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Texas Instruments SN74CBT3345CDBQR
- Part No.:
- SN74CBT3345CDBQR
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 20-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
SN74CBT3345CDBQR.pdf
- Description:
- IC BUS SWITCH 8 X 1:1 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,087
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Product details
Overview
SN74CBT3345CDBQR from Texas Instruments is an 8-bit bidirectional FET bus switch IC with dual OE control, 3 Ω typical ON-state resistance (ron), near-zero propagation delay (0.15 ns at VCC = 5 V), and −2 V undershoot protection on A/B ports. It enables low-distortion signal gating in USB interfaces and memory interleaving applications operating across 0–5 V signaling levels.
For engineers reviewing the SN74CBT3345CDBQR datasheet, SN74CBT3345CDBQR pinout, SN74CBT3345CDBQR application, or SN74CBT3345CDBQR equivalent, key selection criteria include Ioff-enabled partial-power-down support, 5.5 pF typical OFF-state I/O capacitance, dual active-high/active-low enable logic, and SSOP-20 (DBQ) package compatibility with industrial temperature range (−40°C to 85°C).
Technical Context
The SN74CBT3345CDBQR implements TTL-compatible FET switching with independent high-impedance control via complementary OE inputs: OE high or OE low enables bidirectional conduction between A and B ports; both OE low and OE high disables the switch. Its undershoot-protection circuitry actively clamps A/B port voltages down to −2 V while maintaining OFF-state isolation.
Designed for mixed-voltage system interfacing, it supports data I/Os from 0 V to 5.5 V regardless of VCC (4–5.5 V), accepts TTL or 3.3/5-V CMOS control inputs, and features Ioff to prevent backflow current during partial power-down - critical for hot-swap and power-gated subsystems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4 V to 5.5 V - ensures stable operation across standard 5-V supply rails with ±10% tolerance. |
| ron (Typical) | 3 Ω - minimizes voltage drop and power loss during signal pass-through, preserving signal integrity. |
| tpd (Max) | 0.24 ns at VCC = 4 V - enables high-speed digital switching without timing skew in parallel bus architectures. |
| Cio(OFF) | 5.5 pF typical - reduces capacitive loading on driven lines, limiting signal distortion and crosstalk. |
| Undershoot Protection | −2 V on A/B ports - prevents latch-up or damage during transient negative excursions in noisy environments. |
| Ioff | 10 µA max at VCC = 0 V - blocks reverse current flow when powered down, enabling safe partial-power-down mode. |
| ICC (Max) | 3 µA - ultra-low quiescent current supports energy-efficient system design and battery-backed operation. |
Pinout & Package
SN74CBT3345CDBQR is housed in a 20-pin SSOP (Shrink Small Outline Package) with DBQ designation, 0.65 mm lead pitch, 6.6 mm × 4.5 mm body size, and 1.2 mm maximum height. The package is RoHS-compliant, moisture sensitivity level 2 (260°C peak reflow), and rated for −40°C to 85°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OE, OE | Complementary output-enable controls | OE high OR OE low activates bidirectional A↔B connection; both high/low disables switch (high-Z state). |
| A1–A8 | Input/output port A | Bidirectional data terminals tied to one side of the 8-channel FET switch array. |
| B1–B8 | Input/output port B | Bidirectional data terminals tied to the opposite side of the 8-channel FET switch array. |
| VCC | Positive supply | Provides bias for internal logic and FET channel conduction; must be 4–5.5 V. |
| GND | Ground reference | Common return path for supply and signal currents; required for proper undershoot clamp operation. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional low-ron switching | 3 Ω typical ron enables minimal insertion loss and preserves rise/fall times in high-speed digital paths. |
| Dual active-enable logic | Independent OE and OE pins allow flexible control architecture - e.g., one tied high, the other driven by processor GPIO. |
| −2 V undershoot protection | On-chip clamp circuitry maintains OFF-state integrity during negative transients, eliminating need for external diodes. |
| Ioff partial-power-down support | Prevents back-current when VCC = 0 V, enabling safe hot-plug operation and power sequencing in multi-rail systems. |
| Wide voltage I/O compatibility | 0–5.5 V data I/O range works across 0.8 V to 5 V logic families without level shifters. |
Applications
| USB Interface | Memory Interleaving |
|---|---|
Use Scenario: Isolating USB 2.0 D+ and D− lines between host controller and peripheral during suspend/resume transitions. IC Role / Device Role / Timing Role: Bidirectional signal gate controlling physical-layer connectivity with sub-nanosecond propagation delay. Use Value: Prevents signal corruption during power-state transitions while supporting full-speed 480 Mbps signaling integrity. | Use Scenario: Dynamically routing address/data lines between two DDR SDRAM banks sharing a common controller. IC Role / Device Role / Timing Role: Low-latency bus switch enabling bank-select multiplexing without adding setup/hold timing overhead. Use Value: Eliminates need for tristate buffers or complex clock-domain crossing logic in memory subsystems. |
| Bus Isolation | Low-Distortion Signal Gating |
Use Scenario: Electrically isolating legacy parallel bus segments (e.g., ISA or LPC) from modern microcontroller peripherals. IC Role / Device Role / Timing Role: High-impedance break-before-make switch preventing contention during bus arbitration or firmware updates. Use Value: Enables safe firmware field upgrades without risk of bus lockup or voltage conflict between powered/unpowered domains. | Use Scenario: Enabling/disabling analog sensor signals (e.g., thermocouple or RTD front-end outputs) in precision measurement systems. IC Role / Device Role / Timing Role: Analog-capable FET switch providing low-charge-injection, low-leakage signal path control. Use Value: Maintains DC accuracy and low noise floor (<5.5 pF Cio(OFF)) during signal path selection in 16-bit+ ADC systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74CBTD3305PWR | 5-V only operation (no 4-V min); higher ron (5 Ω typ); no undershoot protection | Lacks −2 V clamp; unsuitable for noisy industrial environments requiring robust transient immunity | Choose when cost is primary constraint and undershoot events are absent. |
| SN74LVC1G3157DCKR | Single-channel; 3.3-V only (1.65–5.5 V); ron = 5 Ω typ; no dual-OE control | Requires eight discrete units for 8-bit function; lacks complementary enable logic and undershoot protection | Use only for point-to-point signal gating where space permits replication and control simplicity is preferred. |
Compared with SN74CBT3345CDBQR, SN74CBTD3305PWR trades transient robustness for lower cost, while SN74LVC1G3157DCKR sacrifices integration density and control flexibility for broader voltage range - neither matches the combination of 8-bit bidirectional switching, dual-OE, −2 V protection, and 3 Ω ron in a single SSOP-20 package.
