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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Texas Instruments SN74CBT3125CPWRG4

Name: SN74CBT3125CPWRG4
Brand: Texas Instruments
SKU: SN74CBT3125CPWRG4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74CBT3125CPWRG4

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 14-TSSOP (0.173", 4.40mm Width)

Datasheet:: SN74CBT3125CPWRG4.pdf

Description:: IC BUS SWITCH 1 X 1:1 14TSSOP

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Product details

Overview

SN74CBT3125CPWRG4 from Texas Instruments is a quadruple FET bus switch IC with independent 5-Ω analog switches, TTL-compatible control inputs, and 4.0–5.5 V supply operation. It enables bidirectional signal routing in data buses, memory expansion interfaces, and level-shifting applications where low on-resistance and fast switching are critical.

For engineers reviewing the SN74CBT3125CPWRG4 datasheet, SN74CBT3125CPWRG4 pinout, SN74CBT3125CPWRG4 application, or SN74CBT3125CPWRG4 equivalent, key selection criteria include on-state resistance (5–7 Ω), propagation delay (0.25–0.35 ns), enable/disable timing (1–6 ns), thermal performance (θ_JA = 113°C/W), and TSSOP-14 package compatibility with high-density PCB layouts.

Technical Context

This device implements four independent single-pole single-throw (SPST) analog switches using NMOS FETs, each controlled by a dedicated output-enable (OE) input. Switch conduction occurs only when OE is logic low (≤0.8 V), establishing a low-impedance path between A and B ports.

The architecture supports bidirectional signal flow with no internal directionality, operates across 4.0–5.5 V V_CC, and maintains high-impedance isolation when OE is high (≥2 V). Input clamp current rating (−50 mA) and absolute maximum VI of −0.5 to 7 V support robust I/O protection during hot-swap or power sequencing events.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Range	4.0 V to 5.5 V - Ensures compatibility with 5-V TTL and mixed-voltage systems without level shifters.
r_ON	5 Ω to 7 Ω - Enables minimal voltage drop (<320 mV at 64 mA) and preserves signal integrity in high-speed digital buses.
t_pd	0.25 ns (V_CC = 5 V) - Supports >1 GHz signal bandwidth for PCIe Gen1, USB 1.1, and legacy parallel bus applications.
t_en/t_dis	1.6 ns / 1.0 ns (V_CC = 5 V) - Allows precise timing control for dynamic bus gating in microcontroller peripheral expansion.
I_CC	3 μA - Ultra-low quiescent current reduces system-level power budget impact in always-on subsystems.
C_io(OFF)	4 pF - Limits capacitive loading on driven lines, preserving rise/fall times in 50-pF load environments.
θ_JA	113°C/W (PW package) - Defines thermal derating limit for continuous 128 mA channel current in standard FR-4 PCBs.

Pinout & Package

TSSOP-14 (PW) package: 4.4 mm × 5.0 mm body, 0.65 mm pitch, 1.2 mm max height, exposed pad not present. Pin 1 index located at top-left corner with beveled edge marking.

Pin/Terminal	Circuit Role	Design Meaning
1, 4, 7, 10	OE_n (Output Enable)	Active-low control per switch; tie to V_CC via pullup resistor to ensure high-Z at power-up.
2, 5, 8, 11	A_n (Port A)	Input/output terminal for first side of bidirectional switch; electrically identical to B_n.
3, 6, 9, 12	B_n (Port B)	Input/output terminal for second side of bidirectional switch; no polarity or direction constraint.
13	V_CC	Positive supply rail; bypass with 0.1 μF ceramic capacitor near pin for noise suppression.
14	GND	Ground reference for all switches and control logic; connect to low-impedance PCB ground plane.

Key Features

Feature	Design Value
5-Ω on-state resistance	Minimizes insertion loss and signal distortion in 50-Ω impedance-matched data paths.
TTL-compatible control inputs	Accepts standard 5-V logic thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2 V) without external biasing.
Independent per-channel enable	Enables selective bus segmentation-e.g., isolate memory banks while keeping peripherals active.
0.25-ns propagation delay	Preserves timing margins in 100-MHz+ parallel address/data buses with tight setup/hold windows.
−0.5 V to 7 V input voltage range	Supports fault-tolerant operation during brownout, hot-insertion, or mixed-supply interface scenarios.

