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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Texas Instruments SN74CB3Q3305PWG4

Name: SN74CB3Q3305PWG4
Brand: Texas Instruments
SKU: SN74CB3Q3305PWG4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74CB3Q3305PWG4

Manufacturer:: Texas Instruments

Category:: Signal Switches, Multiplexers, Decoders

Package:: 8-TSSOP (0.173", 4.40mm Width)

Datasheet:: SN74CB3Q3305PWG4.pdf

Description:: IC BUS SWITCH 1 X 1:1 8TSSOP

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Product details

Overview

SN74CB3Q3305 from Texas Instruments is a dual 1-bit FET bus switch optimized for high-bandwidth, level-translating signal routing in mixed-voltage systems. It provides bidirectional data flow with 3 Ω typical ON-state resistance, 500 MHz bandwidth support, and 5-V tolerant I/Os while powered from 2.3 V to 3.6 V - enabling use in USB interface isolation and optical networking backplanes.

For engineers reviewing the SN74CB3Q3305 datasheet, SN74CB3Q3305 pinout, SN74CB3Q3305 application, or SN74CB3Q3305 equivalent, key selection criteria include its flat r_on over voltage/temperature, I_off-enabled partial-power-down protection, low 3.5 pF OFF-state capacitance, and dual independent OE control for channel-level switching in broadband communications infrastructure.

Technical Context

The SN74CB3Q3305 implements two independent FET-based analog switches, each controlled by dedicated OE inputs (1OE, 2OE), supporting true bidirectional signal routing without direction pins. Its internal charge pump elevates gate voltage to maintain low and flat ON-state resistance across the full 2.3–3.6 V V_CC range and –40°C to 85°C operating temperature.

Each switch supports 0–5 V signaling on I/O ports regardless of V_CC (e.g., 0–5 V with 3.3 V V_CC), enabled by robust 5-V-tolerant I/O structures and undershoot clamp diodes. The device achieves near-zero propagation delay (<0.15 ns) and supports up to 20 MHz OE toggle frequency, making it suitable for high-speed serial link isolation and hot-swap-capable backplane interfaces.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Range	2.3 V to 3.6 V - enables operation in both 2.5-V and 3.3-V system domains with margin
r_on (typ)	3 Ω - ensures minimal insertion loss and signal integrity for high-frequency signals up to 500 MHz
C_io(OFF) (typ)	3.5 pF - reduces capacitive loading on buses, preserving edge rates and minimizing crosstalk
I_off	1 µA at V_CC = 0 V - prevents backflow current during partial power-down, protecting upstream/downstream circuitry
Propagation Delay	0.15 ns max at 3.3 V - supports sub-nanosecond timing-critical applications like PCIe Gen1/2 lane isolation
OE Toggle Frequency	20 MHz max - allows dynamic channel enable/disable in real-time protocol-aware switching
I/O Voltage Range	0 V to 5.5 V - enables seamless interfacing between 1.2 V, 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains

Pinout & Package

SN74CB3Q3305 is available in TSSOP-8 (PW) and VSSOP-8 (DCU) packages. Both are 8-pin surface-mount packages with identical pinout and thermal performance characteristics per JEDEC MO-153 and MO-178 standards.

Pin/Terminal	Circuit Role	Design Meaning
1OE	Active-high enable for Channel 1	Controls connection between 1A and 1B; high = ON (low-Z path), low = OFF (high-Z isolation)
1A, 1B	Bidirectional data I/O ports for Channel 1	Interchangeable signal paths; no directionality - supports voltage translation in either direction
2OE	Active-high enable for Channel 2	Independent control of second switch; enables time-multiplexed or parallel dual-channel routing
2A, 2B	Bidirectional data I/O ports for Channel 2	Electrically isolated from Channel 1; supports separate voltage domain bridging
GND	Power ground reference	Common return for all internal circuitry and I/O clamp diodes; must be low-inductance connection
V_CC	Positive supply input	Powers internal charge pump and control logic; bypass capacitor required per TI layout guidelines

Key Features

Feature	Design Value
Charge-pump-enhanced FET switch	Maintains flat 3–8 Ω r_on across full V_CC (2.3–3.6 V) and temperature range, eliminating signal attenuation drift
5-V tolerant I/O with V_CC = 0 V	Enables safe hot-insertion and partial-power-down operation without damaging connected 5-V peripherals
Independent dual-channel OE control	Allows selective isolation of individual data lanes (e.g., USB D+/D− or PCIe TX/RX pairs) without affecting adjacent channels
Low 3.5 pF OFF-state capacitance	Minimizes stub effects and reflections on high-speed traces, critical for maintaining >1 GHz signal integrity margins
Undershoot clamp diodes on all I/O and control pins	Protects against negative transients down to –1.8 V, meeting robustness requirements for industrial and telecom environments

