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Texas Instruments SN74CBT3257DBR
- Part No.:
- SN74CBT3257DBR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74CBT3257DBR.pdf
- Description:
- IC MUX/DEMUX 4 X 2:1 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:203
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Product details
Overview
SN74CBT3257DBR from Texas Instruments is a 4-bit 1-of-2 FET multiplexer/demultiplexer in SSOP-16 package, featuring 5 Ω typical on-state resistance, TTL-compatible control inputs (VIH = 2 V, VIL = 0.8 V), and sub-1 ns propagation delay (tpd = 0.25 ns at VCC = 5 V). It enables bidirectional signal routing in high-speed digital interconnects such as bus isolation and data path switching.
For engineers reviewing the SN74CBT3257DBR datasheet, SN74CBT3257DBR pinout, SN74CBT3257DBR application, or SN74CBT3257DBR equivalent, key selection criteria include low on-resistance for minimal signal attenuation, OE/S-controlled channel selection timing, bidirectional operation without direction pins, and compatibility with 4.0–5.5 V supply rails in industrial logic systems.
Technical Context
The SN74CBT3257DBR implements four independent analog/digital switches using NMOS pass-transistor architecture, each selectable between two B-side terminals (B1/B2) via shared S (select) and OE (output-enable) controls. Its TTL-compatible inputs interface directly with standard logic families without level-shifting.
Each switch operates bidirectionally with no internal diodes or direction control-signal flow is determined solely by external voltage differentials. The device maintains high off-isolation (>4 pF Cio(OFF)) and low input capacitance (3.5 pF Ci), supporting clean edge integrity in 50 pF load environments up to 100 MHz effective bandwidth.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| On-state resistance (ron) | 5 Ω typical - ensures minimal voltage drop and signal distortion for ≤64 mA channel current. |
| Propagation delay (tpd) | 0.25 ns at VCC = 5 V - supports sub-nanosecond timing-critical routing in high-speed buses. |
| Supply voltage range | 4.0 V to 5.5 V - compatible with 5 V TTL and mixed-voltage logic domains. |
| Control input thresholds | VIH = 2.0 V, VIL = 0.8 V - direct interfacing with standard 5 V CMOS/TTL outputs. |
| Off-isolation capacitance | 4 pF Cio(OFF) - limits crosstalk between inactive channels in dense PCB layouts. |
| Input capacitance (Ci) | 3.5 pF - reduces loading on driving logic, preserving rise/fall times in fanout-sensitive nodes. |
| Operating temperature | −40°C to +85°C - qualified for industrial-grade embedded and communications equipment. |
Pinout & Package
SN74CBT3257DBR uses a 16-pin SSOP (Shrink Small-Outline Package) with 0.65 mm lead pitch, 7.4 mm × 5.3 mm body size, and 1.75 mm max height per JEDEC MO-137 variation AB. Pin 1 index is marked by a beveled corner or dot.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 15, 16, 2, 3, 5, 6, 11, 10, 14, 13, 12 | Data I/O (A1–A4, B1_1–B2_4) | Bidirectional signal paths: A port connects to selected B1 or B2 terminal per channel under S/OE control. |
| 4 | Select (S) | Chooses B1 (S = L) or B2 (S = H) for all four channels simultaneously; active-low logic not used. |
| 7 | GND | Ground reference for switch body ties and logic threshold stability. |
| 8 | VCC | Positive supply (4.0–5.5 V); powers internal FET bias and input buffers. |
| 9 | OE (Output Enable) | Active-low enable: OE = L activates switches; OE = H disconnects all A–B paths (high-impedance state). |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low on-resistance | 5 Ω typical - preserves signal amplitude and timing margins in 50 Ω–100 Ω transmission lines. |
| TTL-compatible control interface | VIH = 2.0 V / VIL = 0.8 V - eliminates need for external level shifters when driven by legacy 5 V logic. |
| Break-before-make switching | Guaranteed by OE/S timing - prevents momentary shorting between B1 and B2 during select transitions. |
| Bidirectional signal flow | No direction pin required - simplifies PCB routing and supports data flow in either direction per channel. |
| Low dynamic power consumption | ICC = 3 μA max - negligible quiescent load on VCC rail during static operation. |
Applications
| PCI Bus Isolation | Memory Address Multiplexing |
|---|---|
|
Use Scenario: Isolating PCI slot signals from motherboard logic to prevent noise coupling and support hot-plug detection. IC Role / Device Role / Timing Role: Bidirectional analog switch enabling/disabling data/address lines between PCI agent and host bridge under OE control. Use Value: 5 Ω ron minimizes insertion loss across 33 MHz PCI bus traces; sub-1 ns tpd avoids skew-induced setup/hold violations. |
Use Scenario: Sharing address lines between multiple memory banks (e.g., SRAM and Flash) in microcontroller-based systems. IC Role / Device Role / Timing Role: 1-of-2 demux selecting which memory bank receives the common address bus based on chip-select logic. Use Value: TTL-compatible inputs synchronize cleanly with MCU GPIO; low Cio(OFF) prevents address leakage between banks. |
| FPGA I/O Expansion | Digital Test Access Port Switching |
|
Use Scenario: Expanding limited FPGA I/O pins to drive multiple peripheral interfaces (e.g., UART, SPI, I²C) via time-shared routing. IC Role / Device Role / Timing Role: Multiplexer steering FPGA GPIO signals to one of two peripheral sets using S/OE from configuration logic. Use Value: 0.25 ns tpd ensures timing closure in 100+ MHz FPGA clock domains; bidirectional operation supports full-duplex protocols. |
