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Texas Instruments SN74CBT3245ADBQR
- Part No.:
- SN74CBT3245ADBQR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
SN74CBT3245ADBQR.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,915
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Product details
Overview
SN74CBT3245ADBQR 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 VCC = 5 V, and operates across −40°C to 85°C. It serves as a low-latency signal path control element in memory address/data bus isolation and hot-swap interface circuits.
For engineers reviewing the SN74CBT3245ADBQR datasheet, SN74CBT3245ADBQR pinout, SN74CBT3245ADBQR application, or SN74CBT3245ADBQR equivalent, key selection criteria include its 5-Ω Ron, 20-pin SSOP package, OE-controlled bidirectional switching, TTL-compatible input thresholds, and thermal impedance of 68°C/W - all critical for low-skew digital interconnect design.
Technical Context
This device implements eight independent NMOS transmission-gate switches with no internal level-shifting circuitry. Each A–B channel conducts bidirectionally when OE is low, exhibiting symmetrical on-resistance and minimal charge injection. The control logic uses standard TTL voltage thresholds (VIL ≤ 0.8 V, VIH ≥ 2 V) and requires OE to be pulled high via external resistor during power sequencing to guarantee high-impedance state.
Switching performance is load-dependent: tpd = 0.25 ns (typ) and ten/tdis ≈ 2–6 ns (VCC = 5 V, CL = 50 pF), with on-resistance specified at 5–7 Ω (VCC = 4.5 V, II = 30 mA). Input capacitance is 4 pF per control pin, and off-state I/O capacitance is 4 pF, minimizing capacitive loading on connected buses.
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 distortion across A/B ports under 30 mA load. |
| Propagation delay (tpd) | 0.25 ns (typ) at VCC = 5 V, CL = 50 pF - enables sub-nanosecond data path timing in high-speed bus architectures. |
| Supply voltage range | 4 V to 5.5 V - compatible with standard 5-V TTL and mixed-voltage system rails without level translation. |
| Input threshold (VIH/VIL) | VIH ≥ 2 V, VIL ≤ 0.8 V - directly interfaces with legacy TTL outputs without additional buffering. |
| Operating temperature | −40°C to +85°C - supports industrial-grade operation in embedded controllers and communications equipment. |
| Package thermal impedance (θJA) | 68°C/W (DBQ package) - defines maximum power dissipation limit (~150 mW at ΔT = 10°C) for thermal design margin. |
| Control input leakage (II) | ±5 μA max at VCC = 5.5 V - allows high-value pull-up resistors (>100 kΩ) on OE without compromising noise immunity. |
Pinout & Package
SN74CBT3245ADBQR is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, 7.4 mm × 5.3 mm body, and 2.0 mm max height. Pin 1 index is marked by a notch or dot; the package is RoHS-compliant with NIPDAU lead finish and MSL Level-1 rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 | Port A input/output terminals - bidirectionally connected to B1–B8 when OE is active low. |
| 9 | GND | Ground reference for all internal circuitry and signal return path. |
| 10 | VCC | Positive supply rail (4–5.5 V); powers internal FET gates and bias networks. |
| 11 | OE | Active-low output-enable control - drives all eight switches simultaneously into on/off state. |
| 12, 13, 14, 15, 16, 17, 18, 19 | B1–B8 | Port B input/output terminals - electrically mirrored to A1–A8 during conduction. |
| 20 | NC | No internal connection - must remain unconnected; not used for thermal pad or grounding. |
Key Features
| Feature | Design Value |
|---|---|
| Standard '245-type pinout | Enables drop-in replacement for legacy 74-series bus transceivers without PCB redesign. |
| Bidirectional signal routing | Eliminates need for direction-control logic or separate transmit/receive paths in shared-bus topologies. |
| Low on-state resistance (5 Ω) | Reduces insertion loss and maintains signal integrity for 5-V CMOS/TTL signals up to 100 MHz. |
| TTL-compatible control inputs | Directly accepts standard 5-V logic outputs without level shifters or pull-up resistors on A/B lines. |
| High-impedance isolation when disabled | Prevents back-driving and bus contention during power-up/down or standby modes. |
Applications
| Memory Address Bus Isolation | Hot-Swap Backplane Interface |
|---|---|
Use Scenario: Isolating CPU address lines from multiple memory modules to prevent contention during module insertion/removal. IC Role / Device Role / Timing Role: Bidirectional bus switch enabling/disabling address path between processor and memory banks under OE control. Use Value: Prevents signal corruption during live module swaps while maintaining <0.3 ns timing skew across all 8 address bits. |
Use Scenario: Managing data connectivity between a hot-pluggable peripheral card and host backplane in telecom line cards. IC Role / Device Role / Timing Role: OE-gated signal bridge that disconnects peripheral I/O before physical insertion and re-enables after stable power-up. Use Value: Eliminates need for complex sequenced enable logic; 5-Ω Ron ensures <10 mV voltage drop at 20 mA per line. |
| Legacy System Bus Expansion | Test Access Port Multiplexing |
Use Scenario: Adding secondary peripheral bus segments to aging microcontroller-based industrial controllers using existing '245 footprint. IC Role / Device Role / Timing Role: Pin-compatible bus extender replicating original 74LS245 functionality with improved speed and lower power. Use Value: Maintains backward compatibility while reducing propagation delay by >50% versus bipolar 245 devices. |
