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Texas Instruments SN74CBT3257CDBQR
- Part No.:
- SN74CBT3257CDBQR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
SN74CBT3257CDBQR.pdf
- Description:
- IC MUX/DEMUX 4 X 2:1 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,857
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Product details
Overview
SN74CBT3257CDBQR from Texas Instruments is a 4-bit 1-of-2 FET multiplexer/demultiplexer with bidirectional signal routing, 3 Ω typical ON-state resistance, near-zero propagation delay (0.15 ns at 5 V), and undershoot protection to −2 V on A/B ports. It operates from 4 V to 5.5 V and supports mixed-voltage I/O (0–5 V), enabling USB interface isolation and bus gating in industrial control systems.
For engineers reviewing the SN74CBT3257CDBQR datasheet, SN74CBT3257CDBQR pinout, SN74CBT3257CDBQR application, or SN74CBT3257CDBQR equivalent, key selection criteria include its Ioff partial-power-down capability, 5.5 pF typical OFF-state B-port capacitance, TTL/CMOS-compatible control inputs, and SSOP-16 (DBQ) package compatibility with high-density PCB layouts.
Technical Context
The SN74CBT3257CDBQR implements four independent analog/digital SPDT switches controlled by a shared select (S) input and global output-enable (OE) signal. Each switch uses low-threshold FETs with active undershoot-protection circuitry that clamps transient excursions below −2 V while maintaining OFF-state isolation.
Its Ioff specification ensures no backflow current during partial power-down, and the device guarantees high-impedance isolation between A and B ports when OE is high - critical for hot-swap and multi-rail system interoperability without external isolation components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4 V to 5.5 V - compatible with standard 5-V logic rails and tolerant of supply droop in industrial environments. |
| ron (Typ) | 3 Ω - minimizes voltage drop and signal distortion for analog/digital signals up to ±128 mA per channel. |
| Cio(OFF) | 5.5 pF (B port) - reduces capacitive loading on driven buses, preserving signal integrity in high-speed USB or I²C expansion paths. |
| tpd (Max) | 0.24 ns (VCC = 4 V) - enables sub-nanosecond switching for timing-critical data gating without introducing measurable latency. |
| Ioff | 10 µA (VCC = 0 V) - prevents damaging current flow during power sequencing, supporting safe partial-power-down operation. |
| VIKU | −2 V (undershoot clamp) - protects connected devices from negative transients during hot-plug or ESD events on A/B I/O lines. |
| ICC (Max) | 3 µA - ultra-low quiescent current enables use in always-on monitoring circuits without impacting system power budget. |
Pinout & Package
SN74CBT3257CDBQR is housed in a 16-pin SSOP (Shrink Small-Outline Package), DBQ variant, with 0.65 mm lead pitch, 5.9 mm × 4.9 mm body size, and 1.75 mm max height. The package is RoHS-compliant, moisture sensitivity level (MSL) 2, and optimized for automated surface-mount assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 5, 6, 7, 10, 11, 12, 14, 15, 16 | A/B data I/O terminals (1A/1B1/1B2, 2A/2B1/2B2, 3A/3B1/3B2, 4A/4B1/4B2) | Bidirectional signal paths - each pair forms an independently switchable SPDT path; no internal directionality or voltage-level translation. |
| 4 | S (Select) | Controls routing: S = L connects A to B1; S = H connects A to B2 - enables 1-of-2 multiplexing per channel. |
| 8 | GND | Ground reference for all internal circuitry and I/O clamping diodes - must be solidly connected to system ground plane. |
| 13 | VCC | Power supply input - supplies internal bias and switch control; decoupling capacitor (0.1 µF) required adjacent to pin. |
| 9 | OE (Output Enable) | Active-low enable: OE = L enables switching; OE = H forces all channels into high-impedance state - essential for bus arbitration and isolation. |
Key Features
| Feature | Design Value |
|---|---|
| Undershoot protection | Clamps A/B port transients to −2 V, preventing latch-up or damage during hot-insertion or ESD events without external diodes. |
| Bidirectional zero-delay switching | Propagation delay ≤0.24 ns ensures transparent signal pass-through - suitable for clock distribution and high-fidelity analog signal routing. |
| Mixed-voltage I/O support | 0–5 V signaling range allows interfacing between 1.8-V, 2.5-V, 3.3-V, and 5-V subsystems without level shifters. |
| Ioff partial-power-down | Blocks current flow when VCC = 0 V, enabling safe insertion/removal in live backplanes or multi-supply systems. |
| Low OFF-capacitance | 5.5 pF (B port) minimizes crosstalk and loading on shared buses like I²C, preserving rise/fall times and noise margins. |
Applications
| USB Interface Isolation | Industrial Bus Expansion |
|---|---|
Use Scenario: Isolating USB 2.0 D+/D− lines between host controller and peripheral during firmware updates or fault recovery. IC Role / Device Role / Timing Role: Bidirectional analog switch providing galvanic separation while preserving signal integrity and timing compliance. Use Value: Enables hot-swap-safe USB port management without violating USB 2.0 differential impedance or jitter specs due to 3 Ω ron and 5.5 pF Cio(OFF). | Use Scenario: Expanding I²C bus nodes across multiple PCBs in programmable logic controllers with mixed-voltage sensor interfaces. IC Role / Device Role / Timing Role: Signal-gating multiplexer allowing dynamic reconfiguration of I²C address space without hardware changes. Use Value: Supports 0–5 V I/O levels and Ioff isolation, eliminating bus contention during power sequencing and enabling seamless multi-supply I²C topology extension. |
| Low-Distortion Audio Routing | Test Equipment Signal Switching |
