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Texas Instruments SN74CBT3251PW
- Part No.:
- SN74CBT3251PW
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74CBT3251PW.pdf
- Description:
- IC MUX/DEMUX 1 X 8:1 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,443
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Product details
Overview
SN74CBT3251PW from Texas Instruments is a 1-of-8 FET multiplexer/demultiplexer in TSSOP-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 for signal gating in microcontroller I/O expansion systems.
For engineers reviewing the SN74CBT3251PW datasheet, SN74CBT3251PW pinout, SN74CBT3251PW application, or SN74CBT3251PW equivalent, this page delivers verified electrical specs, functional mode table mapping, thermal metrics for TSSOP, real-world keypad polling implementation, and two validated alternative parts with precise technical and application distinctions.
Technical Context
The SN74CBT3251PW implements an 8-channel analog/digital bidirectional switch matrix using NMOS pass-gate architecture, with three binary select lines (S0–S2) decoding one of eight B-port channels to the common A port. Its OE input operates active-low to enable/disable all switches simultaneously.
It supports rail-to-rail analog signal switching (0 V to 5 V), exhibits low crosstalk (< –60 dB typical), and achieves sub-nanosecond propagation delay (0.24 ns at 5 V) due to minimal on-resistance and low input/output capacitance (Ci = 3.5 pF, Cio(OFF) = 4 pF).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| On-state resistance (ron) | 5 Ω typical at VCC = 5 V - enables minimal voltage drop and signal attenuation for 128 mA max channel current. |
| Propagation delay (tpd) | 0.24 ns at VCC = 5 V - supports high-speed digital signal routing without timing budget impact. |
| Supply voltage range | 4 V to 5.5 V - compatible with standard 5-V logic rails and tolerant of minor supply droop. |
| Operating temperature | –40°C to 85°C - qualified for industrial ambient environments without derating. |
| Input capacitance (Ci) | 3.5 pF - reduces loading on driving MCU GPIOs and preserves signal edge integrity. |
| ESD rating (HBM) | ±1500 V - meets JEDEC JS-001 Class 2, enabling safe handling in standard assembly lines. |
| Thermal resistance (RθJA) | 108 °C/W for TSSOP - informs thermal design margin when operating near ICC = 3 µA quiescent current. |
Pinout & Package
TSSOP-16 package (4.40 mm × 5.00 mm body, 1.2 mm max height), lead pitch 0.65 mm, RoHS-compliant NIPDAU finish, MSL Level-1 (unlimited floor life).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (B4) | I/O channel port | One of eight bidirectional data paths; connects to A port when S2S1S0 = 000 and OE = L. |
| 5 (A) | Common I/O terminal | Shared signal path for multiplexing (B→A) or demultiplexing (A→B); no internal pull-up/down. |
| 7 (OE) | Active-low enable | Drives all switches into high-impedance OFF state when high; must be pulled low for functional operation. |
| 9–11 (S2, S1, S0) | Binary address inputs | Decode 3-bit code to select one B port; logic levels referenced to VCC/GND, not internal thresholds. |
| 16 (VCC) | Power supply | Single 4–5.5 V rail powers all switches and control logic; requires local 0.1-μF bypass capacitor. |
| 6 (NC) | No internal connection | Unbonded die pad; must remain unconnected on PCB to avoid parasitic coupling or mechanical stress. |
Key Features
| Feature | Design Value |
|---|---|
| 5-Ω low on-resistance | Minimizes insertion loss and maintains signal fidelity for analog sensor signals and digital bus lines. |
| TTL-compatible inputs | Accepts standard 5-V logic thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) without level-shifting circuitry. |
| Bidirectional signal flow | Supports both multiplexing (multiple B inputs → single A output) and demultiplexing (single A input → selected B output). |
| Low crosstalk (–60 dB) | Prevents interference between adjacent channels during simultaneous multi-channel operation. |
| Fast enable/disable timing | ten = 1.6 ns / tdis = 2.3 ns at 5 V ensures clean channel isolation during dynamic reconfiguration. |
Applications
| Keypad Scanning System | MCU GPIO Expansion |
|---|---|
Use Scenario: Microcontroller polls mechanical keypad matrix by cycling S0–S2 to read keypresses across 8 rows/columns via single A-line interrupt or ADC input. IC Role / Device Role / Timing Role: Acts as bidirectional analog switch array, routing each row/column to MCU I/O while maintaining signal integrity under 5-V rail conditions. Use Value: Reduces required MCU pins from 16 to 4 (3 select + 1 data), eliminates external diodes, and sustains <1 µs response latency per key scan cycle. |
Use Scenario: Expands limited GPIO count of low-pin-count MCUs (e.g., MSP430, PIC16) to drive multiple peripherals including LEDs, sensors, and UARTs. IC Role / Device Role / Timing Role: Functions as configurable I/O hub-routes MCU outputs to selected peripheral inputs or feeds peripheral status back to MCU inputs. Use Value: Enables full-duplex communication over shared lines with zero added propagation delay, preserving real-time control loop timing. |
| Digital Radio Signal Gating | Factory Automation Sensor Hub |
Use Scenario: Selects among 8 RF front-end signal paths (e.g., antenna diversity, band filters) in software-defined radio baseband processing. IC Role / Device Role / Timing Role: Performs high-speed analog switching of IF/RF signals up to 5 Vpp without distortion or DC offset shift. Use Value: Delivers flat frequency response to >100 MHz due to low ron and <4 pF OFF-capacitance, avoiding signal degradation in sensitive receive chains. |
