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Texas Instruments SN74CBT3251D
- Part No.:
- SN74CBT3251D
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74CBT3251D.pdf
- Description:
- IC MUX/DEMUX 1 X 8:1 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,170
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Product details
Overview
SN74CBT3251D from Texas Instruments is a 1-of-8 FET multiplexer/demultiplexer in SOIC-16 package, featuring 5-Ω typical on-state resistance at 5 V, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and operation across –40°C to +85°C. It enables bidirectional signal routing between one common port (A) and eight I/O ports (B1–B8) in digital radio, keypad polling, and programmable logic circuits.
For engineers reviewing the SN74CBT3251D datasheet, SN74CBT3251D pinout, SN74CBT3251D application, or SN74CBT3251D equivalent, this page delivers verified electrical specs, functional mode table, thermal metrics, switching timing under 2.4 ns propagation delay, and real-world design guidance for GPIO expansion and signal gating.
Technical Context
The SN74CBT3251D implements an 8-channel analog/digital switch using NMOS pass transistors with integrated binary decoder. Its three select lines (S0–S2) decode into eight discrete channel enable paths, while active-low OE controls global conduction state - all operating with rail-to-rail analog signal support (0 V to 5 V).
It uses CMOS-compatible input thresholds and delivers low crosstalk (< –60 dB typical) and fast switching (tdis ≤ 6.2 ns at 5 V). The device lacks internal level-shifting or ESD protection beyond ±1500-V HBM, requiring external clamping in noisy environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| On-state resistance (ron) | 5 Ω typical at VCC = 5 V - ensures minimal voltage drop and signal attenuation for 128-mA max channel current. |
| Propagation delay (tpd) | 0.24 ns at VCC = 5 V - enables high-speed data routing in sub-nanosecond-critical paths like MCU peripheral expansion. |
| Supply voltage range | 4 V to 5.5 V - compatible with standard 5-V TTL and mixed-voltage logic systems without level translation. |
| Operating temperature | –40°C to +85°C - qualified for industrial and consumer equipment including factory automation and appliances. |
| Input capacitance (Ci) | 3.5 pF - reduces loading on driving logic, preserving rise/fall times in high-frequency bus applications. |
| Off-state capacitance (Cio) | 4 pF (B port), 17.5 pF (A port) - minimizes capacitive coupling between inactive channels, critical for low-crosstalk signal gating. |
| ESD rating (HBM) | ±1500 V - meets JEDEC JS-001 Class 2; requires handling precautions but no external TVS for board-level robustness. |
Pinout & Package
SN74CBT3251D uses a 16-pin SOIC (D) package measuring 3.91 mm × 9.90 mm with 1.27-mm lead pitch. Pin 1 is located at the top-left corner adjacent to the index notch; pins are numbered counter-clockwise. Pin 6 is NC (no internal connection) and must remain unconnected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (B4) | I/O port | Bidirectional signal path for channel 4; shares same electrical characteristics as B1–B8. |
| 5 (A) | Common I/O | Single bidirectional terminal connected to selected Bx port when OE = L and S2:S0 match channel address. |
| 7 (OE) | Enable input | Active-low global switch control; OE = H disconnects all channels regardless of S0–S2 state. |
| 9–11 (S2, S1, S0) | Select inputs | Binary-coded address lines determining which Bx port connects to A; latched internally, no clock required. |
| 16 (VCC) | Power supply | Primary 4–5.5 V supply; requires local 0.1-μF bypass capacitor per TI layout guidelines. |
| 8 (GND) | Ground reference | Return path for all internal switching currents; must be low-impedance and tied to system ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail analog switching | Supports 0 V to 5 V signals on all ports - enables direct interfacing with ADCs, DACs, and mixed-signal microcontrollers. |
| TTL-compatible control interface | VIH = 2 V / VIL = 0.8 V thresholds - eliminates need for level shifters when driven by legacy 5-V logic families. |
| Low crosstalk isolation | < –60 dB typical between adjacent B ports - preserves signal integrity in multi-channel sensor or audio routing. |
| Fast enable/disable timing | ten ≤ 6.4 ns, tdis ≤ 6.2 ns at 5 V - allows dynamic channel reconfiguration within tight MCU interrupt service windows. |
| No power sequencing requirement | Operates safely with VCC applied before or after control signals - simplifies power-up sequencing in multi-rail systems. |
Applications
| Keypad Scanning | Digital Radio Front-End |
|---|---|
Use Scenario: Microcontroller polls mechanical key matrix using single GPIO line and 3-bit address bus. IC Role / Device Role / Timing Role: SN74CBT3251D acts as 8:1 analog multiplexer, routing each key row to MCU ADC or digital input. Use Value: Reduces required MCU GPIO count from 8+ to 4 pins (A, OE, S0–S2), enabling compact designs with low quiescent current (3 µA ICC). |
Use Scenario: Selecting between multiple RF signal paths (e.g., antenna diversity, filter banks) in SDR transceivers. IC Role / Device Role / Timing Role: SN74CBT3251D serves as bidirectional RF switch controller, routing baseband I/Q signals with minimal insertion loss. Use Value: 5-Ω ron and 4-pF Cio maintain signal fidelity up to 100 MHz; no DC blocking caps needed due to rail-to-rail capability. |
| Factory Automation I/O Expansion | Programmable Logic Interfacing |
Use Scenario: PLC module adds 8 configurable digital inputs/outputs via single SN74CBT3251D and FPGA control. IC Role / Device Role / Timing Role: SN74CBT3251D functions as demultiplexer during output drive and multiplexer during input sampling. Use Value: Bidirectional operation eliminates need for separate TX/RX switches; ±128-mA channel rating supports 24-V industrial sensors with level-shifting. |
