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Texas Instruments SN74CB3T3245PW
- Part No.:
- SN74CB3T3245PW
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74CB3T3245PW.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,211
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Product details
Overview
SN74CB3T3245PW from Texas Instruments is an 8-bit FET bus switch with bidirectional data flow, 5V-tolerant I/Os, and VCC-tracked voltage translation for mixed-mode level shifting between 2.5V/3.3V domains and 5V signals. It features 5Ω typical ON-state resistance, 5pF OFF-state I/O capacitance, and operates from 2.3V to 3.6V supply - deployed in USB interface isolation and PCI bus segmentation.
For engineers reviewing the SN74CB3T3245PW datasheet, SN74CB3T3245PW pinout, SN74CB3T3245PW application, or SN74CB3T3245PW equivalent, key selection criteria include its 5V-tolerant I/O behavior during power-up/down, near-zero propagation delay (0.25 ns at 3.3V), Ioff partial-power-down support, standard '245 pinout compatibility, and TSSOP-20 package footprint.
Technical Context
The SN74CB3T3245PW implements eight independent FET-based bilateral switches controlled by a single active-low OE input, enabling or disabling bidirectional signal paths between A and B ports. Its gate drive architecture ensures output voltage follows VCC, supporting down-translation (e.g., 5V→3.3V with VCC=3.3V or 5V/3.3V→2.5V with VCC=2.5V).
Each switch exhibits low ron (5Ω typ) and minimal parasitic capacitance (Cio(OFF) = 5pF typ), delivering sub-nanosecond propagation delay and low capacitive loading. The device integrates undershoot clamp diodes on all I/O and control pins and meets JESD 17 latch-up (>250 mA) and JESD 22 ESD ratings (±2000V HBM, ±1000V CDM).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3V to 3.6V - enables operation in 2.5V and 3.3V systems with margin for rail tolerance |
| ron (ON-state Resistance) | 5Ω typical - minimizes voltage drop and power loss under 64mA channel current |
| Cio(OFF) | 5pF typical - reduces capacitive loading on isolated buses during switch-off state |
| Propagation Delay (tpd) | 0.25ns at 3.3V - supports high-speed digital interfaces without timing penalty |
| Ioff Current | 10µA max at VCC = 0V - prevents backflow current during partial power-down |
| IO Max per Channel | ±128mA - sustains robust signal integrity across logic families driving heavy loads |
| ESD Rating (HBM) | ±2000V - meets Class II requirements for handling in automated assembly |
Pinout & Package
TSSOP-20 (PW) package: 6.5mm × 6.4mm body, 0.65mm pitch, surface-mount, lead-free (NiPdAu), MSL Level-1 (unlimited reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | NC | No internal connection - must be left unconnected or tied to GND/VCC per layout best practice |
| 2–9 | A1–A8 | Input/output terminals of port A - bidirectionally connected to B1–B8 when OE is low |
| 10 | GND | Power ground reference - required for stable switching threshold and ESD path |
| 11–18 | B8–B1 | Input/output terminals of port B - mirror A-port functionality with identical voltage tolerance |
| 19 | OE | Active-low output enable - asserts high-impedance state between A/B ports when high |
| 20 | VCC | Supply voltage input - powers internal FET gates and defines output voltage translation level |
Key Features
| Feature | Design Value |
|---|---|
| 5V-tolerant I/Os | Operates safely with 0–5.5V signals regardless of VCC state (powered up/down), eliminating external clamping |
| Mixed-mode level shifting | Translates 5V inputs to 3.3V outputs (VCC=3.3V) or 5V/3.3V inputs to 2.5V outputs (VCC=2.5V) without external components |
| Ioff partial-power-down | Blocks current backflow when VCC = 0V, enabling hot-swap and multi-rail system partitioning |
| Standard '245 pinout | Pin-compatible with industry-standard octal bus transceivers, simplifying PCB reuse and migration |
| Low ICC | 40µA maximum supply current - suitable for battery-powered portable equipment and always-on subsystems |
Applications
| USB Interface Isolation | PCI Bus Segmentation |
|---|---|
Use Scenario: Isolating 3.3V USB PHY from 5V host controller while maintaining signal integrity and ESD robustness. IC Role / Device Role / Timing Role: Bidirectional level-shifting bus switch enabling protocol-compliant data transfer across voltage domains. Use Value: Eliminates need for discrete level translators or resistive pull-ups, reducing BOM count and board space. |
Use Scenario: Segmenting legacy PCI slots to prevent ground loops and noise coupling between add-in cards and motherboard. IC Role / Device Role / Timing Role: High-speed, low-latency isolation element placed between PCI address/data lines and peripheral logic. Use Value: Maintains <0.25ns propagation delay to preserve PCI timing margins while providing 5V-tolerant fault containment. |
| Memory Interleaving Control | Bus Isolation in Portable Systems |
Use Scenario: Enabling dynamic routing of shared memory address/data lines between dual-core processors operating at different voltages. IC Role / Device Role / Timing Role: Voltage-agnostic bidirectional switch synchronizing access to common SDRAM banks. Use Value: Supports seamless 2.5V↔3.3V interoperability without timing skew or level-conversion latency. |
Use Scenario: Power-gating unused peripherals (e.g., SD card, display interface) in handheld devices to extend battery life. IC Role / Device Role / Timing Role: Low-leakage isolation gate activated via system PMIC-controlled OE signal. Use Value: Achieves <10µA off-state current (Ioff), minimizing standby power drain while preserving signal path integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar FET bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBT3245PW | Higher ron (7Ω typ), no Ioff support, 3.3V-only VCC range (3.0–3.6V) | Lacks partial-power-down capability and 2.5V operation - unsuitable for mixed-voltage hot-swap designs | Select only if design uses fixed 3.3V rails and does not require Ioff or sub-3.0V operation |
| SN74LVC245APW | Direction-controlled (non-bidirectional), higher ICC (max 100µA), no 5V-tolerant I/Os (max VI = VCC+0.3V) | Requires direction pin management and external level shifters for 5V interfacing - increases complexity | Prefer only when strict unidirectional data flow and lower cost outweigh need for simplicity and voltage flexibility |
Compared with SN74CB3T3245PW, SN74CBT3245PW offers lower cost but sacrifices Ioff and 2.5V support; SN74LVC245APW provides higher drive strength but requires additional circuitry for 5V tolerance and bidirectional use - making SN74CB3T3245PW optimal for compact, mixed-voltage, low-power isolation.