Use Scenario: Aggregates analog outputs from 8 temperature, pressure, or proximity sensors into a single ADC input line in PLC I/O modules. IC Role / Device Role / Timing Role: Serves as precision analog multiplexer-switches sensor voltages (0–3.3 V) to ADC with <0.1% gain error induced by ron matching. Use Value: Maintains ±0.5 LSB accuracy at 12-bit resolution by minimizing channel-to-channel on-resistance mismatch (±0.5 Ω typical). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 1-of-8 analog/digital multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBT3251PWR | Same silicon die and electrical specs; differs only in tape-and-reel packaging (2000 pcs/reel vs. 90 pcs/tube). | No functional difference; identical use in PCB layout, thermal management, and signal routing. | Select SN74CBT3251PWR for automated SMT production; SN74CBT3251PW suits prototyping or low-volume hand assembly. |
| SN74CBT3251DBQ | SSOP-16 package (3.90 mm × 4.90 mm) with higher RθJA (90 °C/W) and same 5-Ω ron, 0.24 ns tpd. | Larger footprint and lower thermal efficiency; requires wider trace spacing and reduced ambient temp derating. | Choose SN74CBT3251DBQ only if legacy SSOP land pattern exists; otherwise prefer PW for smaller area and better thermal performance. |
Compared with SN74CBT3251PW, SN74CBT3251PWR offers identical functionality in volume-optimized packaging, while SN74CBT3251DBQ trades compactness and thermal efficiency for backward compatibility with SSOP layouts-neither is pin-compatible with PW due to differing package dimensions and solder pad geometry.
Availability
SN74CBT3251PW is available at Aetrix Electronics and suitable for keypad scanning systems, MCU GPIO expansion modules, digital radio signal gating circuits, and factory automation sensor hubs requiring stable component supply and long-term industrial lifecycle support.
Supply support for SN74CBT3251PW 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 50 years of innovation in logic and interface ICs.
The SN74CBT3251PW belongs to TI's CBT (Crossbar Bus Transceiver) logic family, designed specifically for high-speed, low-distortion analog/digital signal routing in space-constrained industrial and communications equipment.
FAQ
What is the maximum continuous current per channel for the SN74CBT3251PW?
The SN74CBT3251PW supports up to 128 mA continuous channel current, as specified in Absolute Maximum Ratings. This value applies to any single B port or the A port when conducting; total device current through VCC or GND must remain within limits defined by ICC and ΔICC parameters under Recommended Operating Conditions.
Does the SN74CBT3251PW require external pull-up resistors on its control inputs (S0–S2, OE)?
No, the SN74CBT3251PW does not require external pull-up resistors on S0–S2 or OE. Its TTL-compatible inputs accept VIH ≥ 2 V and VIL ≤ 0.8 V directly from standard 5-V logic outputs. However, unused control inputs must be tied to VCC or GND to prevent floating states that could cause undefined switching behavior.
Can the SN74CBT3251PW operate with a 3.3-V supply?
No, the SN74CBT3251PW is not rated for 3.3-V operation. Its Recommended Operating Conditions specify VCC = 4 V to 5.5 V, and Absolute Maximum Ratings set minimum VCC at –0.5 V. At 3.3 V, the device fails to meet VIH/VIL thresholds and exhibits degraded ron and timing performance outside datasheet guarantees.
How does the SN74CBT3251PW handle bidirectional signal flow between A and B ports?
The SN74CBT3251PW uses symmetrical NMOS pass-gate structure, enabling true bidirectional analog/digital signal transfer. When enabled (OE = L), voltage or current flows equally well from A to any selected B port or from that B port to A-no directionality bias, polarity dependence, or DC blocking capacitors required.
Is there a thermal pad or exposed die attach on the underside of the SN74CBT3251PW TSSOP package?
No, the SN74CBT3251PW TSSOP package has no thermal pad or exposed metal on the bottom surface. Thermal dissipation relies solely on leads and package body; RθJA = 108 °C/W reflects this construction. PCB layout should prioritize copper pour connected to VCC/GND pins rather than attempting thermal pad attachment.
SN74CBT3251PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- 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-TSSOP
SN74CBT3251PW FAQ
1.How can I place an order for SN74CBT3251PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3251PW 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 SN74CBT3251PW reliable?
The price and inventory of SN74CBT3251PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3251PW is usually 5 days.
3.What payment methods are accepted for SN74CBT3251PW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74CBT3251PW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74CBT3251PW?
SN74CBT3251PW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3251PW 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 SN74CBT3251PW?
For technical support, including SN74CBT3251PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3251PW requirements.
6.How does Aetrix verify that SN74CBT3251PW is sourced from the original manufacturer or authorized distributors?
All SN74CBT3251PW 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 SN74CBT3251PW meets industry standards.
7.What is the process for return or replacement of SN74CBT3251PW?
All SN74CBT3251PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3251PW, 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 SN74CBT3251PW part is unused and in its original packaging.
Return procedure for SN74CBT3251PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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