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Texas Instruments SN74CB3T3245DBQR
- Part No.:
- SN74CB3T3245DBQR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
SN74CB3T3245DBQR.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,496
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Product details
Overview
SN74CB3T3245DBQR from Texas Instruments is an 8-bit FET bus switch with bidirectional data flow, 5Ω typical ON-state resistance, 5V-tolerant I/Os, and VCC-operated voltage translation (2.3V–3.6V). It enables level shifting between 5V TTL and 2.5V/3.3V logic in PCI and USB interfaces while maintaining near-zero propagation delay.
For engineers reviewing the SN74CB3T3245DBQR datasheet, SN74CB3T3245DBQR pinout, SN74CB3T3245DBQR application, or SN74CB3T3245DBQR equivalent, key selection criteria include mixed-mode signal support, Ioff partial-power-down capability, 5pF OFF-state I/O capacitance, and standard '245-type pin compatibility for drop-in replacement in legacy bus isolation designs.
Technical Context
The SN74CB3T3245DBQR implements eight independent FET-based transmission gates controlled by a single active-low OE input, enabling simultaneous bidirectional switching between A- and B-port I/Os. Its gate drive architecture tracks VCC to deliver output voltage translation without external biasing.
Each switch supports 0–5V signaling across all I/Os regardless of VCC (2.3V–3.6V), with undershoot clamp diodes on all inputs and guaranteed 5V tolerance during power-up/down. The device meets JESD 17 latch-up (>250mA) 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 supply variation. |
| ron (Typical) | 5Ω at VCC = 2.5V - Minimizes voltage drop and signal distortion under 24mA load per channel. |
| Cio(OFF) | 5pF typical - Reduces capacitive loading on driven buses, preserving signal integrity in high-speed routing. |
| Propagation Delay | 0.25ns at 3.3V - Near-zero delay enables use in timing-critical 5V-to-3.3V data paths without skew compensation. |
| Ioff Support | Specified for partial-power-down - Prevents backflow current when VCC = 0V, enabling hot-swap and power-gating safety. |
| ESD Rating | ±2000V HBM - Meets industrial-grade handling requirements without additional protection circuitry. |
| Operating Temp | –40°C to +85°C - Validated for extended temperature range in embedded and industrial control applications. |
Pinout & Package
SN74CB3T3245DBQR uses a 20-pin SSOP (DBQ) package measuring 8.65mm × 6mm with 0.65mm lead pitch. The package is RoHS-compliant, moisture-sensitive level 2 (260°C peak reflow, 1-year floor life), and features NIPDAU lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | NC | No internal connection - Must be left unconnected; no routing or grounding required. |
| 2–9 | A1–A8 | Input/output terminals for side A - Bidirectionally connected to B1–B8 when OE is low; tolerate 0–5V signals. |
| 10 | GND | Ground reference - Serves as return path for all internal circuitry and must be low-impedance. |
| 11–18 | B8–B1 | Input/output terminals for side B - Mirror A1–A8 functionality; enable full 8-bit bidirectional bus coupling. |
| 19 | OE | Active-low output enable - Drives entire switch array; requires pull-up to VCC for power-up high-impedance state. |
| 20 | VCC | Supply voltage input - Powers internal logic and FET gates; requires 0.1μF bypass capacitor placed adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Output voltage translation | Tracks VCC - Enables automatic down-shifting (e.g., 5V→3.3V with 3.3V VCC) without external resistors or level-shifters. |
| Mixed-mode signal operation | Supports 0.8V–5V I/O levels on all ports - Allows interoperability between 1.8V, 2.5V, 3.3V, and 5V subsystems in same design. |
| 5V-tolerant I/Os | Valid with device powered up or down - Eliminates need for power sequencing control in multi-rail systems. |
| Bidirectional zero-delay switching | No direction control pin required - Simplifies PCB layout and firmware logic versus directional translators. |
| Low ICC | 40μA maximum - Reduces quiescent power in battery-powered portable equipment and always-on interfaces. |
Applications
| PCI Interface Level Translation | USB 2.0 Data Line Isolation |
|---|---|
|
Use Scenario: Connecting a 5V PCI bus controller to a 3.3V peripheral ASIC in industrial backplane systems. IC Role / Device Role / Timing Role: Bidirectional voltage translator and bus isolator that maintains signal integrity across mixed-voltage domains. Use Value: Eliminates discrete resistor-divider networks and reduces board area by 40% versus dual-supply level shifters. |
Use Scenario: Isolating USB D+ and D− lines between a 3.3V microcontroller and legacy 5V host transceiver. IC Role / Device Role / Timing Role: Low-capacitance (5pF OFF) bus switch enabling full-speed USB 2.0 compliance without signal degradation. Use Value: Preserves rise/fall times below 2ns, meeting USB 2.0 eye diagram mask requirements at 480Mbps. |
| Memory Interleaving Control | Low-Power Portable Equipment Bus Switching |
|
Use Scenario: Dynamically routing address/data lines between two 2.5V DDR memory banks sharing a 3.3V controller. IC Role / Device Role / Timing Role: High-speed 8-bit bus switch with sub-nanosecond propagation delay for cycle-accurate memory arbitration. Use Value: Enables deterministic latency <1ns per switch transition, critical for real-time memory access timing budgets. |
Use Scenario: Power-gating unused I/O sections in handheld medical devices to extend battery life. IC Role / Device Role / Timing Role: Ioff-enabled bus isolator that blocks leakage paths during sleep mode with zero standby current draw. Use Value: Reduces system-level standby power by >95% compared to non-Ioff alternatives in portable applications. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBT3245DBQR | Higher ron (7Ω typical), no Ioff support, wider VCC range (4.5V–5.5V) | Limited to 5V-only systems; unsuitable for partial-power-down or mixed-voltage domains | Select only for cost-sensitive 5V-only designs where Ioff and level translation are unnecessary. |
| SN74LVC245APW | Direction-controlled (DIR pin), higher Cio (12pF), no 5V tolerance on I/Os | Requires external level-shifting for 5V interfacing; adds routing complexity and timing uncertainty | Prefer when unidirectional flow and 3.3V-only operation suffice, but avoid for bidirectional 5V-tolerant use cases. |
Compared with SN74CB3T3245DBQR, SN74CBT3245DBQR lacks Ioff and voltage translation, limiting its use to fixed 5V rails, while SN74LVC245APW introduces direction control overhead and fails 5V-tolerance requirements-making SN74CB3T3245DBQR uniquely suited for robust, bidirectional mixed-voltage bus isolation.
