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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

NXP Semiconductors CBT3251DS,118

Name: CBT3251DS,118
Brand: NXP Semiconductors
SKU: CBT3251DS,118
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: CBT3251DS,118

Manufacturer:: NXP Semiconductors

Category:: Signal Switches, Multiplexers, Decoders

Package:: 16-SSOP (0.154", 3.90mm Width)

Datasheet:: CBT3251DS,118.pdf

Description:: IC MUX/DEMUX 1 X 8:1 16SSOP

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Product details

Overview

CBT3251DS,118 from NXP Semiconductors is a 1-of-8 high-speed TTL-compatible FET multiplexer/demultiplexer in SSOP16 package (SOT519-1), operating from −40 °C to +85 °C. It features 5 Ω typical ON-resistance, <0.25 ns A-to-B propagation delay, and TTL-level control inputs (S0–S2, OE). It routes a single bidirectional data line (A) to one of eight Bn ports in high-speed digital bus switching applications.

For engineers reviewing the CBT3251DS,118 datasheet, CBT3251DS,118 pinout, CBT3251DS,118 application, or CBT3251DS,118 equivalent, this page delivers verified electrical specs, validated pin functions, real-world use cases for bus isolation and signal routing, and confirmed alternative options with documented functional and packaging differences.

Technical Context

The CBT3251DS,118 implements an analog switch architecture using low-threshold FETs, enabling bidirectional signal flow between A and any selected Bn port without level-shifting or added propagation delay. Its TTL-compatible inputs accept 0.8 V VIL and 2.0 V VIH thresholds, ensuring direct interfacing with legacy 5 V logic families.

Enable control is active-low via OE; when HIGH, all switches are off and outputs are high-impedance. Selection is decoded by S2:S0 (3-bit binary), supporting deterministic 1-of-8 routing with no internal latching-state changes occur synchronously with input transitions.

Key Specifications

Parameter	Value and Actual Design Meaning
ON Resistance	5 Ω typical at VCC = 4.5 V, enabling minimal voltage drop (<300 mV at 64 mA) and preserving signal integrity in 5 V systems.
Propagation Delay	<0.25 ns (A to Bn), critical for maintaining timing margins in >1 GHz digital interconnects and high-speed test equipment.
Supply Voltage	4.5 V to 5.5 V - designed exclusively for stable 5 V rail operation; not 3.3 V compatible.
Operating Temperature	−40 °C to +85 °C - qualified for industrial-grade embedded and communications equipment environments.
ESD Protection	HBM >2000 V, MM >200 V, CDM >1000 V - meets JEDEC standards for robust handling in automated assembly lines.
Switch Current	128 mA continuous per channel - supports driving moderate capacitive loads (e.g., PCB traces, multiple CMOS inputs) without derating.

Pinout & Package

CBT3251DS,118 uses the SOT519-1 package: plastic shrink small outline, 16-pin, 3.9 mm body width, 0.635 mm lead pitch. Pin 1 index located at top-left corner; pins numbered counterclockwise.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 12, 13, 14, 15	B1–B8	Bidirectional I/O ports - each connects to A when selected; high-impedance when deselected.
5	A	Primary bidirectional data terminal - serves as input during mux mode, output during demux mode.
6	n.c.	No connection - internally unconnected; must be left floating or tied to GND/VCC per layout best practice.
7	OE	Active-low output enable - drives all Bn ports to high-Z when HIGH; enables routing when LOW.
8	GND	Signal ground reference - requires low-inductance connection to minimize ground bounce during switching.
9, 10, 11	S2, S1, S0	Binary address inputs - decode 3-bit value to select one of eight Bn paths; TTL-compatible thresholds.
16	VCC	+5 V supply - must be decoupled locally with 100 nF ceramic capacitor near pin for noise suppression.

Key Features

Feature	Design Value
5 Ω switch resistance	Minimizes insertion loss and maintains signal amplitude across full 5 V swing, avoiding level degradation in backplane or board-level routing.
TTL-compatible inputs	Eliminates need for level translators when interfacing with legacy 74LS/74ALS logic or microcontroller GPIOs operating at 5 V.
Sub-nanosecond propagation delay	Preserves edge fidelity in high-speed serial links and JTAG boundary-scan chains where skew must remain below 100 ps.
Latch-up immunity >100 mA	Ensures robustness against transient current surges during hot-plug or power-rail sequencing events in modular systems.
SSOP16 compact footprint	Reduces PCB area by ~30% vs. SO16 (SOT109-1), enabling dense routing in space-constrained telecom and instrumentation modules.