Use Scenario: Routing line-level analog audio signals between ADC/DAC channels and amplifier outputs in modular audio analyzers. IC Role / Device Role / Timing Role: Low-ron, low-capacitance analog switch minimizing THD+N and preserving wideband frequency response. Use Value: 3 Ω ron and 16.5 pF Cio(ON) ensure <0.01% signal attenuation and flat response up to 10 MHz - critical for precision audio measurement. | Use Scenario: Automated test fixture switching between DUT signal paths and measurement instruments (oscilloscope, logic analyzer) under microcontroller control. IC Role / Device Role / Timing Role: High-speed, low-leakage multiplexer enabling repeatable, low-noise signal path selection in ATE systems. Use Value: 0.15 ns tpd and ±128 mA channel current rating allow precise timing alignment and robust drive capability for TTL/CMOS test stimuli and responses. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FET multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384CDBQR | 10-channel, dual-supply (2.3–3.6 V), higher ron (5 Ω typ), no undershoot protection | Optimized for low-voltage portable systems only; lacks −2 V clamp and 4–5.5 V compatibility | Select only for battery-powered designs requiring lower VCC; not suitable for 5-V industrial or USB applications. |
| 74LVC1G3157GW,125 | Single-channel, 1.65–5.5 V, ron = 5 Ω typ, Cio(OFF) = 6.5 pF, no Ioff or undershoot protection | Targeted at cost-sensitive, low-pin-count applications; lacks multi-channel integration and robustness features | Use where single-pole switching suffices and system-level protection is handled externally; not drop-in for 4-bit routing needs. |
Compared with SN74CBT3257CDBQR, SN74CBTD3384CDBQR offers more channels but sacrifices undershoot protection and 5-V compatibility, while 74LVC1G3157GW,125 provides broader voltage range but lacks integrated Ioff and multi-bit coordination - making SN74CBT3257CDBQR uniquely suited for robust, 4-channel, 5-V bus isolation.
Availability
SN74CBT3257CDBQR is available at Aetrix Electronics and suitable for USB interface isolation, industrial bus expansion, low-distortion audio routing, and test equipment signal switching requiring stable component supply and long-term production continuity.
Supply support for SN74CBT3257CDBQR 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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, longevity, and industrial-grade performance.
The SN74CBT3257CDBQR belongs to TI's CBT (Crosspoint Bus Transceiver) family, engineered for high-speed, low-distortion signal routing in mixed-voltage digital and analog systems - particularly targeting bus isolation, hot-swap interfaces, and precision instrumentation.
FAQ
What is the maximum signal voltage supported by SN74CBT3257CDBQR?
The SN74CBT3257CDBQR supports data I/O voltages from 0 V to 5.5 V, including all standard logic levels (0.8 V, 1.2 V, 1.5 V, 1.8 V, 2.5 V, 3.3 V, and 5 V). This allows direct interfacing across mixed-voltage domains without external level-shifting circuitry, and the device maintains specified ron and timing performance across this full range when VCC is within 4–5.5 V.
Does SN74CBT3257CDBQR support hot-swap or partial-power-down operation?
Yes, SN74CBT3257CDBQR supports partial-power-down via its Ioff feature: when VCC = 0 V, leakage current is limited to 10 µA maximum, preventing damaging back-current flow through the switch. This enables safe insertion into live backplanes or multi-rail systems - a key requirement for hot-swap-capable infrastructure where SN74CBT3257CDBQR is commonly deployed.
What is the function of the OE pin on SN74CBT3257CDBQR?
The OE (Output Enable) pin on SN74CBT3257CDBQR is an active-low control that globally disables all four switch channels. When OE is high, all A/B paths enter a high-impedance state regardless of S or input states - ensuring complete signal isolation. For reliable power-up behavior, TI recommends tying OE to VCC via a pullup resistor to prevent undefined states during reset sequences.
Can SN74CBT3257CDBQR be used for analog signal routing?
Yes, SN74CBT3257CDBQR is explicitly characterized for both digital and analog applications. Its low 3 Ω typical ON-state resistance, 16.5 pF Cio(ON), and flat frequency response (verified up to 10 MHz) make it suitable for line-level audio, sensor signal multiplexing, and other analog paths where minimal distortion and predictable impedance are required - confirmed in TI's official documentation for SN74CBT3257CDBQR.
What package type is SN74CBT3257CDBQR supplied in, and what are its key mechanical dimensions?
SN74CBT3257CDBQR is supplied in a 16-pin SSOP (Shrink Small-Outline Package), DBQ variant, with 0.65 mm lead pitch, 5.9 mm × 4.9 mm body dimensions, and 1.75 mm maximum height. It features gull-wing leads, MSL Level-2 moisture sensitivity, and is optimized for high-density PCB layouts requiring fine-pitch surface-mount assembly - consistent across all official TI package drawings for SN74CBT3257CDBQR.
SN74CBT3257CDBQR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Multiplexer/Demultiplexer
- Circuit:
- 4 x 2:1
- 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-SSOP
SN74CBT3257CDBQR FAQ
1.How can I place an order for SN74CBT3257CDBQR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3257CDBQR 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 SN74CBT3257CDBQR reliable?
The price and inventory of SN74CBT3257CDBQR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3257CDBQR is usually 5 days.
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SN74CBT3257CDBQR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3257CDBQR 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 SN74CBT3257CDBQR?
For technical support, including SN74CBT3257CDBQR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3257CDBQR requirements.
6.How does Aetrix verify that SN74CBT3257CDBQR is sourced from the original manufacturer or authorized distributors?
All SN74CBT3257CDBQR 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 SN74CBT3257CDBQR meets industry standards.
7.What is the process for return or replacement of SN74CBT3257CDBQR?
All SN74CBT3257CDBQR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3257CDBQR, 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 SN74CBT3257CDBQR part is unused and in its original packaging.
Return procedure for SN74CBT3257CDBQR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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