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Texas Instruments SN74CBT3126DR
- Part No.:
- SN74CBT3126DR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74CBT3126DR.pdf
- Description:
- IC BUS SWITCH 1 X 1:1 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,415
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Product details
Overview
SN74CBT3126DR from Texas Instruments is a quadruple FET bus switch IC used for high-speed, low-distortion signal routing in digital data paths. It features four independent 5-Ω bidirectional switches, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and operates from 4 V to 5.5 V supply. Each switch disconnects when its OE input is low, enabling precise bus isolation in memory expansion and address/data multiplexing applications.
For engineers reviewing the SN74CBT3126DR datasheet, SN74CBT3126DR pinout, SN74CBT3126DR application, or SN74CBT3126DR equivalent, key selection criteria include on-state resistance (5–7 Ω), propagation delay (0.25–0.35 ns at 5 V), latch-up immunity (>250 mA per JESD 17), thermal performance (θJA = 86°C/W in SOIC-D), and compatibility with 3.3 V/5 V mixed-signal systems.
Technical Context
This device implements four independent NMOS transmission-gate bus switches with no internal logic inversion-signal path A ↔ B is fully bidirectional and transparent when OE is high. The FET architecture eliminates DC path current during switching and supports rail-to-rail analog/digital signal pass-through without level-shifting.
Each channel's enable logic is asynchronous and non-latched; output-enable (OE) directly controls switch conduction state with no internal timing dependencies. The design ensures high-impedance isolation during power-up/down when OE is pulled low via external pulldown resistor, satisfying system-level reset sequencing requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| On-state resistance (ron) | 5–7 Ω at VCC = 4.5 V, II = 30 mA - enables low-loss signal coupling with <10 mV drop at 30 mA, critical for integrity in high-speed parallel buses. |
| Propagation delay (tpd) | 0.25 ns (VCC = 5 V) - supports >3 GHz effective toggle rates, suitable for fast address/data strobing in microprocessor peripheral interfaces. |
| Supply voltage range | 4 V to 5.5 V - compatible with standard 5 V TTL and mixed 3.3 V/5 V I/O domains when VCC = 5 V. |
| Input voltage thresholds | VIH = 2 V, VIL = 0.8 V - ensures reliable recognition of TTL logic levels across temperature (−40°C to 85°C). |
| Latch-up immunity | >250 mA per JESD 17 - guarantees robustness against transient current faults in hot-plug or bus contention scenarios. |
| Off-state capacitance (Cio) | 4 pF - minimizes capacitive loading on driven lines, preserving signal edge rate in high-frequency data paths. |
Pinout & Package
SN74CBT3126DR uses the SOIC-14 (D) package: 8.75 mm × 3.91 mm body, 1.75 mm max height, 1.27 mm lead pitch, gull-wing leads. Pin 1 marked by beveled corner or index notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE, 3OE, 4OE | Channel enable inputs | Active-high logic control: OE = high connects A↔B; OE = low forces high-Z isolation per channel. |
| 1A–4A, 1B–4B | Bidirectional signal terminals | Passive FET switch ports-no directionality; voltage and current flow freely in either direction when enabled. |
| VCC | Power supply | Single 4–5.5 V supply powers all four switches and control circuitry; no separate logic or analog rail required. |
| GND | Ground reference | Common return for supply and all I/O; must be low-inductance connection to maintain noise margin and switching integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Low on-resistance | 5–7 Ω typical - reduces voltage drop and power loss in high-current data lines (e.g., 32-bit address buses). |
| TTL-compatible control | VIH = 2 V, VIL = 0.8 V - eliminates need for level shifters when interfacing with legacy 5 V microcontrollers or FPGAs. |
| Fast switching | tpd = 0.25 ns, ten/tdis = 1.6/1.0 ns - supports sub-nanosecond timing budgets in DDR memory buffers and test equipment signal routing. |
| High-impedance fail-safe | OE tied to GND via pulldown ensures default isolation at power-up - prevents bus contention before system initialization completes. |
| Latch-up hardened | Exceeds 250 mA per JESD 17 - withstands ESD-induced transients and accidental shorts without destructive latch-up. |
Applications
| Memory Expansion Interface | Microcontroller Peripheral Multiplexing |
|---|---|
Use Scenario: Adding external SRAM or Flash to an MCU with limited address/data pins by time-multiplexing shared bus lines. IC Role / Device Role / Timing Role: SN74CBT3126DR acts as a bidirectional bus gate, isolating memory segments during access cycles and preventing signal contention. Use Value: Enables clean separation of address/data phases with <0.35 ns delay and 5 Ω Ron, preserving setup/hold timing margins in 20+ MHz bus systems. |
Use Scenario: Sharing GPIO pins between UART, SPI, and I²C peripherals on resource-constrained microcontrollers. IC Role / Device Role / Timing Role: SN74CBT3126DR routes signals selectively under firmware control, acting as a reconfigurable I/O switch matrix. Use Value: Eliminates need for discrete MOSFETs or complex PCB routing; TTL-compatible OE inputs simplify direct MCU GPIO drive without level translation. |
| Test Equipment Signal Routing | Digital Logic Level Translation |
Use Scenario: Automated test fixtures requiring dynamic reconfiguration of stimulus/response paths between DUT and instrumentation. IC Role / Device Role / Timing Role: SN74CBT3126DR serves as a low-capacitance (<4 pF), low-Ron signal path selector in high-fidelity digital pattern generators. Use Value: Maintains signal integrity up to 1 GHz due to minimal RC distortion; 0.25 ns tpd allows precise timing alignment in synchronized multi-channel test setups. |