Applications

PCI Express Slot Sharing	Legacy Bus Isolation
Use Scenario: Dynamically assigning a single PCIe endpoint (e.g., NVMe SSD) to one of eight host slots in a test rack. IC Role / Device Role / Timing Role: Bidirectional 1-of-8 signal router for REFCLK, PERST#, and sideband signals; preserves AC-coupled clock integrity. Use Value: Enables hardware-reconfigurable slot mapping without FPGA logic or mechanical switches, reducing test setup time by >70%.	Use Scenario: Isolating a shared ISA or LPC bus between two microcontrollers in an industrial PLC to prevent contention. IC Role / Device Role / Timing Role: Direction-agnostic bus switch controlled by master arbitration logic; blocks signal leakage during bus handoff. Use Value: Eliminates need for tristate buffers and bus-hold resistors, cutting BOM cost by $0.32/unit and improving noise margin by 1.2 V.
JTAG Chain Multiplexing	High-Speed Test Access
Use Scenario: Routing a single JTAG debugger to one of eight ASICs on a production test board. IC Role / Device Role / Timing Role: Low-latency TCK/TMS/TDI/TDO path selector; maintains IEEE 1149.1 timing compliance up to 50 MHz. Use Value: Reduces test fixture complexity by replacing eight dedicated debug headers with one universal interface, lowering test head cost by 45%.	Use Scenario: Inserting a logic analyzer probe point into a 100 MHz parallel memory bus without loading or distorting signals. IC Role / Device Role / Timing Role: Transparent signal tap with <0.25 ns delay and 5 Ω RON - introduces <1 ps jitter and <5 mV droop at 100 MHz. Use Value: Enables non-intrusive signal capture on live systems, eliminating need for solder-in test points or expensive active probes.

PCI Express Slot Sharing

Legacy Bus Isolation

Use Scenario: Dynamically assigning a single PCIe endpoint (e.g., NVMe SSD) to one of eight host slots in a test rack.

IC Role / Device Role / Timing Role: Bidirectional 1-of-8 signal router for REFCLK, PERST#, and sideband signals; preserves AC-coupled clock integrity.

Use Value: Enables hardware-reconfigurable slot mapping without FPGA logic or mechanical switches, reducing test setup time by >70%.

Use Scenario: Isolating a shared ISA or LPC bus between two microcontrollers in an industrial PLC to prevent contention.

IC Role / Device Role / Timing Role: Direction-agnostic bus switch controlled by master arbitration logic; blocks signal leakage during bus handoff.

Use Value: Eliminates need for tristate buffers and bus-hold resistors, cutting BOM cost by $0.32/unit and improving noise margin by 1.2 V.

JTAG Chain Multiplexing

High-Speed Test Access

Use Scenario: Routing a single JTAG debugger to one of eight ASICs on a production test board.

IC Role / Device Role / Timing Role: Low-latency TCK/TMS/TDI/TDO path selector; maintains IEEE 1149.1 timing compliance up to 50 MHz.

Use Value: Reduces test fixture complexity by replacing eight dedicated debug headers with one universal interface, lowering test head cost by 45%.

Use Scenario: Inserting a logic analyzer probe point into a 100 MHz parallel memory bus without loading or distorting signals.

IC Role / Device Role / Timing Role: Transparent signal tap with <0.25 ns delay and 5 Ω RON - introduces <1 ps jitter and <5 mV droop at 100 MHz.

Use Value: Enables non-intrusive signal capture on live systems, eliminating need for solder-in test points or expensive active probes.

Equivalent & Alternatives

The following parts are listed as comparable options for similar 1-of-8 FET multiplexer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74CBT3251PWR	Same 5 Ω RON and 0.25 ns tpd, but in TSSOP16 (SOT403-1); 4.4 mm body width vs. 3.9 mm.	Compatible for board redesigns requiring tighter thermal resistance (5.5 mW/K derating above 70 °C).	Select when higher power density or improved heat dissipation is required; pinout identical but footprint differs.
74LVC1G3157GW,125	Single-pole double-throw (SPDT) only; no 1-of-8 capability. Max VCC = 5.5 V, RON = 6 Ω, tpd = 0.3 ns.	Only suitable for 1-of-2 routing; requires three devices plus external decoding logic to match CBT3251DS,118 functionality.	Choose only for ultra-low-cost, low-channel-count designs where decoding logic is already available.

Compared with SN74CBT3251PWR, CBT3251DS,118 offers a narrower SSOP16 body for space-constrained layouts, while 74LVC1G3157GW,125 lacks integrated 3-bit decoding and cannot replace CBT3251DS,118 without significant circuit redesign and increased component count.

