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Texas Instruments CD74HCT251M96
- Part No.:
- CD74HCT251M96
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
CD74HCT251M96.pdf
- Description:
- IC MULTIPLEXER 1 X 8:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,732
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Product details
Overview
CD74HCT251M96 from Texas Instruments is an 8-input, three-state digital multiplexer with true (Y) and complement (Y̅) outputs, designed for bus-oriented systems. It operates at 4.5 V to 5.5 V, delivers 12 ns typical data-to-output propagation delay at 5 V/15 pF, drives 10 LSTTL loads, and supports full industrial temperature range (–55 °C to 125 °C).
For engineers reviewing the CD74HCT251M96 datasheet, CD74HCT251M96 pinout, CD74HCT251M96 application, or CD74HCT251M96 equivalent, this device serves as a direct functional and pin-compatible replacement for the 74LS251 in TTL-interfaced logic systems requiring low-power CMOS performance, bus isolation via three-state control, and simultaneous true/complement output delivery.
Technical Context
The CD74HCT251M96 implements an 8:1 multiplexing function using high-speed silicon-gate CMOS technology, with address decoding across S2–S0 inputs to select one of eight data inputs (I0–I7). Its three-state output enable (OE) input controls bidirectional bus compatibility by placing both Y and Y̅ outputs into high-impedance when OE = HIGH.
It features LSTTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V), CMOS-level output drive capability, and balanced transition times (15 ns typical), ensuring clean signal routing without skew-induced timing violations in synchronous data paths.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures direct drop-in replacement for 5 V TTL systems without level-shifting. |
| tpd (Data to Y/Y̅) | 12 ns typ @ 5 V, CL = 15 pF - Enables reliable operation in 25 MHz+ address/data selection cycles. |
| IOH/IOL Drive | ±6 mA @ VOH/VOL - Sufficient to directly drive 10 LSTTL loads without buffer amplification. |
| Operating Temp | –55 °C to 125 °C - Qualified for extended industrial, automotive under-hood, and military-grade environments. |
| Three-State Leakage | ±5 μA max @ 125 °C - Guarantees minimal bus contention current during high-Z state in multi-driver configurations. |
| Input Capacitance | 10 pF - Low loading preserves signal integrity on shared select/address lines with minimal RC delay. |
| Power Dissipation Cap | 60 pF - Enables accurate dynamic power estimation (PD = VCC² × f × (Cpd + CL)) for thermal design. |
Pinout & Package
CD74HCT251M96 is housed in a 16-pin SOIC (D) package (9.90 mm × 3.90 mm body size), RoHS-compliant, with NIPDAU/SN lead finish and moisture sensitivity level 1 (260 °C reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (I0) | Data Input 0 | Low-order data channel selected when S2S1S0 = 000; CMOS-compatible input with ≤1 μA leakage. |
| 2 (I1) | Data Input 1 | Second data channel selected at S2S1S0 = 001; identical electrical specs to I0–I7. |
| 3 (I2) | Data Input 2 | Third data channel selected at S2S1S0 = 010; shares same noise immunity (30% VCC) as all inputs. |
| 4 (I3) | Data Input 3 | Fourth data channel selected at S2S1S0 = 011; supports full –55 °C to 125 °C operation. |
| 5 (I4) | Data Input 4 | Fifth data channel selected at S2S1S0 = 100; TTL-compatible input thresholds apply. |
| 6 (I5) | Data Input 5 | Sixth data channel selected at S2S1S0 = 101; no external pull-up required for unused inputs. |
| 7 (I6) | Data Input 6 | Seventh data channel selected at S2S1S0 = 110; driven from standard logic sources. |
| 8 (I7) | Data Input 7 | Highest-order data channel selected at S2S1S0 = 111; matches propagation delay spec of 12 ns typ. |
| 9 (GND) | Ground Reference | Primary return path for all internal logic and output currents; must be low-impedance. |
| 10 (Y) | True Output | Active-high selected data output; enters high-Z when OE = HIGH; drives bus directly. |
| 11 (Y̅) | Complement Output | Inverted version of Y; simultaneously available; same timing and drive strength as Y. |
| 12 (OE) | Output Enable | Active-low control: OE = LOW enables Y/Y̅; OE = HIGH forces both into high-impedance. |
| 13 (S0) | Select Bit 0 | LSB of 3-bit address bus; TTL-compatible input; determines modulo-2 selection bit. |
| 14 (S1) | Select Bit 1 | Middle bit of address bus; defines 2× grouping of inputs; matched delay to S0/S2. |
| 15 (S2) | Select Bit 2 | MSB of address bus; selects upper/lower half of I0–I7; fully specified over full temp range. |
| 16 (VCC) | Supply Voltage | +5 V nominal supply; bypass capacitor (0.1 μF) required adjacent to pin for noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| True and complement outputs | Simultaneous Y and Y̅ delivery eliminates need for external inverters in differential-sense or parity-check circuits. |
| Three-state output capability | Enables direct connection to shared data buses without contention; OE-controlled high-Z state isolates outputs cleanly. |
| LSTTL input compatibility | VIL ≤ 0.8 V and VIH ≥ 2.0 V allow seamless interface with legacy 74LS logic without level translators. |
| Low dynamic power consumption | CMOS core reduces ICC to 8–160 μA (vs. >10 mA for LS251), cutting board-level heat and supply load. |
| Balanced propagation and transition times | tpd = 12 ns and tt = 15 ns ensure minimal duty-cycle distortion in clock/data distribution networks. |
Applications
| Microprocessor Address Decoding | Programmable Logic Interface |
|---|---|
Use Scenario: Selecting between multiple memory-mapped peripherals (e.g., UART, SPI, GPIO) using A0–A2 address lines. IC Role / Device Role / Timing Role: Acts as address-space router, translating 3-bit address into one active peripheral enable signal. Use Value: Eliminates discrete gate logic; provides deterministic 12 ns selection latency and bus-isolated enable outputs. | Use Scenario: Configuring signal routing in FPGA/CPLD I/O banks where true/complement outputs feed parallel logic paths. IC Role / Device Role / Timing Role: Provides synchronized dual-polarity data selection for combinational logic synthesis. Use Value: Reduces LUT count by delivering Y/Y̅ simultaneously; avoids added inverter delay in critical paths. |