Availability
SN74CB3T3245DBQR is available at Aetrix Electronics and suitable for PCI interface level translation, USB 2.0 data line isolation, and memory interleaving control requiring stable component supply across industrial, computing, and portable electronics programs.
Supply support for SN74CB3T3245DBQR 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 and embedded processing solutions, with over 90 years of innovation in precision analog, power management, and logic ICs.
SN74CB3T3245DBQR belongs to TI's CB3T family of advanced bus switches designed specifically for low-latency, mixed-voltage signal routing in portable, industrial, and communications infrastructure applications.
FAQ
What is the maximum allowable I/O voltage for SN74CB3T3245DBQR when VCC = 0V?
SN74CB3T3245DBQR supports 0–5.5V on all I/O pins (A1–A8, B1–B8) regardless of VCC state, including full 5V tolerance during power-down. This is verified per absolute maximum ratings (VI/O = –0.5V to 7V) and enables safe hot-plug operation in multi-rail systems without risk of latch-up or damage to SN74CB3T3245DBQR.
Does SN74CB3T3245DBQR require external pull-up resistors on the OE pin?
Yes - to ensure high-impedance state during power-up or power-down, OE must be tied to VCC via a pull-up resistor. The minimum value depends on the driver's sink capability; TI recommends starting with 10kΩ and verifying timing margins. This requirement applies directly to SN74CB3T3245DBQR and is documented in Section 7.1 of the datasheet.
Can SN74CB3T3245DBQR translate 1.8V signals to 3.3V?
No - SN74CB3T3245DBQR performs down-translation only: output voltage tracks VCC, so it can shift 5V→3.3V (with 3.3V VCC) or 5V/3.3V→2.5V (with 2.5V VCC), but cannot boost 1.8V to 3.3V. This limitation is inherent to its passive FET architecture and confirmed in Section 7.3 for SN74CB3T3245DBQR.
What is the thermal resistance (RθJA) of SN74CB3T3245DBQR in its SSOP package?
The junction-to-ambient thermal resistance RθJA for SN74CB3T3245DBQR in the DBQ (SSOP-20) package is 102.4°C/W, as specified in Section 5.4. This value assumes standard JEDEC 2-layer board conditions and informs heatsink or airflow requirements when operating near maximum ICC (40μA) under worst-case ambient temperatures.
How does the Ioff feature of SN74CB3T3245DBQR protect downstream circuitry?
Ioff disables current flow through the FET channels when VCC = 0V, preventing back-driving of powered-down sections by live 5V I/Os. This protects SN74CB3T3245DBQR and connected devices from damaging current injection, satisfying JESD 17 latch-up immunity (>250mA) and enabling safe partial-power-down operation in complex systems.
SN74CB3T3245DBQR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CB
- Package/Case:
- 20-SSOP (0.154", 3.90mm 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-SSOP
SN74CB3T3245DBQR FAQ
1.How can I place an order for SN74CB3T3245DBQR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CB3T3245DBQR 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 SN74CB3T3245DBQR reliable?
The price and inventory of SN74CB3T3245DBQR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CB3T3245DBQR is usually 5 days.
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Once your SN74CB3T3245DBQR 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 SN74CB3T3245DBQR?
For technical support, including SN74CB3T3245DBQR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CB3T3245DBQR requirements.
6.How does Aetrix verify that SN74CB3T3245DBQR is sourced from the original manufacturer or authorized distributors?
All SN74CB3T3245DBQR 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 SN74CB3T3245DBQR meets industry standards.
7.What is the process for return or replacement of SN74CB3T3245DBQR?
All SN74CB3T3245DBQR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CB3T3245DBQR, 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 SN74CB3T3245DBQR part is unused and in its original packaging.
Return procedure for SN74CB3T3245DBQR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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