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Texas Instruments SN74CB3T3245DW
- Part No.:
- SN74CB3T3245DW
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74CB3T3245DW.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,711
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Product details
Overview
SN74CB3T3245DW from Texas Instruments is an 8-bit FET bus switch with bidirectional data flow, 5V-tolerant I/Os, and VCC-referenced level shifting (2.3V–3.6V supply). It delivers near-zero propagation delay (0.25 ns typical at 3.3V), 5Ω typical ON-state resistance, and 5pF OFF-state capacitance-enabling mixed-mode interfacing between 5V TTL, 3.3V LVTTL, and 2.5V CMOS systems in portable and embedded applications.
For engineers reviewing the SN74CB3T3245DW datasheet, SN74CB3T3245DW pinout, SN74CB3T3245DW application, or SN74CB3T3245DW equivalent, key selection criteria include its 20-pin SOIC package, active-low OE control, 5V-tolerant operation during power-up/down, Ioff partial-power-down support, and compatibility with PCI, USB, and memory interleaving signal translation requirements.
Technical Context
The SN74CB3T3245DW implements eight independent FET-based analog switches with gate drive referenced to VCC, enabling output voltage translation that tracks the supply rail. Its architecture supports true bidirectional signal flow without direction control pins and maintains high-impedance isolation when OE is high.
Each switch features undershoot clamp diodes on all I/O and control inputs, operates across –40°C to +85°C, and meets JESD 17 latch-up (>250 mA) and JESD 22 ESD ratings (±2000 V HBM, ±1000 V CDM). The device is specified for partial-power-down use via Ioff, preventing backflow current when VCC = 0 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3 V to 3.6 V - Enables operation in 2.5V and 3.3V logic domains while supporting 5V-tolerant I/Os. |
| ron (Typical) | 5 Ω at VCC = 2.5V - Minimizes voltage drop and signal distortion under 24 mA load per channel. |
| Propagation Delay | 0.25 ns at 3.3V - Near-zero delay enables high-speed bus switching without timing budget impact. |
| I/O Capacitance (OFF) | 5 pF typical - Reduces capacitive loading on source and destination buses, preserving signal integrity. |
| ICC (Max) | 40 µA - Ultra-low quiescent current supports battery-powered and low-power portable equipment. |
| Operating Temperature | –40°C to +85°C - Qualified for industrial-grade embedded and communications applications. |
| ESD Rating (HBM) | ±2000 V - Robust handling in manufacturing and field environments without external protection. |
Pinout & Package
SN74CB3T3245DW is housed in a 20-pin SOIC (DW) package measuring 12.8 mm × 10.3 mm, with standard '245-type pinout and gull-wing leads suitable for through-hole and surface-mount assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | NC | No internal connection - Must be left unconnected; no routing or pull-up required. |
| 2–9 | A1–A8 | Switch input terminals - Bidirectional A-side ports; accept 0–5 V signals regardless of VCC. |
| 10 | GND | Ground reference - Primary return path for VCC and all I/O currents; requires low-impedance PCB plane. |
| 11–18 | B8–B1 | Switch output terminals - Bidirectional B-side ports; output voltage level tracks VCC (e.g., 5V→3.3V downshift). |
| 19 | OE | Active-low output enable - Driven low to connect A↔B ports; high-Z state when high; TTL/CMOS compatible. |
| 20 | VCC | Power supply - Supplies gate bias for FET switches; requires 0.1 µF bypass capacitor placed adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Mixed-mode level shifting | Supports 5V→3.3V and 5V/3.3V→2.5V translation with single VCC rail-eliminates need for dual-supply translators. |
| 5V-tolerant I/Os | Operates safely with 0–5.5 V signals on all A/B ports whether powered or unpowered-enables hot-swap and power sequencing flexibility. |
| Ioff partial-power-down | Blocks current flow when VCC = 0 V-prevents backfeeding into powered subsystems during system sleep or fault conditions. |
| Standard '245 pinout | Pin-compatible with legacy 74-series bus transceivers-simplifies drop-in replacement in existing layouts and firmware. |
| Low dynamic loading | 5 pF OFF-state capacitance and 5 Ω ron minimize reflections, crosstalk, and timing skew in high-speed parallel buses. |
Applications
| PCI Interface Signal Isolation | USB 2.0 Data Line Level Translation |
|---|---|
|
Use Scenario: Isolating legacy PCI bus segments operating at 5V from newer 3.3V peripheral controllers during board-level upgrades. IC Role / Device Role / Timing Role: Bidirectional bus switch enabling seamless 5V ↔ 3.3V data exchange without direction control or clock domain crossing logic. Use Value: Eliminates need for discrete level-shifter ICs or resistor networks, reducing BOM count and layout area while maintaining sub-nanosecond timing alignment. |
Use Scenario: Translating D+ and D− signals between a 5V-capable microcontroller and a 3.3V USB PHY in embedded host designs. IC Role / Device Role / Timing Role: Low-capacitance, low-ron analog switch providing bidirectional 5V-to-3.3V voltage translation synchronized to USB packet timing. Use Value: Preserves USB 2.0 full-speed (12 Mbps) signal integrity with <0.25 ns propagation delay and no added jitter or duty-cycle distortion. |
| Memory Interleaving Bus Switching | Low-Power Portable Equipment I/O Bridging |
|
