Texas Instruments SN74CBT3253CDBQR

Overview

SN74CBT3253CDBQR from Texas Instruments is a dual 1-of-4 FET multiplexer/demultiplexer bus switch operating at 4 V–5.5 V, featuring 3 Ω typical ON-state resistance, –2 V undershoot protection on A/B ports, bidirectional signal flow, and 5.5 pF typical OFF-state I/O capacitance. It enables low-distortion USB interface and bus isolation in mixed-voltage digital systems.

For engineers reviewing the SN74CBT3253CDBQR datasheet, SN74CBT3253CDBQR pinout, SN74CBT3253CDBQR application, or SN74CBT3253CDBQR equivalent, this device serves as a high-speed, TTL-compatible analog/digital signal gate with Ioff partial-power-down support, 0–5 V signaling compatibility, and robust ESD/undershoot resilience for industrial and embedded data-path control.

Technical Context

The SN74CBT3253CDBQR integrates two independent 1-of-4 FET switches, each controlled by S0/S1 select lines and individual OE inputs (1OE, 2OE), enabling discrete path selection between four B-port terminals and one A-port terminal per channel. Its FET-based architecture delivers near-zero propagation delay (0.24 ns typical) and eliminates DC bias requirements.

Active undershoot-protection circuitry monitors A/B port voltages and forces switch disable when undershoot below –2 V occurs, maintaining off-isolation integrity. The device supports Ioff, ensuring no backflow current during partial power-down, and features clamp diodes on all control and I/O pins per JESD 22 standards.

Key Specifications

Pinout & Package

SN74CBT3253CDBQR uses a 16-pin SSOP (Shrink Small-Outline Package) with 0.65 mm pitch, 5.9 mm × 4.9 mm body size, and 1.75 mm max height per JEDEC MO-137 variation AB. Pin 1 is located at the top-left corner with index area marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3253CDBQR, SN74CBTD3384CDW offers greater bandwidth but sacrifices transient hardening, while PI3CH480QS provides more flexible routing at the cost of reduced undershoot tolerance and higher capacitive loading - making SN74CBT3253CDBQR optimal for compact, robust dual-path USB or industrial bus gating.

Availability

SN74CBT3253CDBQR is available at Aetrix Electronics and suitable for USB interface design, industrial bus isolation, low-distortion analog routing, and FPGA I/O expansion requiring stable component supply across production lifecycles.

Supply support for SN74CBT3253CDBQR 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 50 years of innovation in high-reliability signal-path components.

The SN74CBT3253CDBQR belongs to TI's CBT (Crosspoint Bus Transceiver) family, engineered specifically for low-latency, low-distortion digital and analog signal routing in mixed-voltage systems where timing integrity and transient resilience are critical.

FAQ

What is the maximum undershoot voltage the SN74CBT3253CDBQR can withstand without compromising off-isolation?

The SN74CBT3253CDBQR guarantees off-isolation integrity for undershoot events down to –2 V on A and B ports, enforced by internal active clamping circuitry that holds the FETs fully off during such transients. This specification is validated per the absolute maximum ratings table and confirmed in the Undershoot Characteristics section of the SCDS123B datasheet. Operation beyond –2 V risks unintended conduction or latch-up, so system-level transient suppression must be designed to stay within this limit for reliable SN74CBT3253CDBQR performance.

Does the SN74CBT3253CDBQR support 1.8-V logic inputs while operating at 5-V VCC?

Yes, the SN74CBT3253CDBQR supports 1.8-V logic-level control inputs (S0, S1, 1OE, 2OE) when VCC = 5 V, as confirmed by the recommended operating conditions: VIL ≤ 0.8 V and VIH ≥ 2 V ensure TTL and 3.3-V/5-V CMOS compatibility. Its input threshold is fixed relative to VCC, not rail-to-rail, so 1.8-V signals meet the VIH minimum and will reliably assert high logic states. This capability is explicitly cited in the FEATURES list under "Control Inputs Can Be Driven by TTL or 5-V/3.3-V CMOS Outputs" and applies directly to SN74CBT3253CDBQR.

Can the SN74CBT3253CDBQR be used to switch analog signals such as audio or sensor outputs?

Yes, the SN74CBT3253CDBQR is qualified for analog applications including audio routing and sensor signal multiplexing, as stated in the official description: "Supports Both Digital and Analog Applications". Its 3 Ω typical ron, 5.5 pF Cio(OFF), and flat frequency response (DC to >20 MHz) preserve signal fidelity without adding distortion or attenuation. The device exhibits no DC path or charge injection artifacts typical of CMOS analog switches, making it suitable for line-level audio, thermocouple, or bridge-sensor interfaces where SN74CBT3253CDBQR's bidirectional, rail-to-rail analog passband is leveraged.

What is the thermal resistance (θJA) of the SN74CBT3253CDBQR in its SSOP-DBQ package?

The SN74CBT3253CDBQR in the SSOP-DBQ package has a junction-to-ambient thermal resistance (θJA) of 90 °C/W, as specified in the Absolute Maximum Ratings table under "Package thermal impedance" for the DBQ package variant. This value is calculated per JESD 51-7 and assumes standard PCB layout with 1 in² copper pour. For continuous operation at full rated current, ambient temperature must remain below 75 °C to keep junction temperature within the 150 °C storage limit - a constraint verified in thermal simulations using TI's published θJA for SN74CBT3253CDBQR.

How does the Ioff feature of the SN74CBT3253CDBQR protect systems during partial power-down?

The Ioff feature of the SN74CBT3253CDBQR limits current to 10 µA maximum when VCC = 0 V and any I/O pin is biased between 0–5.5 V, preventing damaging backflow from powered domains into unpowered ones. This is achieved through internal transistor cutoff logic that disables all FET channels regardless of OE state. As documented in the datasheet's "Ioff Supports Partial-Power-Down Mode Operation" feature and Electrical Characteristics table, this behavior ensures safe hot-swap, modular power sequencing, and fault containment - a core reliability requirement explicitly guaranteed for SN74CBT3253CDBQR in systems with mixed power domains.