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Texas Instruments SN74CB3T3245DWR
- Part No.:
- SN74CB3T3245DWR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74CB3T3245DWR.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:5,071
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Product details
Overview
SN74CB3T3245DWR from Texas Instruments is an 8-bit FET bus switch with bidirectional data flow, 5V-tolerant I/Os, and VCC-referenced level shifting (2.5V/3.3V operation). It delivers near-zero propagation delay (0.25 ns typical at 3.3V), 5Ω typical ON-state resistance, and supports mixed-mode signaling across 0–5V logic families in PCI, USB, and memory isolation applications.
For engineers reviewing the SN74CB3T3245DWR datasheet, SN74CB3T3245DWR pinout, SN74CB3T3245DWR application, or SN74CB3T3245DWR equivalent, key selection criteria include its 2.3–3.6V VCC range, Ioff partial-power-down capability, 5pF OFF-state capacitance, and SOIC-20 package compatibility with legacy '245 layouts.
Technical Context
The SN74CB3T3245DWR implements eight independent FET switches controlled by a single active-low OE input, enabling or disabling bidirectional A↔B signal paths. Its voltage translation tracks VCC, allowing 5V inputs to be down-shifted to 3.3V or 2.5V outputs without external components.
Each switch features undershoot clamp diodes, 5V-tolerant I/Os regardless of power state, and Ioff protection that prevents backflow current during partial power-down. The device operates across –40°C to +85°C and meets JESD 17 latch-up (>250 mA) and JESD 22 ESD standards (2000V HBM, 1000V CDM).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3V to 3.6V - Enables use in 2.5V and 3.3V systems with margin for supply variation. |
| ron (Typical) | 5Ω - Minimizes voltage drop and signal distortion under 32mA load per channel. |
| Propagation Delay | 0.25 ns at 3.3V - Supports high-speed bus switching without timing budget impact. |
| Cio(OFF) | 5 pF - Reduces capacitive loading on driven buses, preserving signal integrity. |
| Ioff Current | 10 µA max at VCC = 0 - Ensures robust isolation and prevents backfeed in powered-down subsystems. |
| ESD Rating | ±2000V HBM - Meets industrial handling requirements without additional board-level protection. |
| Operating Temp | –40°C to +85°C - Qualified for extended-temperature industrial and embedded deployments. |
Pinout & Package
SN74CB3T3245DWR uses a 20-pin SOIC (DW) package measuring 12.8 mm × 10.3 mm, compatible with standard surface-mount assembly and legacy PCB footprints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 20 | NC / VCC | Pin 1 unconnected; Pin 20 supplies core logic and switch bias - requires local 0.1µF bypass. |
| 2–9 | A1–A8 | Input/output terminals for side A - support 0–5V signaling and clamp diodes for undershoot protection. |
| 11–18 | B1–B8 | Input/output terminals for side B - electrically identical to A-side, enabling true bidirectional translation. |
| 10 | GND | Ground reference for all internal circuitry and switch channels - must be low-impedance. |
| 19 | OE | Active-low output enable - drives high-impedance state when high; ties to VCC via pullup for power-up safety. |
Key Features
| Feature | Design Value |
|---|---|
| Standard '245 pinout | Enables drop-in replacement for legacy 74-series bus switches without PCB redesign. |
| Voltage translation tracking VCC | Automatically adapts output levels to VCC (e.g., 5V→3.3V at 3.3V VCC), eliminating external level shifters. |
| 5V-tolerant I/Os (powered/unpowered) | Allows hot-plug and mixed-voltage system integration without risk of damage during power sequencing. |
| Ioff partial-power-down support | Prevents current backflow when VCC = 0, enabling safe isolation in multi-rail power architectures. |
| Bidirectional zero-delay switching | Supports full-duplex data flow with no direction control pins - ideal for shared-bus topologies. |
Applications
| PCI Interface | USB Interface |
|---|---|
Use Scenario: Isolating 3.3V USB controller from 5V peripheral logic while maintaining signal integrity during plug/unplug events. IC Role / Device Role / Timing Role: Bidirectional level-shifting bus switch enabling 5V↔3.3V translation on D+ and D− lines without added latency. Use Value: Eliminates need for discrete MOSFET translators or dual-supply buffers, reducing BOM count and layout area. | Use Scenario: Interfacing a 2.5V FPGA I/O bank to a 5V legacy PCI add-in card in industrial control backplanes. IC Role / Device Role / Timing Role: Voltage-translating bus isolator providing 5V-tolerant inputs and VCC-referenced outputs for clean signal coupling. Use Value: Maintains <1 ns propagation skew across all 8 lanes, preserving setup/hold timing margins in synchronous transfers. |
| Memory Interleaving | Bus Isolation |
Use Scenario: Sharing a common address/data bus between two memory banks operating at different voltages (e.g., 3.3V SDRAM and 2.5V SRAM). IC Role / Device Role / Timing Role: Low-capacitance bidirectional switch enabling dynamic bus arbitration with minimal loading. Use Value: 5pF OFF-state capacitance prevents signal degradation and crosstalk during inactive cycles. | Use Scenario: Protecting a microcontroller's 3.3V GPIO header from accidental 5V connection during field service or debug probing. IC Role / Device Role / Timing Role: Fail-safe isolation gate activated by OE control, blocking fault currents before damage occurs. Use Value: Ioff specification guarantees <10µA leakage at VCC = 0, preventing unintended power rail coupling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBT3245DBQR | SSOP-20 package; higher RθJA (102.4°C/W); same electrical specs. | Preferred for space-constrained boards where SOIC footprint is unavailable. | Select when board real estate is limited and thermal derating is acceptable. |
| SN74CB3T3245DGSR | VSSOP-20 package; lower RθJA (127°C/W); identical functionality and pinout. | Suitable for portable equipment requiring minimal PCB area and low weight. | Choose for handheld or battery-powered designs needing compact packaging. |
Compared with SN74CB3T3245DWR, the SSOP and VSSOP alternatives offer identical switching performance and voltage translation but differ in thermal resistance and board footprint - SOIC provides best thermal dissipation for high-density industrial layouts, while VSSOP enables miniaturization at the cost of tighter thermal margins.