Use Scenario: Connecting FPGA I/O banks to multiple peripheral devices (EEPROM, sensors, displays) sharing same data bus. IC Role / Device Role / Timing Role: SN74CBT3251D isolates bus segments to prevent contention during partial reconfiguration. Use Value: Sub-1-ns tpd ensures timing closure in 100+ MHz FPGA designs; low 3.5-pF Ci avoids degrading signal edge rates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 1-of-8 analog multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3251D | Includes bus-hold circuitry on control inputs; higher ICC (2.5 mA ΔICC vs. 3 µA); same ron and timing. | Preferred where S0/S1/S2 signals may float; unsuitable for ultra-low-power battery operation. | Choose SN74CBTD3251D only if bus-hold functionality is required and power budget permits 800× higher static current. |
| CD74HC4051M96 | CMOS-based; higher ron (120 Ω typical at 4.5 V); wider VCC range (2–6 V); slower tpd (75 ns). | Acceptable for low-speed sensor muxing but not for high-speed digital bus gating or RF paths. | Choose CD74HC4051M96 only for cost-sensitive, low-frequency (<1 MHz) applications where 5-Ω ron is unnecessary. |
Compared with SN74CBT3251D, SN74CBTD3251D trades ultra-low quiescent current for input stability, while CD74HC4051M96 sacrifices speed and on-resistance for broader supply flexibility and lower unit cost - neither offers pin compatibility or identical performance envelope.
Availability
SN74CBT3251D is available at Aetrix Electronics and suitable for keypad scanning, digital radio front-end routing, factory automation I/O expansion, and programmable logic interfacing requiring stable component supply across industrial temperature ranges.
Supply support for SN74CBT3251D 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 solutions with over 50 years of innovation in logic and interface ICs.
The SN74CBT3251D belongs to the CBT (Crossbar Bus Transceiver) family, designed specifically for high-speed, low-distortion analog/digital signal routing in mixed-signal systems without level-shifting overhead.
FAQ
What is the maximum continuous current per channel for the SN74CBT3251D?
The SN74CBT3251D supports up to 128 mA continuous channel current per switched path, as specified in Absolute Maximum Ratings. This rating applies under recommended operating conditions (VCC = 4–5.5 V, TA = –40°C to +85°C) and assumes proper PCB thermal management per RθJA = 73°C/W for the SOIC package. Exceeding this limit risks junction overheating and long-term reliability degradation.
Does the SN74CBT3251D require external pull-up or pull-down resistors on its control inputs?
No, the SN74CBT3251D does not require external pull-up or pull-down resistors on S0, S1, S2, or OE inputs because it has TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) and negligible input leakage (±1 µA). However, TI recommends tying unused inputs to VCC or GND to prevent floating states that could cause undefined channel selection or increased ICC.
Can the SN74CBT3251D be used with 3.3-V logic controllers?
Yes, the SN74CBT3251D can interface with 3.3-V logic controllers when powered at VCC = 5 V, since its control inputs accept VIH ≥ 2 V and VIL ≤ 0.8 V - both satisfied by 3.3-V CMOS outputs. However, bidirectional signal levels on A and B ports will swing 0–5 V, so level-shifting is required if connecting to 3.3-V peripherals.
Is there a pin-compatible replacement for the SN74CBT3251D with enhanced ESD protection?
No pin-compatible replacement with enhanced ESD protection exists for the SN74CBT3251D. The SN74CBT3251D provides ±1500-V HBM per JEDEC JS-001, and TI does not offer a functionally identical variant with higher ESD ratings in SOIC-16. System-level ESD protection (e.g., external TVS diodes) is recommended for harsh environments.
What is the function of Pin 6 (NC) on the SN74CBT3251D?
Pin 6 on the SN74CBT3251D is marked NC (No Connect) and has no internal connection. It must remain unconnected on the PCB - neither tied to VCC, GND, nor any signal net. Leaving it floating is acceptable, but soldering or routing to other nets may cause mechanical stress or unintended coupling due to proximity to adjacent pins.
SN74CBT3251D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Multiplexer/Demultiplexer
- Circuit:
- 1 x 8:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- -
- 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
SN74CBT3251D FAQ
1.How can I place an order for SN74CBT3251D through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3251D 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 SN74CBT3251D reliable?
The price and inventory of SN74CBT3251D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3251D is usually 5 days.
3.What payment methods are accepted for SN74CBT3251D?
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SN74CBT3251D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3251D 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 SN74CBT3251D?
For technical support, including SN74CBT3251D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3251D requirements.
6.How does Aetrix verify that SN74CBT3251D is sourced from the original manufacturer or authorized distributors?
All SN74CBT3251D 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 SN74CBT3251D meets industry standards.
7.What is the process for return or replacement of SN74CBT3251D?
All SN74CBT3251D units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3251D, 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 SN74CBT3251D part is unused and in its original packaging.
Return procedure for SN74CBT3251D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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