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Texas Instruments CD74AC251MG4
- Part No.:
- CD74AC251MG4
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
CD74AC251MG4.pdf
- Description:
- IC MULTIPLEXER 1 X 8:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,046
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Product details
Overview
CD74AC251MG4 from Texas Instruments is an 8-input, three-state CMOS multiplexer with true (Y) and complement (Y̅) outputs, 5.5V max supply voltage, ±24mA output drive, and 6ns typical propagation delay at 5V/25°C/50pF - used for data routing in digital control logic, address selection, and signal gating in industrial microcontroller interfaces.
For engineers reviewing the CD74AC251MG4 datasheet, CD74AC251MG4 pinout, CD74AC251MG4 application, or CD74AC251MG4 equivalent, key selection criteria include its 16-pin SOIC package, dual-output capability, wide 1.5V–5.5V operating range, ESD-hardened design (2kV MIL-STD-883), and balanced noise immunity at 30% of VCC.
Technical Context
The CD74AC251MG4 implements a single 8:1 data selector using Harris Advanced CMOS Logic, with independent S0–S2 address inputs controlling which of eight data inputs (I0–I7) appears at Y and Y̅ outputs. Output Enable (OE) is active-low and places both outputs in high-impedance state when asserted.
It features SCR-latchup-resistant process technology, buffered inputs, and balanced propagation delays between data and select paths - enabling reliable timing-critical switching in mixed-voltage systems where 3.3V and 5V logic coexist.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 1.5V to 5.5V - supports direct interface with 1.8V, 3.3V, and 5V logic families without level shifters. |
| Propagation Delay (tPLH/tPHL) | 12.3ns max at 5V, -55°C to +125°C - ensures predictable timing in real-time control loops. |
| Output Drive Strength | ±24mA per output - drives 15 FAST™ ICs or 50Ω transmission lines directly, reducing external buffer count. |
| Input/Output Voltage Thresholds | VIL ≤ 0.3V, VIH ≥ 3.85V at VCC = 5.5V - provides robust noise margin (>1.5V) in electrically noisy environments. |
| Three-State Leakage Current | ±10μA max at -55°C to +125°C - minimizes standby power and prevents unintended loading of shared buses. |
| ESD Protection | 2kV per MIL-STD-883 Method 3015 - meets industrial handling requirements without additional protection circuitry. |
| Operating Temperature | -55°C to +125°C - qualified for extended-range automotive, aerospace, and downhole instrumentation use. |
Pinout & Package
CD74AC251MG4 is housed in a 16-pin SOIC (D package) with 9.9mm × 6mm footprint and 9.9mm × 3.9mm body size. Pin 1 is located in Quadrant Q1 per tape-and-reel orientation standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (I3) | Data Input | Third of eight selectable data sources; routed to Y/Y̅ when S2S1S0 = 011. |
| 7 (OE) | Active-Low Enable | Drives both outputs into high-Z when HIGH; enables routing only when LOW. |
| 5 (Y) | True Output | Active-high mirror of selected input; complements Y̅ for differential sensing or bus arbitration. |
| 6 (Y̅) | Inverted Output | Complementary signal to Y; eliminates need for external inverters in parity or enable logic. |
| 9–11 (S2, S1, S0) | Address Select Inputs | Binary-coded 3-bit select bus determining I0–I7 routing; fully buffered for low capacitive loading. |
| 16 (VCC) | Positive Supply | Primary power rail; requires local 0.1μF bypass capacitor to suppress switching noise on shared rails. |
| 8 (GND) | Ground Reference | Signal and power return path; must be low-impedance connection to minimize ground bounce. |
Key Features
| Feature | Design Value |
|---|---|
| 1.5V–5.5V Wide-Voltage Operation | Enables single-device compatibility across legacy 5V, modern 3.3V, and emerging 1.8V subsystems without redesign. |
| Balanced Propagation Delays | Minimizes skew between data and select paths (<1.5ns mismatch), critical for glitch-free bus arbitration. |
| ±24mA Output Drive | Eliminates need for external line drivers in point-to-point or short-bus configurations up to 15 loads. |
| SCR-Latchup Resistant Process | Prevents destructive latch-up under transient overvoltage or ESD events, enhancing field reliability. |
| Buffered Inputs | Reduces input capacitance to 10pF and isolates internal logic from PCB trace impedance variations. |
Applications
| Industrial PLC I/O Expansion | Automotive Sensor Multiplexing |
|---|---|
|
Use Scenario: A programmable logic controller routes analog sensor readings from 8 temperature probes to a single ADC channel via time-division sampling. IC Role / Device Role / Timing Role: Data selector synchronizing probe access with microcontroller clock edges; OE controlled by timer interrupt. Use Value: Reduces BOM cost and board area by replacing eight individual analog switches with one CD74AC251MG4 and minimal support passives. |
Use Scenario: An engine control unit consolidates signals from crankshaft, camshaft, knock, and oxygen sensors onto a shared diagnostic bus. IC Role / Device Role / Timing Role: High-speed signal router enabling sequential sensor readout without crosstalk; operates reliably at 125°C ambient. Use Value: Leverages ±24mA drive and 2kV ESD rating to withstand automotive electrical transients without protection diodes. |
| Test Equipment Signal Routing | Legacy System Bus Interface |
|
Use Scenario: Automated test equipment selects one of eight DUT signals for oscilloscope capture while maintaining signal integrity. IC Role / Device Role / Timing Role: Low-skew multiplexer ensuring sub-15ns timing alignment between trigger and sampled waveform. Use Value: Balanced tPLH/tPHL and 12.3ns max delay guarantee deterministic acquisition window across all channels. |
