NXP Semiconductors CBTS3257D,112

Overview

CBTS3257D,112 from NXP Semiconductors (formerly Philips) is a quad 1-of-2 TTL-compatible analog multiplexer/demultiplexer with Schottky diode I/O clamping. It features 5 Ω on-resistance, <0.25 ns propagation delay through the switch path, and operates from –40 °C to +85 °C at 4.5–5.5 V supply. It enables bidirectional signal routing in high-speed digital logic interfaces.

For engineers reviewing the CBTS3257D,112 datasheet, CBTS3257D,112 pinout, CBTS3257D,112 application, or CBTS3257D,112 equivalent, key selection criteria include on-resistance matching across channels, undershoot protection via integrated Schottky diodes, 3-state output control timing, and SO16 package compatibility with legacy 5 V TTL systems.

Technical Context

The CBTS3257D,112 implements four independent 1-of-2 bidirectional analog switches controlled by shared select (S) and output enable (OE) inputs. Each channel connects one A input to either B1 or B2 output based on S logic level when OE is low.

Its internal Schottky diodes clamp I/O undershoot to –0.8 V (A/B) and –1.2 V (control pins), satisfying JESD22-A114 (2000 V HBM) ESD robustness. The device uses standard TTL-compatible voltage thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) and exhibits latch-up immunity >500 mA per JESD78.

Key Specifications

Pinout & Package

CBTS3257D,112 is supplied in a 16-pin plastic SO package (SOT109-1), 3.9 mm body width, with standard 1.27 mm lead pitch and gull-wing leads for surface-mount assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3257DR and 74LVC1G3157GW, the CBTS3257D,112 uniquely combines quad-channel integration, sub-ns switching, and factory-integrated Schottky undershoot protection in a legacy 5 V SO16 footprint-making it irreplaceable in retrofitting and industrial maintenance of 5 V TTL-based systems.

Availability

CBTS3257D,112 is available at Aetrix Electronics and suitable for PCI bus signal routing, ISA expansion interface sharing, JTAG test access multiplexing, and embedded debug port switching requiring stable component supply and long-term industrial availability.

Supply support for CBTS3257D,112 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

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with roots in Philips' pioneering logic IC development.

The CBTS3257D,112 belongs to NXP's legacy high-speed TTL-compatible analog switch family, designed specifically for robust signal routing in 5 V industrial control backplanes, test equipment, and retrofitted computing infrastructure.

FAQ

What is the maximum continuous current rating per channel for CBTS3257D,112?

The CBTS3257D,112 supports a maximum continuous channel current of 128 mA, as specified in its Absolute Maximum Ratings table. This rating applies under recommended operating conditions (V_CC = 4.5–5.5 V, T_amb = –40 to +85 °C) and ensures safe conduction without thermal runaway or contact degradation. Exceeding this value risks permanent damage to the internal switch elements. Always verify actual load current in your design against this limit when using CBTS3257D,112 in signal routing or power-switching roles.

Does CBTS3257D,112 support bidirectional signal flow between A and B ports?

Yes, CBTS3257D,112 supports fully bidirectional analog signal flow between each A input and its corresponding B1/B2 outputs. Its MOSFET-based switch architecture has no intrinsic directionality - signals pass equally well from A to B or B to A, provided the voltage difference remains within the device's absolute maximum ratings (–0.5 V to V_CC + 0.5 V). This makes CBTS3257D,112 suitable for both multiplexing (A→B) and demultiplexing (B→A) in the same circuit configuration.

What is the purpose of the Schottky diodes in CBTS3257D,112?

The Schottky diodes in CBTS3257D,112 provide integrated I/O undershoot protection, clamping negative transients on A, B1, and B2 pins to –0.8 V (and control pins to –1.2 V) during fast edge transitions or ESD events. This prevents gate oxide stress in downstream CMOS devices and eliminates the need for discrete external clamping diodes in many 5 V TTL systems. The diodes are intrinsic to the CBTS3257D,112 silicon design and require no external components to function - a key differentiator from alternatives like the SN74CBT3257DR.

Can CBTS3257D,112 operate reliably at 3.3 V supply voltage?

No, CBTS3257D,112 is not characterized or guaranteed for operation at 3.3 V. Its Recommended Operating Conditions specify a minimum V_CC of 4.5 V and maximum of 5.5 V. At 3.3 V, the internal switch may not fully turn on, resulting in elevated on-resistance (>15 Ω), increased propagation delay, and potential logic threshold violations. For 3.3 V systems, consider modern alternatives such as the 74LVC1G3157, but note that CBTS3257D,112 itself must be used strictly within its 4.5–5.5 V range to meet datasheet performance.

Is CBTS3257D,112 pin-compatible with other members of the CBTS3257 family?

Yes, CBTS3257D,112 shares identical pinout and function with CBTS3257DB, CBTS3257DS, and CBTS3257PW - all are quad 1-of-2 mux/demux variants differing only in package (SO, SSOP, QSOP, TSSOP) and topside marking. The CBTS3257D,112 (SO16/SOT109-1) can be substituted for any of these in socketed or rework scenarios where mechanical fit allows, provided thermal and layout constraints (e.g., trace inductance, decoupling) are validated for the new package. Electrical behavior remains identical across the family.