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Texas Instruments SN74CBT3245ADW
- Part No.:
- SN74CBT3245ADW
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74CBT3245ADW.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:715
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Product details
Overview
SN74CBT3245ADW from Texas Instruments is an octal FET bus switch IC designed for high-speed TTL-compatible bidirectional data routing between two 8-bit ports (A and B). It features 5-Ω on-state resistance, 0.25 ns typical propagation delay at 5 V, and operates from −40°C to 85°C with 4–5.5 V supply. It serves in address/data bus isolation and hot-swap interface circuits.
For engineers reviewing the SN74CBT3245ADW datasheet, SN74CBT3245ADW pinout, SN74CBT3245ADW application, or SN74CBT3245ADW equivalent, key selection criteria include on-resistance matching, OE-controlled bidirectional switching, SOIC-20 thermal performance (θJA = 58°C/W), and TTL-level input compatibility without level translation.
Technical Context
The SN74CBT3245ADW implements eight independent FET transmission gates controlled by a single active-low output-enable (OE) signal. When OE is low, all A–B paths conduct with minimal RC delay; when OE is high, both ports enter high-impedance states. Its architecture avoids latch-up and supports hot-insertion due to rail-to-rail voltage tolerance (−0.5 V to 7 V).
It uses standard '245-type pinout in SOIC-20 (DW) package, enabling drop-in replacement in legacy 74-series bus switch layouts. The device requires no external biasing-TTL-compatible VIH/VIL thresholds (2 V/0.8 V) allow direct interfacing with 5-V logic families without pull-up/down resistors on data lines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4 V to 5.5 V - Ensures compatibility with 5-V TTL and mixed-supply systems without overvoltage risk. |
| ron (Typ) | 5 Ω - Enables <10 mV voltage drop at 30 mA per channel, preserving signal integrity across bus segments. |
| tpd (Typ) | 0.25 ns at VCC = 5 V - Supports >1 GHz effective switching rates for high-speed digital interconnects. |
| IOH/IOL | ±128 mA continuous channel current - Sustains full drive capability across all eight channels simultaneously. |
| VIH/VIL | 2 V / 0.8 V - Directly interfaces with standard 5-V TTL outputs without level-shifting circuitry. |
| θJA | 58°C/W - Confirmed for SOIC-20 (DW) package; enables thermal design up to ~150 mW power dissipation at 85°C ambient. |
| Cio(OFF) | 4 pF - Limits capacitive loading during disable state, critical for maintaining signal rise/fall times in high-frequency buses. |
Pinout & Package
SN74CBT3245ADW is housed in a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body size, 2.65 mm max height, with 1.27 mm lead pitch and gull-wing leads. Pin 1 index area located at top-left corner with notch marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 | Port A data inputs/outputs - Bidirectionally connected to Port B when OE is low; high-Z when OE is high. |
| 9 | GND | Ground reference - Must be low-impedance connection to minimize noise coupling into analog switch paths. |
| 10 | VCC | Positive supply - Powers internal FET gates; decoupling capacitor (0.1 µF) required within 1 cm of this pin. |
| 11 | OE | Active-low output enable - Driven low to enable A↔B conduction; tied to VCC via pull-up resistor for power-up high-Z safety. |
| 12, 13, 14, 15, 16, 17, 18, 19 | B1–B8 | Port B data inputs/outputs - Electrically identical to A-side; no directionality imposed by IC. |
| 20 | NC | No internal connection - Left unconnected; not used for thermal pad or grounding in SOIC-20 DW package. |
Key Features
| Feature | Design Value |
|---|---|
| 5-Ω on-state resistance | Minimizes insertion loss and voltage droop across 8-bit data/address paths, preserving logic margins in 5-V systems. |
| Standard '245 pinout | Enables mechanical and layout compatibility with legacy 74LS245/74ACT245 designs without PCB revision. |
| TTL-compatible control inputs | Eliminates need for external level shifters when driven by 5-V microcontrollers, FPGAs, or ASICs. |
| High-impedance off-state | Isolates A and B ports with <1 μA leakage, preventing back-driving and bus contention during power sequencing. |
| Rail-to-rail I/O voltage range | Supports signals from −0.5 V to 7 V, allowing safe operation during hot-swap events and mixed-voltage domain crossings. |
Applications
| Memory Address Bus Isolation | PCI/ISA Bus Buffering |
|---|---|
Use Scenario: Isolating CPU address lines from multiple memory banks to prevent contention during bank switching. IC Role / Device Role / Timing Role: Bidirectional 8-bit bus switch controlled by memory controller's chip-select strobe. Use Value: 5-Ω ron ensures <50 mV address line droop at 100 mA peak current, maintaining setup/hold timing margins. | Use Scenario: Buffering shared ISA bus signals between legacy I/O cards and host bridge logic. IC Role / Device Role / Timing Role: Hot-swap-capable bus isolator enabling card insertion/removal without system reset. Use Value: Rail-to-rail I/O tolerance (−0.5 V to 7 V) prevents latch-up during live insertion transients. |
| Microcontroller Peripheral Multiplexing | Test Access Port (TAP) Signal Routing |