Availability
SN74CBT3345CDBQR is available at Aetrix Electronics and suitable for USB interface design, memory interleaving systems, and bus isolation circuits requiring stable component supply, long-term lifecycle support, and guaranteed RoHS compliance.
Supply support for SN74CBT3345CDBQR 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 electronic components.
The SN74CBT3345CDBQR belongs to TI's CBT (Crossbar Bus Transceiver) family, engineered for high-speed, low-distortion digital signal routing in mixed-voltage computing and communications infrastructure.
FAQ
What is the maximum undershoot voltage the SN74CBT3345CDBQR can withstand on its A and B ports?
The SN74CBT3345CDBQR provides active undershoot protection up to −2 V on both A and B ports, verified per test conditions in the official datasheet (SCDS129A). This protection remains effective even when the device is unpowered, ensuring robustness against negative transients in electrically noisy environments. The SN74CBT3345CDBQR achieves this via integrated clamp circuitry that holds the switch in the OFF state during undershoot events.
Does the SN74CBT3345CDBQR support partial-power-down operation, and how is it implemented?
Yes, the SN74CBT3345CDBQR supports partial-power-down operation through its Ioff feature, which limits reverse current to 10 µA maximum when VCC = 0 V. This allows the device to safely isolate powered and unpowered sections of a system, such as during hot-swap or sleep-mode transitions. The SN74CBT3345CDBQR maintains high-impedance isolation between A and B ports under these conditions, preventing damaging backflow current into powered domains.
What is the recommended power-up sequence for reliable operation of the SN74CBT3345CDBQR?
To ensure high-impedance state during power-up, OE should be tied to VCC via a pull-up resistor and OE to GND via a pull-down resistor; minimum resistor values depend on driver strength. This prevents undefined switching states before VCC stabilizes. The SN74CBT3345CDBQR requires no special sequencing between VCC and I/O voltage rails, as its data I/Os support 0–5.5 V regardless of VCC level - a key advantage for mixed-voltage system integration.
Can the SN74CBT3345CDBQR be used for analog signal switching, and what parameters support that use case?
Yes, the SN74CBT3345CDBQR is qualified for analog signal switching due to its low ON-state resistance (3 Ω typical), low OFF-state capacitance (5.5 pF), and flat ron vs. voltage profile across 0–5 V. These characteristics minimize signal attenuation, charge injection, and distortion - making it suitable for precision analog paths like sensor multiplexing or audio routing. The SN74CBT3345CDBQR has been validated in low-distortion signal gating applications per its official datasheet.
What package type and footprint does the SN74CBT3345CDBQR use, and are PCB layout guidelines available?
The SN74CBT3345CDBQR uses the SSOP-20 (DBQ) package: 6.6 mm × 4.5 mm body, 0.65 mm lead pitch, 1.2 mm max height, with pin 1 quadrant Q1 orientation in tape-and-reel. TI provides verified board layout, land pattern, and stencil design files for this package - including solder mask defined pads and 0.125 mm stencil recommendations - all accessible via ti.com/package/DBQ. The SN74CBT3345CDBQR's compact footprint supports high-density routing in space-constrained embedded designs.
SN74CBT3345CDBQR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74CBT
- 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74CBT3345CDBQR FAQ
1.How can I place an order for SN74CBT3345CDBQR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74CBT3345CDBQR 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 SN74CBT3345CDBQR reliable?
The price and inventory of SN74CBT3345CDBQR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CBT3345CDBQR is usually 5 days.
3.What payment methods are accepted for SN74CBT3345CDBQR?
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4.How is shipping managed for SN74CBT3345CDBQR?
SN74CBT3345CDBQR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74CBT3345CDBQR 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 SN74CBT3345CDBQR?
For technical support, including SN74CBT3345CDBQR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CBT3345CDBQR requirements.
6.How does Aetrix verify that SN74CBT3345CDBQR is sourced from the original manufacturer or authorized distributors?
All SN74CBT3345CDBQR 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 SN74CBT3345CDBQR meets industry standards.
7.What is the process for return or replacement of SN74CBT3345CDBQR?
All SN74CBT3345CDBQR units undergo pre-shipment inspection (PSI). If there is an issue with SN74CBT3345CDBQR, 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 SN74CBT3345CDBQR part is unused and in its original packaging.
Return procedure for SN74CBT3345CDBQR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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