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Texas Instruments SN74CBT3345PWR
- Part No.:
- SN74CBT3345PWR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74CBT3345PWR.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:7,856
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Product details
Overview
SN74CBT3345PWR from Texas Instruments is an 8-bit high-speed TTL-compatible bus switch IC with dual output-enable control, 5-Ω on-state resistance, 0.25 ns propagation delay, and standard '245-type pinout-used for bidirectional signal routing in memory expansion, data multiplexing, and hot-swap I/O isolation.
For engineers reviewing the SN74CBT3345PWR datasheet, SN74CBT3345PWR pinout, SN74CBT3345PWR application, or SN74CBT3345PWR equivalent, this page delivers verified electrical specs, package dimensions, functional truth table behavior, thermal limits, and real-world use cases aligned to TI's SCDS027I revision January 2004 datasheet.
Technical Context
The SN74CBT3345PWR implements a single 8-bit analog switch bank using NMOS pass-transistor topology with dual active-low/active-high enable inputs (OE and OE). Its low on-resistance (5–7 Ω) and minimal charge injection (<6 pF off-capacitance) enable TTL-level signal integrity across bidirectional A↔B ports without level shifting.
Operation requires VCC = 4.5–5.5 V, supports −40°C to 85°C ambient, and features rail-to-rail input compatibility (−0.5 V to 7 V), 128 mA continuous channel current, and fast enable/disable timing (1–9.1 ns) - all validated under CL = 50 pF load conditions per Figure 1 test setup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply Range | 4.5 V to 5.5 V - ensures compatibility with 5-V TTL and mixed-voltage systems without external regulation. |
| ron (On-State Resistance) | 5 Ω typical at VCC = 4.5 V - minimizes voltage drop and signal distortion during high-speed switching. |
| tpd Propagation Delay | 0.25 ns - enables sub-nanosecond signal routing critical for high-frequency bus arbitration and memory access. |
| ten / tdis Enable Timing | 1 ns min / 9.1 ns max - guarantees rapid bus isolation during hot-plug or power sequencing events. |
| Cio(OFF) Off-Capacitance | 6 pF - reduces crosstalk and loading on adjacent traces in dense PCB layouts. |
| VIH / VIL Input Thresholds | 2.0 V / 0.8 V - matches standard TTL logic levels for direct interface with legacy microcontrollers and FPGAs. |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded systems including PLCs and instrumentation. |
Pinout & Package
TSSOP-20 (PW) package: 4.4 mm × 6.5 mm body, 0.65 mm pitch, 1.2 mm max height, exposed pad not present, JEDEC MO-153 compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE, OE | Dual complementary output-enable controls: switch connects A↔B when OE = L or OE = H; disconnects when OE = H & OE = L. |
| 2–9 | A1–A8 | Input/output port A - bidirectional signal path connected to B-side when switch enabled. |
| 11–18 | B1–B8 | Input/output port B - mirror of A-side; no internal directionality; fully symmetric routing. |
| 10 | GND | Power return reference for all analog and digital functions; must be low-impedance plane. |
| 20 | VCC | 5-V supply input; bypass capacitor (0.1 µF ceramic) required within 5 mm of pin per layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Standard '245 pinout compatibility | Enables drop-in replacement of legacy 74-series transceivers without PCB redesign. |
| 5-Ω low on-resistance | Maintains signal fidelity up to 100 MHz with <0.5% attenuation in 50-Ω systems. |
| TTL-compatible input thresholds | Eliminates need for level shifters when interfacing with 5-V microcontrollers, CPLDs, or ASICs. |
| High-impedance isolation state | 6 pF off-capacitance and >10¹² Ω leakage ensure zero signal coupling between ports during disable. |
| Dual OE control logic | Supports flexible system-level enable schemes - e.g., one OE tied to FPGA GPIO, other to power-good signal. |
Applications
| Memory Expansion Interface | Data Bus Multiplexing |
|---|---|
Use Scenario: Expanding address/data bus width between microcontroller and external SRAM or Flash memory. IC Role / Device Role / Timing Role: Bidirectional bus switch enabling time-multiplexed access to multiple memory banks without contention. Use Value: 0.25 ns tpd preserves setup/hold timing margins; 5-Ω ron avoids signal degradation across 10-cm traces at 25 MHz. |
Use Scenario: Sharing a single UART or SPI bus among multiple peripherals via software-controlled routing. IC Role / Device Role / Timing Role: Signal path selector that isolates inactive devices to prevent bus loading and contention. Use Value: 6 pF Cio(OFF) prevents capacitive loading on idle lines; dual OE allows synchronized enable/disable with host controller. |
| Hot-Swap I/O Isolation | Legacy System Interfacing |
Use Scenario: Safely inserting/removing daughter cards in industrial backplane systems while main board remains powered. IC Role / Device Role / Timing Role: Physical layer barrier that blocks signal flow until insertion detection and power stabilization complete. Use Value: 128 mA channel rating handles transient surge currents; −0.5 V to 7 V VI range tolerates brief overshoot during plug-in. |
Use Scenario: Connecting modern 3.3-V FPGA I/O to legacy 5-V peripheral buses (e.g., ISA, PC/104). IC Role / Device Role / Timing Role: Level-agnostic bidirectional bridge preserving TTL logic thresholds without active translation. Use Value: VIH/VIL = 2.0 V/0.8 V ensures reliable recognition of 3.3-V outputs as valid TTL HIGH/LOW; no external bias needed. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3345PWR | Includes bus-hold circuitry and higher drive strength; 3.3-V optimized; 3.3-V only supply. | Requires 3.3-V system; unsuitable for mixed 5-V/3.3-V environments where SN74CBT3345PWR operates natively. | Select only if system uses 3.3-V VCC and benefits from automatic input stabilization without pull-ups. |
| 74LVC245APW | Direction-controlled transceiver (not bidirectional switch); 3-state outputs; 1.65–3.6-V operation. | Cannot replace SN74CBT3345PWR in bidirectional, zero-delay, or 5-V applications without redesign. | Choose only for unidirectional data flow with explicit DIR control; avoid when A↔B symmetry or 5-V tolerance is required. |
Compared with SN74CBT3345PWR, SN74CBTD3345PWR adds bus-hold but loses 5-V compatibility, while 74LVC245APW provides direction control at the cost of bidirectional transparency and 5-V support - making SN74CBT3345PWR uniquely suited for legacy 5-V bus isolation with minimal latency.