Use Scenario: Sharing a single 8-bit GPIO port between UART, SPI, and parallel LCD interfaces via software-controlled routing. IC Role / Device Role / Timing Role: Low-latency (0.25 ns tpd) bidirectional switch enabling real-time peripheral reconfiguration. Use Value: 4 pF off-state capacitance minimizes signal degradation on 10-MHz SPI clock lines routed through the switch. | Use Scenario: Dynamically routing JTAG TDI/TDO/TMS signals between multiple FPGA test chains on a single board. IC Role / Device Role / Timing Role: OE-gated signal path selector synchronized to boundary-scan controller enable pulses. Use Value: High-impedance off-state (<1 μA leakage) prevents false TCK edge detection during chain reconfiguration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384ADWR | Higher 10-Ω ron, 3.3-V only supply, 24-pin SSOP - includes dual 4-bit configuration with separate OE per group. | Requires 3.3-V system integration; less suitable for 5-V legacy buses but better for low-power embedded designs. | Select when lower static current (ICC = 10 μA) and 3.3-V operation are prioritized over speed and 5-V compatibility. |
| 74LVC245APW | CMOS-based 8-bit transceiver with direction control (DIR), 3.3-V supply, 20-pin TSSOP - not a FET switch; has push-pull outputs. | Requires explicit direction control logic; unsuitable for true bidirectional passive switching but offers higher drive strength (24 mA). | Choose when active driving (not passive switching) is needed, and direction is known a priori - e.g., unidirectional data transfer with flow control. |
Compared with SN74CBT3245ADW, SN74CBTD3384ADWR trades speed and voltage range for lower power and finer channel granularity, while 74LVC245APW replaces passive FET switching with active CMOS buffering-requiring DIR signal routing and sacrificing true bidirectional transparency.
Availability
SN74CBT3245ADW is available at Aetrix Electronics and suitable for memory bus isolation, industrial PLC backplane interfaces, and legacy 5-V embedded system upgrades requiring stable component supply and long-term obsolescence management.
Supply support for SN74CBT3245ADW 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 SN74CBT3245ADW belongs to TI's CBT (Crosspoint Bus Transceiver) family, engineered specifically for low-latency, low-distortion 5-V bus switching in legacy computing, instrumentation, and control systems.
FAQ
What is the maximum operating temperature range for the SN74CBT3245ADW?
The SN74CBT3245ADW is rated for operation from −40°C to +85°C ambient temperature. This industrial-grade range is validated per TI's recommended operating conditions and supported by thermal characterization (θJA = 58°C/W for SOIC-20). Derating applies above 70°C ambient if power dissipation exceeds 100 mW.
Does the SN74CBT3245ADW require external pull-up resistors on the OE pin?
Yes - to ensure high-impedance state during power-up or power-down, OE must be tied to VCC via a pull-up resistor. TI specifies minimum resistance based on driver sink capability; for standard TTL drivers, 4.7 kΩ is commonly used. Leaving OE floating risks undefined switching behavior and potential bus contention.
Can the SN74CBT3245ADW operate with a 3.3-V supply?
No - the SN74CBT3245ADW requires VCC between 4 V and 5.5 V per its recommended operating conditions. At 3.3 V, the internal FETs fail to fully enhance, resulting in elevated on-resistance (>20 Ω), increased propagation delay, and possible logic threshold violations. Use SN74CBTD3384A for 3.3-V systems.
Is the SN74CBT3245ADW pin-compatible with the original 74LS245?
Yes - the SN74CBT3245ADW uses standard '245-type pinout in SOIC-20 (DW), matching pin-for-pin with 74LS245, 74ACT245, and other industry-standard octal transceivers. However, it functions as a bidirectional switch (not a transceiver), so direction control logic is unnecessary - OE replaces DIR.
What is the off-state capacitance of the SN74CBT3245ADW, and why does it matter?
The SN74CBT3245ADW has Cio(OFF) = 4 pF per channel when disabled. This low value limits capacitive loading on high-speed buses (e.g., 10+ MHz address/data lines), preserving signal edge rates and reducing crosstalk. In contrast, higher off-capacitance (>10 pF) would degrade rise/fall times and increase reflection-induced jitter.
SN74CBT3245ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Type:
- Bus Switch
- Circuit:
- 8 x 1:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- -
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74CBT3245ADW FAQ
1.How can I place an order for SN74CBT3245ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3245ADW 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 SN74CBT3245ADW reliable?
The price and inventory of SN74CBT3245ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3245ADW is usually 5 days.
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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 SN74CBT3245ADW?
For technical support, including SN74CBT3245ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3245ADW requirements.
6.How does Aetrix verify that SN74CBT3245ADW is sourced from the original manufacturer or authorized distributors?
All SN74CBT3245ADW 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 SN74CBT3245ADW meets industry standards.
7.What is the process for return or replacement of SN74CBT3245ADW?
All SN74CBT3245ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3245ADW, 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 SN74CBT3245ADW part is unused and in its original packaging.
Return procedure for SN74CBT3245ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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