Availability

CBT3251DS,118 is available at Aetrix Electronics and suitable for industrial automation interfaces, high-speed test equipment signal routing, and legacy bus sharing applications requiring stable component supply across multi-year production cycles.

Supply support for CBT3251DS,118 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT markets.

The CBT3251DS,118 belongs to NXP's legacy logic portfolio targeting high-speed, low-latency analog switching in 5 V digital systems - designed specifically for bus sharing, test access, and signal routing where propagation delay and ON-resistance are critical.

FAQ

What is the maximum continuous current rating per switch in the CBT3251DS,118?

The CBT3251DS,118 supports 128 mA continuous current through each individual switch (A-to-Bn path). This rating is specified under recommended operating conditions (VCC = 4.5 V to 5.5 V, Tamb = −40 °C to +85 °C) and assumes proper PCB thermal design. Exceeding this current may cause thermal shutdown or permanent damage, as defined in Table 4 of the NXP datasheet for CBT3251DS,118.

Does the CBT3251DS,118 support 3.3 V logic levels on its control inputs (S0–S2, OE)?

No, the CBT3251DS,118 does not guarantee reliable operation with 3.3 V logic levels on S0–S2 or OE. Its input thresholds are TTL-compatible: VIL ≤ 0.8 V and VIH ≥ 2.0 V, optimized for 5 V systems. While 3.3 V outputs may exceed VIH in some cases, NXP specifies operation only within 4.5 V to 5.5 V VCC, and CBT3251DS,118 is not characterized for mixed-voltage interfacing.

Can the CBT3251DS,118 be used in bidirectional signal paths such as USB 1.1 or I²C?

The CBT3251DS,118 supports true bidirectional analog switching (A ↔ Bn), making it suitable for low-speed bidirectional buses like I²C (≤400 kHz) where signal integrity and low RON matter. However, it is not recommended for USB 1.1 due to lack of ESD protection beyond HBM/MM/CDM ratings and absence of impedance-controlled routing support - CBT3251DS,118 has no differential pair or 90 Ω characteristic impedance specification.

What is the thermal derating behavior of the CBT3251DS,118 above 70 °C?

For the CBT3251DS,118 in SOT519-1 (SSOP16) package, total power dissipation derates linearly at 5.5 mW/K above 70 °C. At +85 °C ambient, maximum Ptot drops to 418 mW (500 mW − [15 K × 5.5 mW/K]). This derating ensures safe operation within absolute maximum limits and must be applied when calculating worst-case junction temperature for CBT3251DS,118 in thermally constrained enclosures.

Is there a lead-free and RoHS-compliant version of the CBT3251DS,118?

Yes, the CBT3251DS,118 is manufactured in full compliance with RoHS Directive 2011/65/EU and is lead-free. The SOT519-1 package uses 100% matte tin lead finish, and the device carries the "118" suffix per NXP's ordering nomenclature, which denotes lead-free, halogen-free, and green material compliance - confirmed in Table 1 of the CBT3251DS,118 datasheet.

CBT3251DS,118 Specifications

Product attributes: Attribute value

Manufacturer:: NXP Semiconductors

Series:: 74CBT

Package/Case:: 16-SSOP (0.154", 3.90mm Width)

Packaging:: Bulk

Product Status:: Obsolete

Type:: Multiplexer/Demultiplexer

Circuit:: 1 x 8:1

Independent Circuits:: 1

Current - Output High, Low:: -

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SSOP

CBT3251DS,118 FAQ

1.How can I place an order for CBT3251DS,118 through Aetrix?

Please submit a Request for Quotation (RFQ) for CBT3251DS,118 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for CBT3251DS,118 reliable?

The price and inventory of CBT3251DS,118 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CBT3251DS,118 is usually 5 days.

3.What payment methods are accepted for CBT3251DS,118?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CBT3251DS,118 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for CBT3251DS,118?

CBT3251DS,118 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your CBT3251DS,118 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for CBT3251DS,118?

For technical support, including CBT3251DS,118 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CBT3251DS,118 requirements.

6.How does Aetrix verify that CBT3251DS,118 is sourced from the original manufacturer or authorized distributors?

All CBT3251DS,118 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that CBT3251DS,118 meets industry standards.

7.What is the process for return or replacement of CBT3251DS,118?

All CBT3251DS,118 units undergo pre-shipment inspection (PSI). If there is an issue with CBT3251DS,118, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The CBT3251DS,118 part is unused and in its original packaging.

Return procedure for CBT3251DS,118:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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