Use Scenario: Interfacing 3.3 V FPGA I/O banks with 5 V legacy peripherals while maintaining bidirectional data flow. IC Role / Device Role / Timing Role: SN74CBT3126DR functions as a passive voltage-tolerant bridge-no level-shifting circuitry needed since it passes voltages within its 0–5.5 V range. Use Value: Supports rail-to-rail analog/digital signal pass-through (e.g., I²C SDA/SCL) without added propagation delay or power consumption of active translators. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FET bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384DR | 8-channel, higher Ron (7–9 Ω), supports 3.3 V only (VCC = 2.3–3.6 V) | Designed for low-voltage LVTTL/LVCMOS systems; not 5 V tolerant | Select when operating exclusively at 3.3 V and higher channel count is required. |
| 74LVC1G3157DBVR | Single-channel, lower Ron (3–5 Ω), smaller X2SON-6 package, VCC = 1.65–5.5 V | Optimized for space-constrained single-line switching; lacks quad integration | Choose for point-of-load signal gating where board area is critical and channel count is low. |
Compared with SN74CBT3126DR, SN74CBTD3384DR offers double the channel density but sacrifices 5 V operation and adds ~2 Ω Ron, while 74LVC1G3157DBVR delivers lower resistance and wider voltage range in a tiny footprint-but requires four separate devices to match quad functionality and increases layout complexity.
Availability
SN74CBT3126DR is available at Aetrix Electronics and suitable for memory expansion interfaces, microcontroller peripheral multiplexing, test equipment signal routing, and digital logic level translation requiring stable component supply and long-term industrial availability.
Supply support for SN74CBT3126DR 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 high-reliability interface solutions.
The SN74CBT3126DR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for ultra-low-delay, low-Ron signal routing in high-speed digital systems such as computing, communications, and industrial control.
FAQ
What is the maximum continuous current rating per channel of the SN74CBT3126DR?
The SN74CBT3126DR supports a continuous channel current of 128 mA per switch. This rating is defined under absolute maximum conditions and ensures safe operation with adequate PCB copper pour and thermal relief. For sustained 100 mA loads, derating per JEDEC guidelines is recommended to maintain junction temperature below 125°C in SOIC-D packaging.
Does the SN74CBT3126DR require external pull-up or pull-down resistors on its OE inputs?
Yes-the SN74CBT3126DR OE inputs must be actively driven or pulled to a defined logic state. To ensure high-impedance isolation during power-up/down, TI recommends tying each OE to GND through a pulldown resistor; minimum value depends on driver sink capability but typically ranges from 1 kΩ to 10 kΩ for robust noise immunity and fast disable timing.
Can the SN74CBT3126DR be used to switch analog signals such as audio or sensor outputs?
Yes-the SN74CBT3126DR is a passive FET switch with rail-to-rail analog capability. It passes signals from 0 V to VCC (up to 5.5 V) with minimal distortion, making it suitable for low-frequency analog routing (e.g., audio line switching, thermistor multiplexing) provided signal swing remains within the device's voltage ratings and bandwidth limitations (~1 GHz small-signal cutoff).
What is the thermal resistance (θJA) of the SN74CBT3126DR in its SOIC-14 package?
The SN74CBT3126DR in SOIC-14 (D) package has a specified junction-to-ambient thermal resistance (θJA) of 86°C/W under standard JEDEC test conditions (2-layer board, 1 in² copper). Actual thermal performance improves significantly with added copper pour, thermal vias, or heatsinking-critical for designs operating near maximum current limits.
Is the SN74CBT3126DR pin-compatible with other members of the '126 bus switch family?
Yes-the SN74CBT3126DR uses the industry-standard '126-type pinout common to SOIC-14, SSOP-14, TSSOP-14, and VQFN-14 variants (e.g., SN74CBT3126PWR, SN74CBT3126RGYR). All share identical pin assignments for VCC, GND, OE, A, and B terminals, enabling drop-in replacement across packages when mechanical and thermal constraints allow.
SN74CBT3126DR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Bus Switch
- Circuit:
- 1 x 1:1
- Independent Circuits:
- 4
- 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:
- 14-SOIC
SN74CBT3126DR FAQ
1.How can I place an order for SN74CBT3126DR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3126DR 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 SN74CBT3126DR reliable?
The price and inventory of SN74CBT3126DR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3126DR is usually 5 days.
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SN74CBT3126DR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3126DR 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 SN74CBT3126DR?
For technical support, including SN74CBT3126DR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3126DR requirements.
6.How does Aetrix verify that SN74CBT3126DR is sourced from the original manufacturer or authorized distributors?
All SN74CBT3126DR 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 SN74CBT3126DR meets industry standards.
7.What is the process for return or replacement of SN74CBT3126DR?
All SN74CBT3126DR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3126DR, 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 SN74CBT3126DR part is unused and in its original packaging.
Return procedure for SN74CBT3126DR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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