Applications

USB Interface Isolation	Optical Networking Backplane
Use Scenario: Isolating USB 2.0 D+ and D− lines between a 3.3-V host controller and 5-V peripheral during hot-plug events. IC Role / Device Role / Timing Role: Dual-channel bidirectional bus switch providing level translation and power-domain decoupling with <0.15 ns propagation delay. Use Value: Prevents backfeed current into powered-down host while maintaining signal fidelity up to 480 Mbps via 3 Ω r_on and 3.5 pF C_io(OFF).	Use Scenario: Routing differential clock or data signals between 2.5-V FPGA transceivers and 3.3-V SFP+ module interfaces in EPON line cards. IC Role / Device Role / Timing Role: High-bandwidth analog switch enabling 0–5 V signal pass-through with flat impedance profile across temperature. Use Value: Eliminates need for discrete level shifters or resistive terminations, reducing BOM count and preserving rise/fall times for 1.25 Gbps serial links.
WiMAX Baseband Signal Routing	IP Phone Audio/Data Multiplexing
Use Scenario: Dynamically connecting baseband I/Q signals between 1.8-V ADC/DAC and 3.3-V RF front-end in WiMAX subscriber units. IC Role / Device Role / Timing Role: Low-capacitance, bidirectional switch supporting 500 MHz bandwidth with independent channel enables. Use Value: Enables software-configurable signal path selection without degrading SNR or introducing group delay variation across channels.	Use Scenario: Sharing a single 3.3-V Ethernet PHY interface between VoIP processor and auxiliary audio codec in compact IP phone PCBs. IC Role / Device Role / Timing Role: Dual 1-bit bus switch isolating data lanes during codec initialization or firmware update sequences. Use Value: Prevents bus contention and latch-up risk during concurrent access, leveraging I_off protection when one subsystem powers down.

USB Interface Isolation

Optical Networking Backplane

Use Scenario: Isolating USB 2.0 D+ and D− lines between a 3.3-V host controller and 5-V peripheral during hot-plug events.

IC Role / Device Role / Timing Role: Dual-channel bidirectional bus switch providing level translation and power-domain decoupling with <0.15 ns propagation delay.

Use Value: Prevents backfeed current into powered-down host while maintaining signal fidelity up to 480 Mbps via 3 Ω r_on and 3.5 pF C_io(OFF).

Use Scenario: Routing differential clock or data signals between 2.5-V FPGA transceivers and 3.3-V SFP+ module interfaces in EPON line cards.

IC Role / Device Role / Timing Role: High-bandwidth analog switch enabling 0–5 V signal pass-through with flat impedance profile across temperature.

Use Value: Eliminates need for discrete level shifters or resistive terminations, reducing BOM count and preserving rise/fall times for 1.25 Gbps serial links.

WiMAX Baseband Signal Routing

IP Phone Audio/Data Multiplexing

Use Scenario: Dynamically connecting baseband I/Q signals between 1.8-V ADC/DAC and 3.3-V RF front-end in WiMAX subscriber units.

IC Role / Device Role / Timing Role: Low-capacitance, bidirectional switch supporting 500 MHz bandwidth with independent channel enables.

Use Value: Enables software-configurable signal path selection without degrading SNR or introducing group delay variation across channels.

Use Scenario: Sharing a single 3.3-V Ethernet PHY interface between VoIP processor and auxiliary audio codec in compact IP phone PCBs.

IC Role / Device Role / Timing Role: Dual 1-bit bus switch isolating data lanes during codec initialization or firmware update sequences.

Use Value: Prevents bus contention and latch-up risk during concurrent access, leveraging I_off protection when one subsystem powers down.

Equivalent & Alternatives

The following parts are listed as comparable options for similar FET bus switch applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74CBT3305CPWRE4	Lower bandwidth (200 MHz), higher r_on (7 Ω typ), no charge pump - consumes less quiescent current (0.1 mA)	Suitable for lower-speed industrial I/O expansion where power efficiency outweighs speed	Select when 500 MHz bandwidth and flat r_on are not required; verify timing margins at target data rate
TS3USB30E	Dedicated USB 2.0 switch with integrated ESD protection (8-kV HBM), fixed 3.3-V only operation, no I_off support	Optimized for USB-specific compliance (eye diagram, jitter), lacks multi-voltage flexibility	Prefer for USB-native designs requiring certified ESD robustness; avoid if mixed-voltage or partial-power-down is needed

Compared with SN74CB3Q3305, SN74CBT3305CPWRE4 trades bandwidth and r_on flatness for lower ICC, while TS3USB30E adds USB-specific features but sacrifices voltage flexibility and I_off safety - making SN74CB3Q3305 the optimal choice for general-purpose, high-fidelity, mixed-voltage signal routing.