Use Scenario: Sharing JTAG TDI/TDO/TMS/TCK lines among multiple ASICs on a single test board using time-multiplexed access. IC Role / Device Role / Timing Role: Low-capacitance (4 pF) switch enabling clean signal routing between test controller and selected DUT. Use Value: Minimizes signal degradation and reflection on high-frequency JTAG clocks up to 25 MHz. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384CDWR | Higher Ron (7–10 Ω), 24-pin SOIC, includes 2-bit enable grouping and higher drive strength. | Supports split-bus configurations where subsets of lines require independent control. | Choose when granular enable control or higher current capability (128 mA per channel) is required. |
| 74LVC245APW | CMOS-based, 3.3-V only, 8-bit direction-controlled transceiver (not bidirectional switch), 3-state outputs. | Requires direction pin and is unsuitable for true bidirectional passive routing without external logic. | Choose only if system operates strictly at 3.3 V and direction control is acceptable overhead. |
Compared with SN74CBT3245ADBQR, SN74CBTD3384CDWR offers finer enable segmentation but larger footprint and higher Ron, while 74LVC245APW lacks true bidirectional pass-through behavior and mandates voltage-level alignment - making SN74CBT3245ADBQR optimal for low-latency, 5-V, OE-synchronized bus gating.
Availability
SN74CBT3245ADBQR is available at Aetrix Electronics and suitable for memory bus isolation, hot-swap interface design, and legacy system expansion requiring stable component supply and long-term industrial lifecycle support.
Supply support for SN74CBT3245ADBQR 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 90 years of innovation in industrial, automotive, and communications electronics.
The SN74CBT3245A family delivers high-speed, low-Ron FET bus switching for 5-V digital systems - engineered specifically for applications demanding minimal propagation delay, TTL compatibility, and robust hot-swap isolation.
FAQ
What is the maximum continuous current per channel for SN74CBT3245ADBQR?
The absolute maximum continuous channel current for SN74CBT3245ADBQR is 128 mA, as specified in the Absolute Maximum Ratings table. This value applies to each A–B switch path individually under steady-state conditions and must be derated based on ambient temperature and package thermal impedance (68°C/W for DBQ) to maintain junction temperature below 150°C.
Does SN74CBT3245ADBQR support 3.3-V operation?
No, SN74CBT3245ADBQR is not rated for 3.3-V operation. Its recommended operating supply voltage is 4 V to 5.5 V, and electrical characteristics including Ron, tpd, and VIH/VIL are guaranteed only within this range. Operating below 4 V may result in undefined switching behavior and increased on-resistance.
Can SN74CBT3245ADBQR be used in place of a 74LS245 in existing designs?
Yes, SN74CBT3245ADBQR uses the standard '245-type pinout and TTL-compatible input levels, allowing direct substitution for 74LS245 in most 5-V systems. However, it lacks direction control and operates as a bidirectional switch enabled by OE - verify that system logic drives OE appropriately instead of relying on DIR pin functionality.
What is the recommended pull-up resistor value for OE on SN74CBT3245ADBQR?
Texas Instruments recommends tying OE to VCC through a pull-up resistor to ensure high-impedance state during power-up. The minimum value depends on the driver's current-sinking capability; for typical microcontroller GPIO (±20 mA), a 10-kΩ resistor provides sufficient noise margin while limiting current to <0.5 mA at 5 V.
Is SN74CBT3245ADBQR pin-compatible with other packages in the same family?
Yes, SN74CBT3245ADBQR shares identical pin numbering and signal assignment with other variants including SN74CBT3245ADW (SOIC), SN74CBT3245APWR (TSSOP), and SN74CBT3245ARGYR (VQFN), all adhering to the standard 20-pin '245 layout. Mechanical dimensions differ, but schematic symbol and netlist mapping remain consistent.
SN74CBT3245ADBQR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 20-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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-SSOP
SN74CBT3245ADBQR FAQ
1.How can I place an order for SN74CBT3245ADBQR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3245ADBQR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
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The price and inventory of SN74CBT3245ADBQR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3245ADBQR 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 SN74CBT3245ADBQR?
For technical support, including SN74CBT3245ADBQR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3245ADBQR requirements.
6.How does Aetrix verify that SN74CBT3245ADBQR is sourced from the original manufacturer or authorized distributors?
All SN74CBT3245ADBQR 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 SN74CBT3245ADBQR meets industry standards.
7.What is the process for return or replacement of SN74CBT3245ADBQR?
All SN74CBT3245ADBQR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3245ADBQR, 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 SN74CBT3245ADBQR part is unused and in its original packaging.
Return procedure for SN74CBT3245ADBQR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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