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SN74CB3Q3251

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3.3-V, 8:1, 1-channel general-purpose FET bus switch

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Data sheet

SN74CB3Q3251

ACTIVE
Data sheet Order now

Product details

Protocols Analog Configuration 8:1 Number of channels 1 Bandwidth (MHz) 500 Ron (typ) (mΩ) 3500 Input/output voltage (min) (V) 0 Input/output voltage (max) (V) 5.5 Supply current (typ) (µA) 600 Operating temperature range (°C) -40 to 85 ESD CDM (kV) 1 Input/output continuous current (max) (mA) 64 COFF (typ) (pF) 3.5 CON (typ) (pF) 15 OFF-state leakage current (max) (µA) 1 Ron (max) (mΩ) 11000 VIH (min) (V) 1.7 VIL (max) (V) 0.8 Rating Catalog
Protocols Analog Configuration 8:1 Number of channels 1 Bandwidth (MHz) 500 Ron (typ) (mΩ) 3500 Input/output voltage (min) (V) 0 Input/output voltage (max) (V) 5.5 Supply current (typ) (µA) 600 Operating temperature range (°C) -40 to 85 ESD CDM (kV) 1 Input/output continuous current (max) (mA) 64 COFF (typ) (pF) 3.5 CON (typ) (pF) 15 OFF-state leakage current (max) (µA) 1 Ron (max) (mΩ) 11000 VIH (min) (V) 1.7 VIL (max) (V) 0.8 Rating Catalog
TSSOP (PW) 16 32 mm² (5 mm × 6.4 mm) SSOP (DBQ) 16 29.4 mm² (4.9 mm × 6 mm) TVSOP (DGV) 16 23.04 mm² (3.6 mm × 6.4 mm) VQFN (RGY) 16 14 mm² (4 mm × 3.5 mm)
  • High-bandwidth data path (up to 500MHz)
  • Equivalent to IDTQS3VH251 device
  • 5V tolerant I/Os with device powered up or powered down
  • Low and flat ON-state resistance (ron) characteristics over operating range (ron = 4Ω Typ)
  • Rail-to-rail switching on data I/O ports
    • 0 to 5V switching with 3.3V VCC
    • 0 to 3.3V switching with 2.5V VCC
  • Bidirectional data flow with near-zero propagation delay
  • Low input/output capacitance minimizes loading and signal distortion (Cio(OFF) = 3.5 pF Typ)
  • Fast switching frequency (fOE or fS = 20 MHz Max). For additional information regarding the performance characteristics of the CB3Q family, refer to the TI application note, CBT-C, CB3T, and CB3Q Signal-Switch Families.
  • Data and controlinputs provide undershoot clamp diodes
  • Low power consumption (ICC = 1mA Typ)
  • VCC operating range from 2.3V to 3.6V
  • Data I/Os support 0 to 5V signaling levels (0.8V, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V)
  • Control inputs can be driven by TTL or 5V/3.3V CMOS outputs
  • Ioff supports partial-power-down mode operation
  • Latch-Up performance exceeds 100mA per JESD 78, class II
  • ESD performance tested per JESD 22
    • 2000V human-body model (A114B, Class II)
    • 1000V charged-device model (C101)
  • Supports both digital and analog applications: PCI interface, differential signal interface, memory interleaving, bus isolation, low-distortion signal gating
  • High-bandwidth data path (up to 500MHz)
  • Equivalent to IDTQS3VH251 device
  • 5V tolerant I/Os with device powered up or powered down
  • Low and flat ON-state resistance (ron) characteristics over operating range (ron = 4Ω Typ)
  • Rail-to-rail switching on data I/O ports
    • 0 to 5V switching with 3.3V VCC
    • 0 to 3.3V switching with 2.5V VCC
  • Bidirectional data flow with near-zero propagation delay
  • Low input/output capacitance minimizes loading and signal distortion (Cio(OFF) = 3.5 pF Typ)
  • Fast switching frequency (fOE or fS = 20 MHz Max). For additional information regarding the performance characteristics of the CB3Q family, refer to the TI application note, CBT-C, CB3T, and CB3Q Signal-Switch Families.
  • Data and controlinputs provide undershoot clamp diodes
  • Low power consumption (ICC = 1mA Typ)
  • VCC operating range from 2.3V to 3.6V
  • Data I/Os support 0 to 5V signaling levels (0.8V, 1.2V, 1.5V, 1.8V, 2.5V, 3.3V, 5V)
  • Control inputs can be driven by TTL or 5V/3.3V CMOS outputs
  • Ioff supports partial-power-down mode operation
  • Latch-Up performance exceeds 100mA per JESD 78, class II
  • ESD performance tested per JESD 22
    • 2000V human-body model (A114B, Class II)
    • 1000V charged-device model (C101)
  • Supports both digital and analog applications: PCI interface, differential signal interface, memory interleaving, bus isolation, low-distortion signal gating