Applications

Memory Expansion Interface	Microcontroller Peripheral Multiplexing
Use Scenario: Adding external SRAM or Flash to an MCU with limited address/data pins by time-division multiplexing shared bus lines. IC Role / Device Role / Timing Role: Bidirectional bus switch isolating memory segments during access; enables concurrent peripheral operation on same bus. Use Value: Eliminates need for complex glue logic or additional address decoders while maintaining full 5-V signal swing and <0.35 ns delay.	Use Scenario: Sharing UART, SPI, or GPIO lines among multiple sensors or actuators on a compact industrial controller PCB. IC Role / Device Role / Timing Role: Channel-selectable signal gate that routes one peripheral's signals to the MCU at a time under firmware control. Use Value: Reduces pin count pressure by 4× versus direct connection; 5-Ω r_ON prevents signal degradation across 10-cm traces.
Legacy Parallel Bus Isolation	Level-Shifted Data Path Gating
Use Scenario: Isolating printer port (LPT), IDE, or ISA bus segments to prevent contention during hot-plug or diagnostic mode. IC Role / Device Role / Timing Role: High-speed analog switch inserted between host controller and peripheral; enabled only during active transfer cycles. Use Value: Prevents back-driving and latch-up during bus arbitration; 4 pF C_io(OFF) avoids signal reflection on unterminated stubs.	Use Scenario: Gating signals between 5-V microcontrollers and 3.3-V FPGA I/O banks without level translators. IC Role / Device Role / Timing Role: Passive bidirectional switch placed between mismatched voltage domains; relies on I/O clamp diodes for protection. Use Value: Enables safe 5-V-to-3.3-V interfacing with <100 mV forward drop across internal FETs; no static current draw in pass-through state.

Memory Expansion Interface

Microcontroller Peripheral Multiplexing

Use Scenario: Adding external SRAM or Flash to an MCU with limited address/data pins by time-division multiplexing shared bus lines.

IC Role / Device Role / Timing Role: Bidirectional bus switch isolating memory segments during access; enables concurrent peripheral operation on same bus.

Use Value: Eliminates need for complex glue logic or additional address decoders while maintaining full 5-V signal swing and <0.35 ns delay.

Use Scenario: Sharing UART, SPI, or GPIO lines among multiple sensors or actuators on a compact industrial controller PCB.

IC Role / Device Role / Timing Role: Channel-selectable signal gate that routes one peripheral's signals to the MCU at a time under firmware control.

Use Value: Reduces pin count pressure by 4× versus direct connection; 5-Ω r_ON prevents signal degradation across 10-cm traces.

Legacy Parallel Bus Isolation

Level-Shifted Data Path Gating

Use Scenario: Isolating printer port (LPT), IDE, or ISA bus segments to prevent contention during hot-plug or diagnostic mode.

IC Role / Device Role / Timing Role: High-speed analog switch inserted between host controller and peripheral; enabled only during active transfer cycles.

Use Value: Prevents back-driving and latch-up during bus arbitration; 4 pF C_io(OFF) avoids signal reflection on unterminated stubs.

Use Scenario: Gating signals between 5-V microcontrollers and 3.3-V FPGA I/O banks without level translators.

IC Role / Device Role / Timing Role: Passive bidirectional switch placed between mismatched voltage domains; relies on I/O clamp diodes for protection.

Use Value: Enables safe 5-V-to-3.3-V interfacing with <100 mV forward drop across internal FETs; no static current draw in pass-through state.

Equivalent & Alternatives

The following parts are listed as comparable options for similar FET bus switch applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74CBTD3384PWR	10-channel, higher r_ON (7–10 Ω), supports 3.3-V and 5-V operation, includes power-down mode.	Suitable for wider buses requiring more channels; less optimal for ultra-low-delay 4-line paths.	Choose when expanding beyond 4 lines or needing dual-supply flexibility; requires layout revision due to 24-pin TSSOP.
74LVC1G3157DP,125	Single-channel, lower r_ON (3–5 Ω), 1.65–5.5 V V_CC, smaller XSON-6 package.	Better for space-constrained point-of-use gating; not scalable to quad-channel requirements.	Prefer for discrete signal isolation; not a functional replacement for quad-bus switching without four instances.

Compared with SN74CBT3125CPWRG4, SN74CBTD3384PWR offers greater channel density but trades off speed and pin compatibility, while 74LVC1G3157DP,125 delivers superior on-resistance in a miniature footprint but lacks integrated quad functionality-making SN74CBT3125CPWRG4 optimal for balanced performance, density, and layout efficiency in 4-line bus architectures.

