My Inquiry
My Account
Texas Instruments SN74CBT3125D
- Part No.:
- SN74CBT3125D
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74CBT3125D.pdf
- Description:
- IC BUS SWITCH 1 X 1:1 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,210
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74CBT3125D 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 and level-shifting interfaces, commonly used in memory expansion, peripheral multiplexing, and hot-swap I/O isolation circuits.
For engineers reviewing the SN74CBT3125D datasheet, SN74CBT3125D pinout, SN74CBT3125D application, or SN74CBT3125D equivalent, key selection criteria include on-resistance (5–7 Ω), propagation delay (0.25–0.35 ns), enable/disable timing (1.6–6 ns), thermal resistance (86°C/W), and SOIC-14 package compatibility with legacy board layouts.
Technical Context
This device implements four independent NMOS transmission gates controlled by active-low OE inputs. Each switch connects A and B ports when OE is low, presenting high-impedance isolation when OE is high - enabling dynamic bus segmentation without signal contention.
It operates as a passive analog switch with no internal logic or level translation; signal integrity depends on external biasing and load capacitance (CL = 50 pF specified). The design requires pull-up resistors on OE pins to ensure high-impedance state during power sequencing, per TI's recommended startup guidance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 4.0–5.5 V - defines compatible logic families (TTL/5V CMOS) and maximum signal swing |
| On-State Resistance (ron) | 5–7 Ω at 4–4.5 V - ensures minimal voltage drop and signal attenuation for ≤64 mA channel current |
| Propagation Delay (tpd) | 0.25–0.35 ns - supports >1 GHz digital switching in high-speed bus applications |
| Enable Time (ten) | 1.6–6 ns - determines minimum pulse width for reliable switch activation |
| Disable Time (tdis) | 1–5.1 ns - critical for glitch-free bus arbitration and hot-plug transitions |
| Input Capacitance (Ci) | 3 pF - limits capacitive loading on driving logic and preserves edge rate |
| Off-State Capacitance (Cio) | 4 pF - minimizes crosstalk and feedthrough between isolated channels |
Pinout & Package
SN74CBT3125D uses a 14-pin SOIC (D) package with 1.27 mm pitch, 8.75 × 3.91 mm body, and 1.75 mm max height - compatible with standard SOIC footprints and reflow profiles (MSL Level-1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 7, 10 (1OE–4OE) | Output Enable (active-low) | Controls individual switch conduction; must be pulled high via resistor for safe power-up state |
| 2, 5, 12, 15 (1A–4A) | Port A input/output | Bidirectional signal terminal connected to upstream logic or controller |
| 3, 6, 13, 16 (1B–4B) | Port B input/output | Bidirectional signal terminal connected to downstream bus or peripheral |
| 8 (GND) | Ground reference | Common return path for all switches and control circuitry |
| 14 (VCC) | Power supply | Provides operating voltage for internal FETs and input buffers |
| 11, 14 (NC) | No internal connection | Unbonded pins - must remain unconnected per TI design guidelines |
Key Features
| Feature | Design Value |
|---|---|
| Quadruple independent switches | Enables concurrent routing of four separate signals without shared control or timing constraints |
| 5-Ω typical on-resistance | Preserves signal amplitude and rise/fall times for 3.3V/5V logic interfacing |
| TTL-compatible inputs | Accepts standard 0.8 V / 2.0 V logic thresholds without level-shifter circuitry |
| Low 4 pF off-capacitance | Reduces crosstalk and maintains signal integrity in dense PCB layouts |
| Fast 1.6 ns enable time | Supports real-time bus arbitration in microcontroller-based peripheral switching |
Applications
| Memory Expansion Interface | Peripheral Multiplexer |
|---|---|
Use Scenario: Expanding address/data bus width between MCU and external SRAM or Flash memory. IC Role / Device Role / Timing Role: Bidirectional bus switch isolating memory banks during access arbitration. Use Value: Enables dynamic bank selection with sub-nanosecond propagation delay and <5 Ω on-resistance to minimize timing skew. | Use Scenario: Sharing UART, SPI, or I²C lines among multiple peripherals on a single microcontroller. IC Role / Device Role / Timing Role: Signal path selector that prevents bus contention during peripheral handshaking. Use Value: Provides 4-channel isolation with independent OE control, allowing staggered peripheral activation without software overhead. |
| Hot-Swap I/O Isolation | Logic-Level Translation Bridge |
Use Scenario: Safely connecting/removing USB or RS-232 transceivers while system remains powered. IC Role / Device Role / Timing Role: High-impedance barrier inserted between host controller and hot-pluggable module. Use Value: Guarantees zero-current injection during insertion/removal using fast disable (<5.1 ns) and robust ±0.5 V absolute max ratings. | Use Scenario: Interfacing 3.3 V FPGA I/O with 5 V sensor outputs in industrial data acquisition systems. IC Role / Device Role / Timing Role: Passive voltage-domain bridge maintaining signal fidelity without active level shifting. Use Value: Supports bidirectional 5 V-tolerant signaling with 3 pF input capacitance to avoid degrading FPGA drive strength or timing margins. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FET bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384D | Higher 128 mA continuous channel current; includes output-enable inversion logic | Designed for higher-drive applications like backplane switching; not pin-compatible | Select when >64 mA per channel or inverted OE polarity is required |
| 74LVC1G3157DBVR | Single-channel, 3.3 V only (1.65–5.5 V), lower 6 Ω ron, smaller SOT-23-6 package | Used for discrete signal routing rather than quad-bus consolidation | Choose for space-constrained designs needing one switch instead of four |
Compared with SN74CBT3125D, SN74CBTD3384D offers higher current handling but requires PCB redesign due to different pinout and logic polarity, while 74LVC1G3157DBVR reduces footprint and cost for single-line isolation but increases component count for quad-channel needs.