Use Scenario: Routing JTAG TDI/TDO/TMS/TCK signals between multiple ASICs on a test board without physical rework. IC Role / Device Role / Timing Role: Manual or firmware-controlled switch enabling test access to one DUT at a time while isolating others. Use Value: High off-isolation (4 pF Cio) prevents signal bleed between unselected devices; OE pin allows global test-bus disable. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FET multiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384DBR | 8-bit, dual 1-of-2, 3.3 V only (VCC = 2.3–3.6 V), lower ron (3.5 Ω), higher speed (tpd = 0.18 ns) | Requires 3.3 V supply and level translation for 5 V systems; suited for modern low-voltage SoC interconnects. | Select when migrating to 3.3 V logic and higher channel count is needed; not drop-in for 5 V designs. |
| 74LVC1G3157GW | Single-channel, 1.65–5.5 V supply, ron = 6 Ω, tpd = 0.3 ns, SC-70-6 package | Lower integration density; requires four units for equivalent 4-bit function; smaller footprint but higher assembly cost. | Choose for space-constrained designs where discrete channel control is preferred over quad integration. |
Compared with SN74CBT3257DBR, SN74CBTD3384DBR offers higher performance at lower voltage but lacks 5 V compatibility, while 74LVC1G3157GW trades integration for flexibility and voltage range-neither is pin-compatible, requiring layout revision.
Availability
SN74CBT3257DBR is available at Aetrix Electronics and suitable for industrial control backplanes, legacy 5 V communication modules, and FPGA prototyping platforms requiring stable component supply and long-term obsolescence management.
Supply support for SN74CBT3257DBR 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 U.S.-based semiconductor company specializing in analog, embedded processing, and logic solutions with broad industrial and automotive qualification.
The SN74CBT3257DBR belongs to TI's CBT (Crossbar Bus Transceiver) logic family, designed specifically for low-distortion, high-speed signal routing in 5 V digital systems where minimal propagation delay and bidirectional transparency are critical.
FAQ
What is the maximum continuous current rating per channel of the SN74CBT3257DBR?
The SN74CBT3257DBR supports a continuous channel current of 128 mA per switch, verified under absolute maximum ratings. This rating applies across the full operating temperature range (−40°C to +85°C) and ensures reliable conduction without thermal runaway when used within recommended VCC (4.0–5.5 V) and load conditions.
Does the SN74CBT3257DBR support bidirectional signal flow without additional control signals?
Yes, the SN74CBT3257DBR supports fully bidirectional signal flow on all A and B ports without direction pins or internal diodes. Signal direction is determined solely by external voltage potential-data can pass from A to B1/B2 or from B1/B2 to A depending on the connected circuit, making it ideal for bus-sharing and test-access applications.
What is the thermal resistance (θJA) of the SN74CBT3257DBR in its SSOP-16 package?
The SN74CBT3257DBR in DB package has a junction-to-ambient thermal resistance (θJA) of 82°C/W, measured per JESD 51-7. This value assumes standard JEDEC 2-layer board conditions and informs thermal design margining-maximum power dissipation should remain below 65 mW to limit junction temperature rise to <5.4°C above ambient at full load.
Can the SN74CBT3257DBR be used with 3.3 V control logic?
No-the SN74CBT3257DBR requires VCC = 4.0–5.5 V and specifies TTL-compatible input thresholds (VIH = 2.0 V, VIL = 0.8 V), but its internal FET biasing is optimized for 5 V operation. Driving OE or S with 3.3 V logic may result in marginal or undefined switching behavior; use level translators or select 3.3 V–compatible alternatives like SN74CBTD3384DBR instead.
Is the SN74CBT3257DBR pin-compatible with other members of the SN74CBT3257 family?
Yes-SN74CBT3257DBR shares identical pinout and function with SN74CBT3257DR (SOIC), SN74CBT3257PWR (TSSOP), and SN74CBT3257RGYR (QFN), differing only in package dimensions and thermal characteristics. All variants implement the same logic diagram, function table, and electrical specifications, enabling direct PCB footprint substitution where mechanical constraints allow.
SN74CBT3257DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 16-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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
SN74CBT3257DBR FAQ
1.How can I place an order for SN74CBT3257DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3257DBR 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 SN74CBT3257DBR reliable?
The price and inventory of SN74CBT3257DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3257DBR is usually 5 days.
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SN74CBT3257DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3257DBR 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 SN74CBT3257DBR?
For technical support, including SN74CBT3257DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3257DBR requirements.
6.How does Aetrix verify that SN74CBT3257DBR is sourced from the original manufacturer or authorized distributors?
All SN74CBT3257DBR 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 SN74CBT3257DBR meets industry standards.
7.What is the process for return or replacement of SN74CBT3257DBR?
All SN74CBT3257DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3257DBR, 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 SN74CBT3257DBR part is unused and in its original packaging.
Return procedure for SN74CBT3257DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74CBT3257DBR Tags
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