Use Scenario: Retrofitting a 16-bit ISA bus card with modern microcontroller logic requiring 8-bit data path selection. IC Role / Device Role / Timing Role: Level-translating data switch bridging 5V ISA address/data lines to 3.3V FPGA I/O banks. Use Value: 1.5V–5.5V operation allows direct connection without level-shifter ICs, simplifying layout and reducing latency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-input multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AC251N | Dual-in-line (PDIP-16) package; identical AC logic family, same pinout, but larger footprint and no surface-mount reflow compatibility. | Suitable for prototyping or through-hole production; lacks SOIC thermal performance (RθJA = 119.9°C/W vs. PDIP's ~70°C/W). | Select when hand-soldering or breadboarding is required; avoid for high-density or thermally constrained designs. |
| CD74HC251M96 | HC logic family: lower drive (±4mA), slower speed (24ns typ), narrower VCC range (2V–6V), but lower quiescent current (4μA vs. 160μA). | Better for ultra-low-power battery-operated systems where speed <10MHz suffices and drive >±4mA is not needed. | Choose HC variant only if power budget is tighter than timing or drive requirements; not drop-in compatible due to parameter shifts. |
Compared with SN74AC251N and CD74HC251M96, the CD74AC251MG4 uniquely balances high-speed operation, industrial-grade drive strength, and wide-voltage flexibility in a compact SOIC package - making it optimal for space-constrained, mixed-voltage embedded systems demanding deterministic timing and ruggedness.
Availability
CD74AC251MG4 is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, automotive sensor multiplexing, automated test equipment signal routing, and legacy system bus interface requiring stable component supply across extended temperature ranges.
Supply support for CD74AC251MG4 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 connectivity technologies, with over 90 years of innovation in high-reliability components.
The CD74AC251MG4 belongs to TI's Advanced CMOS Logic (AC) product line, engineered for high-speed, low-power digital signal routing in industrial, automotive, and test equipment where timing precision and voltage flexibility are critical.
FAQ
What is the maximum operating temperature range for CD74AC251MG4?
The CD74AC251MG4 is rated for operation from -55°C to +125°C, meeting extended industrial and automotive under-hood requirements. This range is validated per TI's recommended operating conditions and thermal metrics (RθJA = 119.9°C/W), ensuring reliable functionality without derating in harsh thermal environments where the CD74AC251MG4 is deployed.
Does CD74AC251MG4 support 3.3V-only logic systems?
Yes, CD74AC251MG4 operates fully within 1.5V–5.5V supply range, including nominal 3.3V systems. At VCC = 3.3V, it delivers 4.7ns typical propagation delay and maintains VIH/VIL thresholds that provide >1V noise margin - confirming robust interoperability with 3.3V microcontrollers and FPGAs without level translation.
Can CD74AC251MG4 drive a 50Ω transmission line directly?
Yes, CD74AC251MG4 is specified to drive 50Ω transmission lines at 85°C with 75mA sink/source current (per TI's footnote 2), verified by test condition -75mA at 5.5V. Its ±24mA output drive at 5V supports clean edge rates on short traces, and the CD74AC251MG4's low output capacitance (15pF) preserves signal integrity without termination resistors in point-to-point layouts.
What is the function of the Y̅ (complement) output on CD74AC251MG4?
The Y̅ output on CD74AC251MG4 provides the logical inverse of the Y output, enabling direct implementation of differential signaling, parity generation, or active-low enable logic without external inverters. When I3 is selected and OE is low, Y = I3 and Y̅ = I3̅ simultaneously - a feature leveraged in bus arbitration and fault-tolerant interface designs using the CD74AC251MG4.
Is CD74AC251MG4 pin-compatible with CD74ACT251?
No, CD74AC251MG4 is not pin-compatible with CD74ACT251. Although both are 16-pin SOIC 8:1 multiplexers, the ACT version uses different input thresholds and higher drive (±24mA vs. ±50mA), and TI explicitly removed ACT references from the CD74AC251MG4 datasheet revision history - indicating distinct qualification, timing, and drive characteristics that preclude direct substitution without validation.
CD74AC251MG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Type:
- Multiplexer
- Circuit:
- 1 x 8:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- 75mA, 75mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 1.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
CD74AC251MG4 FAQ
1.How can I place an order for CD74AC251MG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74AC251MG4 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 CD74AC251MG4 reliable?
The price and inventory of CD74AC251MG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74AC251MG4 is usually 5 days.
3.What payment methods are accepted for CD74AC251MG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74AC251MG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74AC251MG4?
CD74AC251MG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74AC251MG4 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 CD74AC251MG4?
For technical support, including CD74AC251MG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74AC251MG4 requirements.
6.How does Aetrix verify that CD74AC251MG4 is sourced from the original manufacturer or authorized distributors?
All CD74AC251MG4 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 CD74AC251MG4 meets industry standards.
7.What is the process for return or replacement of CD74AC251MG4?
All CD74AC251MG4 units undergo pre-shipment inspection (PSI). If there is an issue with CD74AC251MG4, 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 CD74AC251MG4 part is unused and in its original packaging.
Return procedure for CD74AC251MG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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