Availability
SN74CB3T3245DWR is available at Aetrix Electronics and suitable for PCI interface design, USB host-peripheral bridging, and memory interleaving applications requiring stable component supply and long-term industrial lifecycle support.
Supply support for SN74CB3T3245DWR 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 for industrial, automotive, and personal electronics markets.
The SN74CB3T3245DWR belongs to TI's CB3T bus switch family, engineered for low-power, mixed-voltage system interconnect with emphasis on level translation, hot-swap safety, and minimal propagation delay in portable and infrastructure equipment.
FAQ
What is the maximum allowable I/O voltage for SN74CB3T3245DWR when VCC = 0V?
The SN74CB3T3245DWR supports 5V-tolerant I/Os regardless of VCC state. When VCC = 0V, VI/O can safely reach up to 5.5V per the Absolute Maximum Ratings table, enabled by internal clamp structures and Ioff protection. This allows the SN74CB3T3245DWR to remain safely connected to live 5V buses during system power-down sequences without damage or backfeed current.
Does SN74CB3T3245DWR require external pull-up resistors on the OE pin?
Yes - to ensure a defined high-impedance state during power-up or brownout, OE must be tied to VCC through a pull-up resistor. The minimum value depends on the driver's sink capability; TI recommends calculating based on worst-case IOH of the driving source. Without this, the SN74CB3T3245DWR may briefly enable during power transition, risking bus contention. The SN74CB3T3245DWR datasheet specifies this as a mandatory design requirement for robust operation.
Can SN74CB3T3245DWR translate 1.8V signals to 3.3V?
No - the SN74CB3T3245DWR performs only down-translation: outputs track VCC, so a 1.8V input with 3.3V VCC yields ~1.8V output, not 3.3V. It supports 0–5V inputs but cannot boost voltage. For 1.8V-to-3.3V translation, a dedicated level shifter with active pull-up (e.g., TXB0108) is required. The SN74CB3T3245DWR is optimized for 5V→3.3V and 5V/3.3V→2.5V scenarios, not upward translation.
What is the thermal resistance (RθJA) of SN74CB3T3245DWR in its SOIC package?
The SN74CB3T3245DWR in SOIC-20 (DW) package has a junction-to-ambient thermal resistance (RθJA) of 58°C/W, per TI's Thermal Information table. This is the lowest RθJA among all package variants (VSSOP: 127°C/W, SSOP: 102.4°C/W), making the SN74CB3T3245DWR particularly suitable for thermally demanding industrial applications where power dissipation must be minimized without heatsinking.
How does the Ioff feature of SN74CB3T3245DWR protect system-level power domains?
The Ioff feature in SN74CB3T3245DWR disables current flow between A and B ports when VCC = 0V, limiting leakage to ≤10 µA. This prevents back-driving of powered-down rails by active peripherals - critical in multi-voltage systems like laptops or modular PLCs. Unlike standard bus switches, the SN74CB3T3245DWR maintains isolation even with 5V present on I/Os during standby, satisfying IEC 61000-4-2 and JEDEC JESD78 reliability requirements.
SN74CB3T3245DWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CB
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Bus Switch
- Circuit:
- 8 x 1:1
- Independent Circuits:
- 1
- Current - Output High, Low:
- -
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 2.3V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74CB3T3245DWR FAQ
1.How can I place an order for SN74CB3T3245DWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CB3T3245DWR 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 SN74CB3T3245DWR reliable?
The price and inventory of SN74CB3T3245DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CB3T3245DWR is usually 5 days.
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SN74CB3T3245DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CB3T3245DWR 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 SN74CB3T3245DWR?
For technical support, including SN74CB3T3245DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CB3T3245DWR requirements.
6.How does Aetrix verify that SN74CB3T3245DWR is sourced from the original manufacturer or authorized distributors?
All SN74CB3T3245DWR 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 SN74CB3T3245DWR meets industry standards.
7.What is the process for return or replacement of SN74CB3T3245DWR?
All SN74CB3T3245DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CB3T3245DWR, 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 SN74CB3T3245DWR part is unused and in its original packaging.
Return procedure for SN74CB3T3245DWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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