The SN74CB3Q3251 is a high-bandwidth FET bus switch utilizing a charge pump to elevate the gate voltage of the pass transistor, providing a low and flat ON-state resistance (ron). The low and flat ON-state resistance allows for minimal propagation delay and supports rail-to-rail switching on the data input/output (I/O) ports. The device also features low data I/O capacitance to minimize capacitive loading and signal distortion on the data bus. Specifically designed to support high-bandwidth applications, the SN74CB3Q3251 provides an optimized interface solution ideally suited for broadband communications, networking, and data-intensive computing systems.

The SN74CB3Q3251 is a 1-of-8 multiplexer/demultiplexer with a single output-enable ( OE) input. The select (S0, S1, S2) inputs control the data path of the multiplexer/demultiplexer. When OE is low, the multiplexer/demultiplexer is enabled, and the A port is connected to the B port, allowing bidirectional data flow between ports. When OE is high, the multiplexer/demultiplexer is disabled, and a high-impedance state exists between the A and B ports.

This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry prevents damaging current backflow through the device when it is powered down. The device has isolation during power off.

To ensure the high-impedance state during power up or power down, OE must be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.

The SN74CB3Q3251 is a high-bandwidth FET bus switch utilizing a charge pump to elevate the gate voltage of the pass transistor, providing a low and flat ON-state resistance (ron). The low and flat ON-state resistance allows for minimal propagation delay and supports rail-to-rail switching on the data input/output (I/O) ports. The device also features low data I/O capacitance to minimize capacitive loading and signal distortion on the data bus. Specifically designed to support high-bandwidth applications, the SN74CB3Q3251 provides an optimized interface solution ideally suited for broadband communications, networking, and data-intensive computing systems.

The SN74CB3Q3251 is a 1-of-8 multiplexer/demultiplexer with a single output-enable ( OE) input. The select (S0, S1, S2) inputs control the data path of the multiplexer/demultiplexer. When OE is low, the multiplexer/demultiplexer is enabled, and the A port is connected to the B port, allowing bidirectional data flow between ports. When OE is high, the multiplexer/demultiplexer is disabled, and a high-impedance state exists between the A and B ports.

This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry prevents damaging current backflow through the device when it is powered down. The device has isolation during power off.

To ensure the high-impedance state during power up or power down, OE must be tied to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
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Technical documentation

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Top documentation Type Title Format options Date
* Data sheet SN74CB3Q3251 1-of-8 FET Multiplexer/Demultiplexer 2.5V-3.3V Low-voltage High-bandwidth BUS Switch datasheet (Rev. B) PDF | HTML Aug 21, 2026
Application note Selecting the Correct Texas Instruments Signal Switch (Rev. E) PDF | HTML Jun 2, 2022
Application note Multiplexers and Signal Switches Glossary (Rev. B) PDF | HTML Dec 1, 2021
Application brief Eliminate Power Sequencing with Powered-off Protection Signal Switches (Rev. C) PDF | HTML Jan 6, 2021

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Simulation model

SN74CB3Q3251 IBIS Model

SCDM077.ZIP (42 KB) - IBIS model
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Package Pins CAD symbols, footprints & 3D models
TSSOP (PW) 16 Ultra Librarian
SSOP (DBQ) 16 Ultra Librarian
TVSOP (DGV) 16 Ultra Librarian
VQFN (RGY) 16 Ultra Librarian
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