Availability

SN74CBT3125CPWRG4 is available at Aetrix Electronics and suitable for memory expansion interfaces, microcontroller peripheral multiplexing, legacy parallel bus isolation, and level-shifted data path gating requiring stable component supply and long-term industrial availability.

Supply support for SN74CBT3125CPWRG4 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 90 years of innovation in industrial, automotive, and communications markets.

The SN74CBT3125CPWRG4 belongs to TI's CBT (Crosspoint Bus Transceiver) family, engineered for high-speed, low-distortion signal routing in digital systems where minimal propagation delay and precise on-resistance control are essential.

FAQ

What is the maximum continuous current rating per channel of the SN74CBT3125CPWRG4?

The SN74CBT3125CPWRG4 supports a continuous channel current of 128 mA per switch, verified under recommended operating conditions (V_CC = 4–5.5 V, T_A = −40°C to 85°C). This rating assumes adequate PCB copper area for thermal dissipation and accounts for the device's 5–7 Ω on-resistance generating ≤1.02 W per channel at maximum current. Exceeding this limit risks thermal runaway or parametric shift.

Does the SN74CBT3125CPWRG4 require external pull-up resistors on its OE inputs?

Yes-the SN74CBT3125CPWRG4 OE inputs must be tied to V_CC through a pull-up resistor during power-up/down to guarantee high-impedance state. TI specifies minimum resistor value based on driver sink capability; typical designs use 10 kΩ. Without this, undefined OE states may cause partial conduction or bus contention, especially in systems with asynchronous power sequencing.

Can the SN74CBT3125CPWRG4 operate with a 3.3-V supply voltage?

No-the SN74CBT3125CPWRG4 has a specified V_CC range of 4.0 V to 5.5 V per its recommended operating conditions. At 3.3 V, the device fails to meet guaranteed r_ON, t_pd, and logic threshold specifications; observed behavior includes elevated on-resistance (>15 Ω) and unreliable switching. For 3.3-V systems, consider SN74CBTD3384 or 74LVC-series alternatives.

How does the SN74CBT3125CPWRG4 handle negative input voltages?

The SN74CBT3125CPWRG4 tolerates input voltages down to −0.5 V (absolute maximum rating), with input clamp current rated at −50 mA. When VI falls below GND, internal ESD diodes conduct into ground, limiting excursion depth. Sustained negative voltage beyond −0.5 V or clamp current exceeding −50 mA risks permanent damage; external series resistors are recommended for signals prone to overshoot or ESD coupling.

Is the SN74CBT3125CPWRG4 pin-compatible with other '125-type bus switches?

Yes-the SN74CBT3125CPWRG4 uses the industry-standard '125-type pinout across D, DB, DGV, PW, and RGY packages, matching SN74LS125, SN74ALS125, and SN74F125 in pin function and location. However, electrical characteristics differ significantly: CBT variants offer lower r_ON, faster timing, and CMOS-compatible inputs versus bipolar TTL predecessors, so direct substitution requires validation of timing margins and drive strength.

SN74CBT3125CPWRG4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74CBT

Package/Case:: 14-TSSOP (0.173", 4.40mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Discontinued at Digi-Key

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-TSSOP

SN74CBT3125CPWRG4 FAQ

1.How can I place an order for SN74CBT3125CPWRG4 through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74CBT3125CPWRG4 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 SN74CBT3125CPWRG4 reliable?

The price and inventory of SN74CBT3125CPWRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3125CPWRG4 is usually 5 days.

3.What payment methods are accepted for SN74CBT3125CPWRG4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74CBT3125CPWRG4 transactions.

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SN74CBT3125CPWRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74CBT3125CPWRG4 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 SN74CBT3125CPWRG4?

For technical support, including SN74CBT3125CPWRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3125CPWRG4 requirements.

6.How does Aetrix verify that SN74CBT3125CPWRG4 is sourced from the original manufacturer or authorized distributors?

All SN74CBT3125CPWRG4 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 SN74CBT3125CPWRG4 meets industry standards.

7.What is the process for return or replacement of SN74CBT3125CPWRG4?

All SN74CBT3125CPWRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3125CPWRG4, 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 SN74CBT3125CPWRG4 part is unused and in its original packaging.

Return procedure for SN74CBT3125CPWRG4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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