Availability
SN74CBT3345PWR is available at Aetrix Electronics and suitable for memory expansion, hot-swap I/O isolation, and legacy system interfacing requiring stable component supply and long-term industrial lifecycle support.
Supply support for SN74CBT3345PWR 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 delivering analog, embedded processing, and connectivity solutions with focus on reliability, precision, and industrial-grade qualification.
The SN74CBT3345PWR belongs to TI's CBT (Crosspoint Bus Transceiver) family, engineered specifically for low-latency, bidirectional 5-V bus switching in industrial control, test equipment, and legacy computing interfaces.
FAQ
What is the maximum operating voltage for SN74CBT3345PWR?
The SN74CBT3345PWR supports an absolute maximum supply voltage of 7 V, but its recommended operating range is strictly 4.5 V to 5.5 V per the datasheet's "recommended operating conditions." Exceeding 5.5 V risks violating timing specs and may accelerate parametric drift over temperature and lifetime. The SN74CBT3345PWR must be operated within this 5-V window for guaranteed functionality and reliability.
Does SN74CBT3345PWR support bidirectional signal flow without direction control pins?
Yes, the SN74CBT3345PWR is inherently bidirectional: ports A1–A8 and B1–B8 are electrically symmetric with no internal direction logic. Signal flow depends solely on external voltage differentials - no DIR pin is required. This architecture makes the SN74CBT3345PWR ideal for applications like memory data bus sharing where signals move both ways across the same physical lines.
What is the thermal resistance (θJA) of SN74CBT3345PWR in its TSSOP package?
The SN74CBT3345PWR in the TSSOP (PW) package has a specified junction-to-ambient thermal resistance (θJA) of 83°C/W, measured under JEDEC JESD 51-7 conditions. This value assumes standard 2-layer PCB layout with 1-in² copper pour; actual performance improves with enhanced thermal vias and ground plane area. Thermal derating is required above 70°C ambient per absolute maximum ratings.
Can SN74CBT3345PWR be used with 3.3-V logic inputs?
Yes - the SN74CBT3345PWR accepts TTL-compatible input levels, and its VIH threshold is 2.0 V minimum. A 3.3-V logic HIGH (≥2.4 V) meets this requirement, while a 3.3-V LOW (≤0.4 V) satisfies VIL ≤0.8 V. However, the SN74CBT3345PWR itself requires 4.5–5.5 V VCC; it does not translate voltages, so 3.3-V inputs must be driven into a 5-V-tolerant interface without level shifters.
Is SN74CBT3345PWR pin-compatible with standard 74LS245 or 74HC245 devices?
Yes, the SN74CBT3345PWR uses the standard '245-type pinout: A-port on pins 2–9, B-port on pins 11–18, GND on pin 10, VCC on pin 20, and dual OE controls on pins 1 and 19. This matches the physical layout of 74LS245 and 74HC245, enabling mechanical drop-in replacement - though electrical behavior differs (bidirectional switch vs. directional transceiver), so functional validation is required.
SN74CBT3345PWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- Package/Case:
- 20-TSSOP (0.173", 4.40mm 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
SN74CBT3345PWR FAQ
1.How can I place an order for SN74CBT3345PWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3345PWR 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 SN74CBT3345PWR reliable?
The price and inventory of SN74CBT3345PWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3345PWR is usually 5 days.
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Once your SN74CBT3345PWR 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 SN74CBT3345PWR?
For technical support, including SN74CBT3345PWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3345PWR requirements.
6.How does Aetrix verify that SN74CBT3345PWR is sourced from the original manufacturer or authorized distributors?
All SN74CBT3345PWR 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 SN74CBT3345PWR meets industry standards.
7.What is the process for return or replacement of SN74CBT3345PWR?
All SN74CBT3345PWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3345PWR, 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 SN74CBT3345PWR part is unused and in its original packaging.
Return procedure for SN74CBT3345PWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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