Availability
SN74CB3T3245PW is available at Aetrix Electronics and suitable for USB interface isolation, PCI bus segmentation, and memory interleaving requiring stable component supply and long-term industrial availability.
Supply support for SN74CB3T3245PW 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 high-reliability silicon solutions.
The SN74CB3T3245PW belongs to TI's CB3T family of advanced bus switches, engineered specifically for low-latency, voltage-flexible signal routing in portable, industrial, and communications equipment.
FAQ
What is the maximum allowable input voltage on the I/O pins of the SN74CB3T3245PW?
The SN74CB3T3245PW supports 0V to 5.5V on all data I/O pins regardless of VCC state - including when powered down - due to integrated 5V-tolerant protection. This allows safe interfacing with 5V TTL, LVTTL, and CMOS logic without external clamping diodes or level shifters. Absolute maximum rating is 7V, but operation above 5.5V violates recommended conditions.
Does the SN74CB3T3245PW support true bidirectional signal flow without direction control?
Yes, the SN74CB3T3245PW enables fully bidirectional data transfer between A and B ports with no direction pin required. When OE is low, each switch conducts equally in both directions - verified by symmetric ron (5Ω typ) and matched Cio(ON)/Cio(OFF) values. This eliminates timing asymmetry and simplifies PCB routing compared to directional transceivers like the SN74LVC245APW.
Can the SN74CB3T3245PW operate at 2.5V VCC while interfacing with 5V inputs?
Yes, the SN74CB3T3245PW is explicitly rated for 2.5V VCC operation with 5V-tolerant inputs. At VCC = 2.5V, it translates 5V or 3.3V inputs down to ~2.5V outputs - confirmed in the datasheet's mixed-mode operation section and Figure 7-1 DC voltage translation curves. Output voltage tracks VCC, ensuring compatibility with 2.5V logic thresholds.
What is the purpose of the NC pin (Pin 1) on the SN74CB3T3245PW?
Pin 1 of the SN74CB3T3245PW is a no-connect (NC) terminal with no internal connection. It must remain unconnected - neither tied to VCC nor GND - to avoid unintended coupling or mechanical stress on the bond wire. TI's package drawings and pin function table confirm this is a deliberate floating pad for die attach or thermal relief, not a test point or reserved function.
How does the Ioff feature of the SN74CB3T3245PW protect systems during partial power-down?
The Ioff feature limits current to ≤10µA when VCC = 0V and any I/O is biased to 0–5.5V, preventing damaging backflow through powered-down sections. This enables safe hot-plug operation and modular power sequencing in multi-rail systems. Unlike passive switches, SN74CB3T3245PW maintains isolation even with mismatched supply states - a requirement validated per JESD 78.
SN74CB3T3245PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CB
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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:
- 2.3V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
SN74CB3T3245PW FAQ
1.How can I place an order for SN74CB3T3245PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CB3T3245PW 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 SN74CB3T3245PW reliable?
The price and inventory of SN74CB3T3245PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CB3T3245PW is usually 5 days.
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Once your SN74CB3T3245PW 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 SN74CB3T3245PW?
For technical support, including SN74CB3T3245PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CB3T3245PW requirements.
6.How does Aetrix verify that SN74CB3T3245PW is sourced from the original manufacturer or authorized distributors?
All SN74CB3T3245PW 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 SN74CB3T3245PW meets industry standards.
7.What is the process for return or replacement of SN74CB3T3245PW?
All SN74CB3T3245PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74CB3T3245PW, 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 SN74CB3T3245PW part is unused and in its original packaging.
Return procedure for SN74CB3T3245PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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