| Industrial Bus Arbitration | Digital Test Equipment Multiplexing |
Use Scenario: Managing shared RS-485 or CAN transceiver control lines across multiple sensor nodes on a single bus segment. IC Role / Device Role / Timing Role: Routes node-specific control signals onto common bus-enable lines with precise timing alignment. Use Value: Enables deterministic arbitration sequencing; three-state outputs prevent bus conflicts during handover. | Use Scenario: Scanning 8-channel analog front-end inputs through a single ADC using digital control. IC Role / Device Role / Timing Role: Serves as digitally controlled analog signal selector, with OE synchronized to ADC conversion start. Use Value: Delivers sub-20 ns switching window; complements Y/Y̅ support allows differential sampling architectures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-input multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT251N | Same logic function, pinout, and specs; PDIP-16 package instead of SOIC-16. | Through-hole mounting; higher thermal resistance (RθJA = 73 °C/W vs. 67 °C/W); no tape-and-reel option. | Choose SN74HCT251N for prototyping or low-volume through-hole assembly where reflow isn't used. |
| 74ACT251SCX | Faster tpd (8 ns typ), higher drive (±24 mA), wider VCC (4.5–5.5 V), but higher ICC (40 μA typ vs. 8 μA). | Higher speed/power trade-off; not drop-in due to different AC characteristics and layout-sensitive noise behavior. | Choose 74ACT251SCX only when <10 ns propagation delay is mandatory and board-level noise margin permits. |
Compared with SN74HCT251N and 74ACT251SCX, CD74HCT251M96 offers optimal balance of industrial temperature range, SOIC packaging for automated assembly, ultra-low static current, and guaranteed LSTTL compatibility-making it the preferred choice for cost-sensitive, high-reliability bus-interface designs.
Availability
CD74HCT251M96 is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, and test instrumentation requiring stable component supply, long-term lifecycle support, and RoHS-compliant SOIC packaging.
Supply support for CD74HCT251M96 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 50 years of innovation in high-reliability logic families.
CD74HCT251M96 belongs to TI's HCT logic series-designed specifically for seamless migration from bipolar TTL into low-power CMOS while preserving pinout, voltage thresholds, and timing behavior for drop-in replacement.
FAQ
What is the maximum clock/data frequency supported by CD74HCT251M96?
The CD74HCT251M96 does not operate on a clock; it is combinatorial. Its 12 ns typical propagation delay (data to Y/Y̅) supports reliable operation up to ~25 MHz in synchronous selection systems when paired with appropriate setup/hold margins. Maximum usable frequency depends on system-level timing constraints, not an internal clock.
Does CD74HCT251M96 require external pull-up resistors on its inputs?
No. CD74HCT251M96 inputs have CMOS-compatible leakage (≤1 μA) and defined TTL thresholds; all unused inputs must be tied to VCC or GND per TI SCBA004 guidelines-but no pull-up resistors are needed. Floating inputs cause undefined operation and increased ICC.
Can CD74HCT251M96 drive a 50-pF load while maintaining its specified propagation delay?
Yes. The 12 ns typical tpd is measured at CL = 15 pF, but the datasheet specifies switching characteristics up to CL = 50 pF (max tpd = 53 ns at –40 °C to 85 °C). Performance remains within specification at 50 pF, though delay increases predictably per capacitive loading.
Is CD74HCT251M96 pin-compatible with the obsolete 74LS251?
Yes. CD74HCT251M96 is explicitly designed as a functionally and pin-compatible replacement for the 74LS251, matching pin assignments, truth table, and DC/AC electrical behavior-including identical S0–S2, I0–I7, Y, Y̅, OE, VCC, and GND locations in the 16-pin SOIC footprint.
What is the purpose of the Y̅ (complement) output on CD74HCT251M96?
The Y̅ output delivers the logical inverse of the selected input simultaneously with Y, enabling single-cycle parity generation, differential signaling, or dual-rail logic without external inverters. This reduces component count and eliminates inverter-induced skew in time-critical paths involving CD74HCT251M96.
CD74HCT251M96 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:
- Active
- Type:
- Multiplexer
- Circuit:
- 1 x 8:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 4mA, 4mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
CD74HCT251M96 FAQ
1.How can I place an order for CD74HCT251M96 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT251M96 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 CD74HCT251M96 reliable?
The price and inventory of CD74HCT251M96 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT251M96 is usually 5 days.
3.What payment methods are accepted for CD74HCT251M96?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT251M96 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT251M96?
CD74HCT251M96 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT251M96 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 CD74HCT251M96?
For technical support, including CD74HCT251M96 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT251M96 requirements.
6.How does Aetrix verify that CD74HCT251M96 is sourced from the original manufacturer or authorized distributors?
All CD74HCT251M96 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 CD74HCT251M96 meets industry standards.
7.What is the process for return or replacement of CD74HCT251M96?
All CD74HCT251M96 units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT251M96, 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 CD74HCT251M96 part is unused and in its original packaging.
Return procedure for CD74HCT251M96:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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