Texas Instruments SN74CBTLV3257PW

Overview

SN74CBTLV3257 from Texas Instruments is a low-voltage 4-bit 1-of-2 FET multiplexer/demultiplexer with 5 Ω on-state resistance, rail-to-rail switching capability, and I_off partial-power-down support. It routes bidirectional data between four A-side ports (1A–4A) and eight B-side ports (1B1/1B2 through 4B1/4B2) under control of S and active-low OE, enabling dynamic bus sharing in high-speed digital systems.

For engineers reviewing the SN74CBTLV3257 datasheet, SN74CBTLV3257 pinout, SN74CBTLV3257 application, or SN74CBTLV3257 equivalent, key selection considerations include its 5 Ω switch R_on, 0.25 ns typical propagation delay at 2.5 V, ±128 mA channel current rating, −40 °C to 85 °C operating range (PW package), and TSSOP-16 footprint compatibility with layout-sensitive high-frequency signal paths.

Technical Context

The SN74CBTLV3257 implements four independent bidirectional analog/digital switches, each selectable between two B-side terminals (B1/B2) via a single S input. Its FET-based architecture enables rail-to-rail voltage transfer without level-shifting, supporting logic families from 2.3 V to 3.6 V V_CC.

Functional operation is governed by a two-level enable hierarchy: OE must be low for any switching, and S selects which B port connects to each A port. When OE is high, all switches enter high-impedance isolation - reinforced by I_off leakage <15 µA at V_CC = 0 V - ensuring safe back-drive protection during power sequencing.

Key Specifications

Pinout & Package

Packaged in a 16-pin TSSOP (PW) measuring 5.00 mm × 4.40 mm, the SN74CBTLV3257 features gull-wing leads optimized for automated assembly and thermal performance (R_θJA = 129.1 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTLV3257, SN74CBT3257PW trades I_off safety and 2.5 V compatibility for 5 V operation, while TS3A227EYZTR offers superior R_on and ESD in a smaller 2-channel format - neither replicates the exact 4-bit, I_off-enabled, TSSOP-16 feature set of the SN74CBTLV3257.

Availability

SN74CBTLV3257 is available at Aetrix Electronics and suitable for datacenter bus arbitration, industrial motor drive interface, and wired networking PHY switching requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant TSSOP packaging.

Supply support for SN74CBTLV3257 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 and embedded processing technologies, with over 90 years of innovation in precision analog, high-speed logic, and power management ICs.

The SN74CBTLV3257 belongs to TI's CBTLV (low-voltage BiCMOS logic) family, engineered for high-speed, low-power signal routing in enterprise infrastructure, communications, and industrial control systems where signal integrity and power sequencing safety are critical.

FAQ

What is the maximum operating frequency supported by the SN74CBTLV3257?

The SN74CBTLV3257 is characterized for operation up to 200 MHz, based on its 0.25 ns maximum propagation delay at 2.5 V and low 5 Ω on-state resistance. Real-world frequency capability depends on PCB layout, load capacitance, and signal edge rates - TI recommends keeping trace lengths short and using controlled-impedance routing to maintain signal integrity above 100 MHz. The SN74CBTLV3257 datasheet confirms this limit in Section 8.2.1.

Does the SN74CBTLV3257 support level shifting between different logic voltages?

No, the SN74CBTLV3257 does not perform active level shifting. It provides rail-to-rail bidirectional switching, meaning it passes signals from 0 V to V_CC without clamping, but both sides of each switch must operate within the same V_CC domain (2.3–3.6 V). For true level translation between disparate voltage rails (e.g., 1.8 V ↔ 3.3 V), a dedicated level shifter such as the TXS0108E is required. The SN74CBTLV3257 preserves logic levels only within its configured supply range.

How should the OE pin be connected to ensure proper power-up behavior of the SN74CBTLV3257?

To guarantee high-impedance state during power-up and power-down, the OE pin of the SN74CBTLV3257 must be tied to V_CC through an external pullup resistor. TI specifies that the minimum resistor value depends on the current-sinking capability of the driving source - typically 10 kΩ suffices for most microcontroller GPIOs. Leaving OE floating or unconnected risks undefined switching states and potential bus contention. This requirement is explicitly stated in Section 7.1 of the SN74CBTLV3257 datasheet.

Can the SN74CBTLV3257 handle analog signals such as audio or sensor outputs?

Yes, the SN74CBTLV3257 can route analog signals within its voltage and bandwidth limits: DC to ~200 MHz, 0 V to V_CC, and ≤±128 mA per channel. Its 5 Ω R_on and low off-capacitance (5.5 pF) minimize distortion and loading, making it suitable for low-frequency analog paths like thermistor bridges or digital audio I²S clock lines. However, it is not specified for high-fidelity audio due to lack of THD or SNR characterization - for such use cases, TI's TS5A series analog switches are preferred. The SN74CBTLV3257 datasheet confirms analog usability in Section 7.3.

What is the thermal performance of the SN74CBTLV3257 in the PW (TSSOP-16) package?

In the PW package, the SN74CBTLV3257 has a junction-to-ambient thermal resistance (R_θJA) of 129.1 °C/W under standard JEDEC test conditions. With a maximum junction temperature of 150 °C and ambient of 85 °C, this allows up to ~500 mW total power dissipation before thermal derating. Layout practices - including copper pour under the exposed pad (if present) and thermal vias - significantly improve real-world performance. These values are documented in Table 5.3 of the SN74CBTLV3257 datasheet.