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Texas Instruments SN74CBT3126DBR
- Part No.:
- SN74CBT3126DBR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 14-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74CBT3126DBR.pdf
- Description:
- IC BUS SWITCH 1 X 1:1 14SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,000
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Product details
Overview
SN74CBT3126DBR from Texas Instruments is a quadruple FET bus switch IC used for bidirectional signal routing in digital logic systems. It features four independent 1-bit switches with 5-Ω on-state resistance, TTL-compatible control inputs, and operates from 4 V to 5.5 V supply. It enables high-speed data isolation in memory address/data buses and peripheral interface applications.
For engineers reviewing the SN74CBT3126DBR datasheet, SN74CBT3126DBR pinout, SN74CBT3126DBR application, or SN74CBT3126DBR equivalent, key selection criteria include on-resistance (5–7 Ω), propagation delay (0.25–0.35 ns), latch-up immunity (>250 mA), thermal impedance (96°C/W), and SSOP-14 package compatibility with legacy '126-type layouts.
Technical Context
This device implements four independent NMOS pass-gate switches controlled by active-high OE inputs. Each switch connects A and B ports bidirectionally when enabled, presenting near-zero insertion loss and minimal signal distortion. The FET architecture eliminates DC path between ports in high-impedance state.
It supports hot-swap and partial-power-down operation via pulldown resistor biasing of OE pins. Input clamp current rating (−50 mA) and absolute max VI/VO (−0.5 V to 7 V) ensure robustness against transient overvoltage during system initialization or fault conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| On-state resistance (ron) | 5–7 Ω at VCC = 4.5 V - ensures minimal voltage drop and signal attenuation across switched paths |
| Propagation delay (tpd) | 0.25–0.35 ns at VCC = 5 V, CL = 50 pF - enables >1 GHz signal bandwidth in high-speed digital interconnects |
| Supply voltage range | 4 V to 5.5 V - compatible with standard 5-V TTL and mixed-voltage logic domains |
| Latch-up immunity | >250 mA per JESD 17 - prevents destructive latch-up during I/O stress or ESD events |
| Input leakage current (II) | ±1 μA at VCC = 5.5 V - minimizes loading on upstream drivers and preserves signal integrity |
| Thermal impedance (θJA) | 96°C/W for DB package - defines maximum power dissipation (≈52 mW at ΔT = 5°C) under natural convection |
| Operating temperature | −40°C to +85°C - qualified for industrial-grade embedded and communications equipment |
Pinout & Package
SN74CBT3126DBR uses a 14-pin SSOP (Shrink Small-Outline Package) with 0.65 mm lead pitch and 2.0 mm max height. Pin 1 index is marked by a beveled corner; leads are gull-wing shaped for surface-mount reflow assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE, 3OE, 4OE | Active-high output-enable control | Drives corresponding switch ON (A↔B connected) when high; forces high-impedance OFF state when low |
| 1A–4A, 1B–4B | Bidirectional signal terminals | Each A/B pair forms a low-resistance, symmetrical signal path; no directionality or voltage polarity restriction |
| VCC | Positive supply | Power rail for internal FET channel biasing; must be decoupled locally to suppress switching noise |
| GND | Ground reference | Common return for all switch channels and control logic; requires low-inductance PCB connection |
Key Features
| Feature | Design Value |
|---|---|
| Standard '126-type pinout | Direct replacement for legacy 74-series bus switches without PCB redesign |
| TTL-compatible input thresholds | VIL ≤ 0.8 V / VIH ≥ 2 V - interoperable with 5-V CMOS and bipolar logic families |
| Low on-capacitance (Cio(OFF)) | 4 pF - reduces crosstalk and maintains signal edge rate in dense routing environments |
| High-speed enable/disable timing | ten = 1.6–5.4 ns, tdis = 1–5 ns - supports cycle-accurate bus arbitration in synchronous systems |
| Robust ESD protection | Exceeds JESD 22-A114 (2 kV HBM) - enhances reliability in handling and board-level integration |
Applications
| Memory Address Multiplexing | Peripheral Bus Isolation |
|---|---|
Use Scenario: Selectively route address lines between CPU and multiple memory banks while preventing contention. IC Role / Device Role / Timing Role: Bidirectional analog switch enabling/disabling address path per bank select signal. Use Value: Eliminates need for tristate buffers or complex glue logic; maintains signal integrity with <0.35 ns delay and 5-Ω Ron. |
Use Scenario: Isolate USB or UART peripherals during system sleep mode to reduce standby current. IC Role / Device Role / Timing Role: Signal gate controlled by power-management unit to disconnect I/O lines before domain shutdown. Use Value: Prevents back-powering of disabled peripherals; supports hot-plug readiness with sub-5 ns enable/disable response. |
| Test Access Port Switching | Logic-Level Translation Interface |
Use Scenario: Share JTAG or SWD debug interface among multiple MCUs on a shared test bus. IC Role / Device Role / Timing Role: Low-latency multiplexer selecting one target MCU's TDI/TDO lines to host debugger. Use Value: Enables single-tester multi-device validation without signal degradation; 4 pF off-capacitance minimizes skew. |
Use Scenario: Interface 3.3-V FPGA I/O to 5-V sensor subsystem while preserving timing margins. IC Role / Device Role / Timing Role: Passive level-shifting element leveraging bidirectional conduction and rail-to-rail voltage tolerance. Use Value: No external bias required; supports 0–5.5 V signal swing on both sides; avoids translation delay of active translators. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384DBR | 8-channel, higher drive strength (128 mA), 3.3-V only supply | Requires 3.3-V domain; not suitable for 5-V mixed-signal systems | Select when higher current capability and lower voltage operation are needed; verify VCC compatibility. |
| 74LVC1G3157DBVR | Single-channel, 1.65–5.5 V operation, smaller SOT-23-6 package | Lower integration density; lacks quad-channel layout efficiency for parallel bus use | Prefer for space-constrained designs needing only one switch; not drop-in for 14-pin SSOP footprint. |
Compared with SN74CBT3126DBR, SN74CBTD3384DBR offers double channel count but sacrifices 5-V compatibility, while 74LVC1G3157DBVR provides wider voltage range in a compact form but requires four discrete placements to match quad functionality-making SN74CBT3126DBR optimal for cost-sensitive, 5-V, space-efficient bus gating.