Availability

SN74CB3Q3305 is available at Aetrix Electronics and suitable for optical networking backplanes, USB interface isolation, and WiMAX baseband routing requiring stable component supply across extended product lifecycles.

Supply support for SN74CB3Q3305 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 company specializing in analog and embedded processing technologies, with leadership in signal integrity, power management, and high-speed interface solutions.

The SN74CB3Q3305 belongs to TI's CB3Q family of charge-pump-enhanced FET bus switches, designed specifically for high-bandwidth, low-distortion signal routing in broadband communications, optical networking, and data-intensive computing systems.

FAQ

What is the maximum signal bandwidth supported by the SN74CB3Q3305?

The SN74CB3Q3305 supports up to 500 MHz signal bandwidth, verified under typical operating conditions (V_CC = 3.3 V, T_A = 25°C). This capability stems from its low 3 Ω typical ON-state resistance and 3.5 pF OFF-state capacitance, which jointly preserve signal integrity for high-speed serial protocols including USB 2.0 and EPON physical layers. Bandwidth may decrease with increased trace capacitance or reduced V_CC.

Does the SN74CB3Q3305 support level translation between different voltage domains?

Yes, the SN74CB3Q3305 supports bidirectional level translation: it accepts 0–5 V signals on its I/O ports while powered from 2.3–3.6 V V_CC. For example, with 3.3 V V_CC, it passes 0–5 V signals between 5-V peripherals and 3.3-V controllers. This is enabled by 5-V-tolerant I/O structures and internal charge-pump biasing - a core feature confirmed in the SN74CB3Q3305 datasheet Section 8.3.

How does the SN74CB3Q3305 handle partial power-down scenarios?

The SN74CB3Q3305 implements I_off circuitry that limits current backflow to 1 µA when V_CC = 0 V, protecting connected devices during hot-swap or partial-power-down. When powered off, all I/O ports enter high-impedance isolation - a behavior validated in Section 6.5 Electrical Characteristics and Section 8.4 Functional Modes of the SN74CB3Q3305 datasheet.

What package options are available for the SN74CB3Q3305?

The SN74CB3Q3305 is offered in two RoHS-compliant surface-mount packages: TSSOP-8 (PW, 3.00 mm × 6.10 mm) and VSSOP-8 (DCU, 2.00 mm × 3.10 mm). Both share identical pinout and electrical specifications. Active orderable variants include SN74CB3Q3305PWRG4 (TSSOP) and SN74CB3Q3305DCUR (VSSOP), with MSL Level-1 rating and NIPDAU or Sn lead finish.

Can the SN74CB3Q3305 be used for USB 2.0 signal switching?

Yes, the SN74CB3Q3305 is suitable for USB 2.0 signal switching due to its 500 MHz bandwidth, low 3.5 pF OFF-state capacitance, and 3 Ω r_on, which preserve signal eye diagrams and minimize jitter. It supports 0–3.3 V signaling on D+ and D− lines with 3.3 V V_CC, and its I_off protection safeguards against hot-plug transients - all confirmed in SN74CB3Q3305 Application Section 9.2 and Switching Characteristics Table 6.6.

SN74CB3Q3305PWG4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74CB

Package/Case:: 8-TSSOP (0.173", 4.40mm Width)

Packaging:: Tube

Product Status:: Discontinued at Digi-Key

Type:: Bus Switch

Circuit:: 1 x 1:1

Independent Circuits:: 2

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:: 8-TSSOP

SN74CB3Q3305PWG4 FAQ

1.How can I place an order for SN74CB3Q3305PWG4 through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74CB3Q3305PWG4 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

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The price and inventory of SN74CB3Q3305PWG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74CB3Q3305PWG4 is usually 5 days.

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SN74CB3Q3305PWG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74CB3Q3305PWG4 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 SN74CB3Q3305PWG4?

For technical support, including SN74CB3Q3305PWG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74CB3Q3305PWG4 requirements.

6.How does Aetrix verify that SN74CB3Q3305PWG4 is sourced from the original manufacturer or authorized distributors?

All SN74CB3Q3305PWG4 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 SN74CB3Q3305PWG4 meets industry standards.

7.What is the process for return or replacement of SN74CB3Q3305PWG4?

All SN74CB3Q3305PWG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74CB3Q3305PWG4, 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 SN74CB3Q3305PWG4 part is unused and in its original packaging.

Return procedure for SN74CB3Q3305PWG4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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