Availability
SN74CBT3125D is available at Aetrix Electronics and suitable for memory expansion, peripheral multiplexing, hot-swap I/O isolation, and logic-level bridging applications requiring stable component supply across industrial and embedded product lifecycles.
Supply support for SN74CBT3125D 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 SN74CBT3125D belongs to TI's CBT (CrossBar Technology) family of FET bus switches, engineered for ultra-low on-resistance and nanosecond switching in high-speed digital interconnect applications.
FAQ
What is the maximum continuous current rating per channel for SN74CBT3125D?
The SN74CBT3125D supports a continuous channel current of 128 mA per switch, verified under recommended operating conditions (VCC = 4–5.5 V, TA = −40°C to 85°C). This rating ensures reliable conduction without thermal derating in typical SOIC-14 PCB layouts with moderate copper area. Exceeding this limit risks junction overheating and long-term reliability degradation.
Does SN74CBT3125D require external pull-up resistors on its OE pins?
Yes - TI explicitly recommends tying each OE pin to VCC through a pull-up resistor to guarantee high-impedance state during power-up or power-down sequences. The minimum resistor value depends on the driver's current-sinking capability; typical values range from 4.7 kΩ to 10 kΩ for standard logic drivers. Leaving OE floating violates the recommended operating conditions and may cause undefined switch states.
Can SN74CBT3125D operate with a 3.3 V supply voltage?
No - SN74CBT3125D has a minimum recommended VCC of 4.0 V and absolute maximum of 7.0 V. Operation below 4.0 V is outside specification and may result in elevated on-resistance (>10 Ω), increased propagation delay, or failure to recognize TTL input thresholds. For 3.3 V systems, consider TI's 74LVC series or other 1.65–5.5 V compatible bus switches.
Is SN74CBT3125D pin-compatible with other CBT-family devices in SOIC-14 packages?
SN74CBT3125D shares the standard '125-type pinout with SN74CBT1125D and SN74CBT3384D in D-package variants, but functional differences exist: SN74CBT1125D lacks independent OE controls (uses single OE), and SN74CBT3384D includes inverted OE logic and higher current rating. Always verify function table and timing before substitution.
What is the thermal resistance (θJA) of SN74CBT3125D in its SOIC-14 package?
The SN74CBT3125D in SOIC-14 (D) package has a published junction-to-ambient thermal resistance (θJA) of 86°C/W, measured per JESD 51-7. This value assumes standard JEDEC 2-layer test board conditions; actual performance improves with added copper pour or thermal vias. At 128 mA per channel and 5.5 V supply, worst-case power dissipation remains below 100 mW, keeping temperature rise manageable in most layouts.
SN74CBT3125D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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
SN74CBT3125D FAQ
1.How can I place an order for SN74CBT3125D through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3125D 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 SN74CBT3125D reliable?
The price and inventory of SN74CBT3125D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3125D is usually 5 days.
3.What payment methods are accepted for SN74CBT3125D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74CBT3125D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74CBT3125D?
SN74CBT3125D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3125D 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 SN74CBT3125D?
For technical support, including SN74CBT3125D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3125D requirements.
6.How does Aetrix verify that SN74CBT3125D is sourced from the original manufacturer or authorized distributors?
All SN74CBT3125D 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 SN74CBT3125D meets industry standards.
7.What is the process for return or replacement of SN74CBT3125D?
All SN74CBT3125D units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3125D, 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 SN74CBT3125D part is unused and in its original packaging.
Return procedure for SN74CBT3125D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74CBT3125D Tags
-
SN74HC138DR
Texas Instruments
-
TC7SB3157CFU,LF(CT
Toshiba Semiconductor and Storage
-
74CBTLV3257PW,118
Nexperia USA Inc.
-
SN74CBTLV3257PWR
Texas Instruments
-
74CBTLV3257GUX
Nexperia USA Inc.
-
74HC154BQ,118
Nexperia USA Inc.
-
P3S0200GMX
NXP USA Inc.
-
SN74CB3Q3245PWR
Texas Instruments
-
SN74CB3Q3257RGYR
Texas Instruments
-
TCA9543APWR
Texas Instruments
-
TCA9546APWR
Texas Instruments
-
SN74HC138N
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