Availability
SN74CBT3126DBR is available at Aetrix Electronics and suitable for industrial control interfaces, memory expansion modules, and embedded test infrastructure requiring stable component supply and long-term obsolescence management.
Supply support for SN74CBT3126DBR 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 logic solutions with over 50 years of innovation in high-reliability interface ICs.
The SN74CBT3126DBR belongs to TI's CBT (Crossbar Bus Transceiver) logic family, designed specifically for low-latency, low-distortion signal routing in high-speed digital systems where timing predictability and signal fidelity are critical.
FAQ
What is the maximum continuous current rating per channel of the SN74CBT3126DBR?
The SN74CBT3126DBR supports a continuous channel current of 128 mA per switch, as specified in its absolute maximum ratings. This rating applies under steady-state conditions with proper thermal management and ensures reliable conduction without thermal runaway or parametric shift. Exceeding this value may degrade on-resistance stability or accelerate wear-out mechanisms.
Does the SN74CBT3126DBR require external pull-up or pull-down resistors on its OE pins?
Yes - to guarantee high-impedance state during power-up or power-down, each OE pin of the SN74CBT3126DBR must be tied to GND through a pulldown resistor. TI recommends sizing the resistor based on the driving source's current-sourcing capability; typical values range from 1 kΩ to 10 kΩ depending on system noise margin and rise-time requirements.
Can the SN74CBT3126DBR be used for level shifting between 3.3 V and 5 V logic domains?
Yes - the SN74CBT3126DBR supports bidirectional signal translation between 3.3 V and 5 V domains because its FET pass-gate architecture allows voltage swing up to VCC on either side, and its absolute input voltage range extends to −0.5 V to 7 V. However, VCC must be set to the higher rail (5 V) to ensure full conduction and avoid forward-biasing internal protection diodes.
What is the thermal impedance (θJA) of the SN74CBT3126DBR in its SSOP-14 package?
The SN74CBT3126DBR has a junction-to-ambient thermal impedance (θJA) of 96°C/W for the DB package, measured per JESD 51-7 under standard JEDEC PCB mounting conditions. This value assumes a two-layer board with 1 in² copper area per pin; actual performance improves with enhanced copper pour or thermal vias beneath the package body.
Is the SN74CBT3126DBR pin-compatible with older 74LS126 devices?
No - although the SN74CBT3126DBR uses the standard '126-type pinout (matching D, DB, PW, and RGY packages), it is not functionally or electrically pin-compatible with 74LS126. The LS variant is a tri-state buffer with active-low enable and different drive characteristics, whereas SN74CBT3126DBR is a bidirectional FET switch with active-high OE and no internal logic inversion or amplification.
SN74CBT3126DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 14-SSOP (0.209", 5.30mm 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-SSOP
SN74CBT3126DBR FAQ
1.How can I place an order for SN74CBT3126DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3126DBR 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 SN74CBT3126DBR reliable?
The price and inventory of SN74CBT3126DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3126DBR is usually 5 days.
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Once your SN74CBT3126DBR 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 SN74CBT3126DBR?
For technical support, including SN74CBT3126DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3126DBR requirements.
6.How does Aetrix verify that SN74CBT3126DBR is sourced from the original manufacturer or authorized distributors?
All SN74CBT3126DBR 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 SN74CBT3126DBR meets industry standards.
7.What is the process for return or replacement of SN74CBT3126DBR?
All SN74CBT3126DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3126DBR, 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 SN74CBT3126DBR part is unused and in its original packaging.
Return procedure for SN74CBT3126DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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