Use Scenario: Dynamically connecting two memory banks (e.g., LPDDR2 and NOR flash) to a shared controller bus in space-constrained SoC modules. IC Role / Device Role / Timing Role: High-speed 8-bit bus switch controlled by OE to enable time-multiplexed access-no address decoding or arbitration logic needed. Use Value: Reduces interconnect complexity and PCB layer count versus multiplexer-based solutions; supports >100 MHz toggle rates with minimal skew. |
Use Scenario: Interfacing a 5V sensor interface ASIC with a 2.5V application processor in handheld medical or industrial IoT devices. IC Role / Device Role / Timing Role: Voltage-translating bus switch enabling direct connection between disparate logic families while minimizing standby current draw. Use Value: Achieves 40 µA max ICC and Ioff support-extending battery life in always-on monitoring modes without compromising signal fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3384DW | 10-bit, dual-supply (VCCA=2.3–3.6V, VCCB=3–5.5V), higher ron (7Ω typ), no Ioff | Requires separate VCC rails; lacks partial-power-down capability-unsuitable for hot-plug or asymmetric power sequencing. | Choose only if dual-voltage translation (e.g., 2.5V ↔ 5V) is required and Ioff is not critical. |
| SN74LVC245APW | Octal non-inverting transceiver, 3-state outputs, no level shifting, ron not specified, 3.3V-only operation | Cannot translate 5V inputs to lower voltages; requires external clamping or series resistors for 5V-tolerance. | Select only for same-voltage bus buffering where level shifting is handled elsewhere in the signal chain. |
Compared with SN74CB3T3245DW, SN74CBTD3384DW offers wider voltage flexibility but sacrifices Ioff and adds complexity, while SN74LVC245APW provides simpler buffering at the cost of zero level-shifting capability-making SN74CB3T3245DW uniquely suited for mixed-voltage, low-power, hot-plug-aware designs.
Availability
SN74CB3T3245DW is available at Aetrix Electronics and suitable for PCI interface isolation, USB 2.0 data line translation, and memory interleaving applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74CB3T3245DW 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 precision analog design and industrial-grade reliability.
SN74CB3T3245DW belongs to TI's CB3T family of low-voltage FET bus switches, engineered specifically for mixed-signal voltage translation and hot-plug-capable bus isolation in portable, industrial, and communications equipment.
FAQ
What is the maximum allowable I/O voltage for SN74CB3T3245DW when VCC = 0 V?
The SN74CB3T3245DW supports 5V-tolerant I/Os even when unpowered: VI/O can range from –0.5 V to 7 V regardless of VCC state. This allows safe connection to live 5V buses during power-up/down sequences and enables hot-swap functionality without risk of damage or backfeeding-critical for modular systems and field-replaceable units.
Does SN74CB3T3245DW require external pull-up resistors on the OE pin?
Yes-TI recommends tying OE to VCC via a pull-up resistor to ensure high-impedance state during power-up. The minimum resistor value depends on the driver's current-sinking capability; typical values range from 4.7 kΩ to 10 kΩ. This prevents undefined switching states and ensures deterministic bus isolation before firmware initialization.
Can SN74CB3T3245DW translate 1.8V signals to 3.3V?
No-SN74CB3T3245DW performs down-translation only: output voltage tracks VCC, so it converts higher input voltages (up to 5V) to VCC-level outputs (2.3–3.6V). It cannot boost 1.8V to 3.3V. For up-translation, a dedicated level shifter like TXS0108E or dual-supply switch (e.g., SN74AVC4T245) is required.
What is the thermal resistance (RθJA) of SN74CB3T3245DW in its SOIC package?
The SN74CB3T3245DW in the DW (SOIC-20) package has a junction-to-ambient thermal resistance (RθJA) of 58°C/W. This value assumes standard JEDEC 2-layer board conditions and confirms suitability for continuous operation at full load within industrial temperature limits without forced airflow or heatsinking.
How does the Ioff feature of SN74CB3T3245DW protect downstream circuitry?
The Ioff feature disables current flow through the FET channels when VCC = 0 V, limiting Ioff leakage to ≤10 µA per I/O. This prevents back-driving powered subsystems from unpowered sections-protecting voltage regulators, microcontrollers, and memory devices from latch-up or unintended wake-up during partial power-down modes.
SN74CB3T3245DW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CB
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- 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
SN74CB3T3245DW FAQ
1.How can I place an order for SN74CB3T3245DW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CB3T3245DW 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 SN74CB3T3245DW reliable?
The price and inventory of SN74CB3T3245DW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CB3T3245DW is usually 5 days.
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Once your SN74CB3T3245DW 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 SN74CB3T3245DW?
For technical support, including SN74CB3T3245DW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CB3T3245DW requirements.
6.How does Aetrix verify that SN74CB3T3245DW is sourced from the original manufacturer or authorized distributors?
All SN74CB3T3245DW 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 SN74CB3T3245DW meets industry standards.
7.What is the process for return or replacement of SN74CB3T3245DW?
All SN74CB3T3245DW units undergo pre-shipment inspection (PSI). If there is an issue with SN74CB3T3245DW, 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 SN74CB3T3245DW part is unused and in its original packaging.
Return procedure for SN74CB3T3245DW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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