4 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 SN74HCT157DRE4 reliable?
The price and inventory of SN74HCT157DRE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT157DRE4 is usually 5 days.
3.What payment methods are accepted for SN74HCT157DRE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT157DRE4 transactions.
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4.How is shipping managed for SN74HCT157DRE4?
SN74HCT157DRE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT157DRE4 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 SN74HCT157DRE4?
For technical support, including SN74HCT157DRE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT157DRE4 requirements.
6.How does Aetrix verify that SN74HCT157DRE4 is sourced from the original manufacturer or authorized distributors?
All SN74HCT157DRE4 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 SN74HCT157DRE4 meets industry standards.
7.What is the process for return or replacement of SN74HCT157DRE4?
All SN74HCT157DRE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT157DRE4, 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 SN74HCT157DRE4 part is unused and in its original packaging.
Return procedure for SN74HCT157DRE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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