Texas Instruments SN74CB3Q16244DGGR

Overview

SN74CB3Q16244 from Texas Instruments is a 16-bit FET bus switch with four independent 4-bit channels, 5-V tolerant I/Os, 5 Ω typical ON-state resistance (ron), rail-to-rail 0–5 V switching at 3.3 V VCC, and 20 MHz maximum OE switching frequency. It enables bidirectional signal routing in high-speed data paths of optical networking and wireless infrastructure equipment.

For engineers reviewing the SN74CB3Q16244 datasheet, SN74CB3Q16244 pinout, SN74CB3Q16244 application, or SN74CB3Q16244 equivalent, key selection criteria include its 4 pF typical OFF-state I/O capacitance, partial-power-down support via Ioff, flat ron over voltage/temperature, 500 MHz bandwidth capability, and TSSOP-48 package compatibility with dense PCB layouts.

Technical Context

The SN74CB3Q16244 implements a charge-pump–enhanced FET architecture to elevate gate voltage and maintain low, flat ron across 2.3–3.6 V VCC and full 0–5 V I/O swing. Each of its four OE inputs controls a dedicated 4-bit bidirectional channel with near-zero propagation delay (0.18 ns typical) and no direction pin required.

It supports true 5-V tolerance on all A/B I/Os regardless of VCC state (powered up or down), includes undershoot clamp diodes on control and data pins, and features Ioff circuitry that blocks backflow current during partial power-down-enabling hot-swap and system-level power sequencing.

Key Specifications

Pinout & Package

TSSOP-48 (DGG) package: 12.50 mm × 6.10 mm body, 0.5 mm pitch, surface-mount, lead-free (NiPdAu), moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CB3Q16244, SN74CBT16244DGGR offers lower cost but sacrifices 2.5/3.3-V operation and 5-V tolerance, while SN74LVC16244ADGGR provides deterministic drive strength but lacks true bidirectional switching, Ioff, and rail-to-rail capability - making SN74CB3Q16244 uniquely suited for mixed-signal, hot-swap, and high-bandwidth interconnect roles.

Availability

SN74CB3Q16244 is available at Aetrix Electronics and suitable for optical networking, wireless infrastructure, and telecom equipment requiring stable component supply, long-lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for SN74CB3Q16244 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, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The CB3Q family-including SN74CB3Q16244-is engineered for high-bandwidth, low-distortion signal routing in broadband communications systems where rail-to-rail switching, 5-V tolerance, and partial-power-down resilience are mandatory.

FAQ

What is the maximum signal frequency supported by the SN74CB3Q16244?

The SN74CB3Q16244 supports a high-bandwidth data path up to 500 MHz, verified by TI's characterization under typical operating conditions. This performance relies on its 5 Ω typical ON-state resistance and 4 pF OFF-state I/O capacitance, which jointly minimize RC time constants and preserve signal edge rates. Actual usable bandwidth in a given design depends on PCB layout, termination, and load capacitance - but the device itself is rated for 500 MHz small-signal operation per the official datasheet (SCDS168A).

Can the SN74CB3Q16244 safely interface 5-V signals while powered from a 2.5-V supply?

Yes, the SN74CB3Q16244 supports 0–5-V switching with 2.5-V VCC, as explicitly specified in the datasheet. Its charge-pump circuit elevates the gate voltage to ensure full enhancement of the pass FETs, enabling rail-to-rail conduction without degradation in ron or timing. All A/B I/Os remain 5-V tolerant whether VCC is 2.5 V, 3.3 V, or even 0 V - a key differentiator from standard CMOS switches.

How does the Ioff feature of the SN74CB3Q16244 protect the system during partial power-down?

The Ioff circuitry in the SN74CB3Q16244 actively disables current flow between A and B ports when VCC = 0 V, limiting leakage to ≤1 µA. This prevents back-driving of powered-down sections by live upstream or downstream circuits - a critical safeguard in modular systems like pluggable optical modules or hot-swappable line cards. Unlike passive high-Z states, Ioff provides active isolation compliant with JESD78 Class II latch-up immunity.

What is the recommended bypass capacitor configuration for the SN74CB3Q16244?

TI specifies one 0.022 µF ceramic capacitor per VCC pin (pins 7, 18, 31, 42), placed as close as possible to each pin with minimal trace length. This configuration targets high-frequency noise suppression specific to the device's fast switching behavior. Bulk capacitance (e.g., 0.1 µF or 1 µF) may be added elsewhere on the rail, but the 0.022 µF local caps are mandatory per the datasheet's Power Supply Recommendations section to prevent VCC droop during 20 MHz OE transitions.

Does the SN74CB3Q16244 require external pull-up resistors on its OE pins?

Yes - to ensure a defined high state during power-up or power-down, each OE pin (1OE, 2OE, 3OE, 4OE) must be tied to VCC via an external pull-up resistor. The minimum value depends on the driving source's sink capability, but 10 kΩ is commonly used. Without this, OE could float, causing unintended channel activation or contention. The datasheet explicitly states: "OE should be tied to VCC through a pullup resistor" to guarantee high-impedance state at power transition boundaries.