Texas Instruments CY74FCT2257ATQCT

Overview

CY74FCT2257ATQCT from Texas Instruments is a quad 2-input multiplexer with 3-state outputs in a 16-pin SSOP package, operating at 4.75–5.25 V, delivering 12 mA sink / 15 mA source drive, 25-Ω integrated output series resistance, and propagation delays as low as 1.5 ns. It serves as a logic-controlled 4-pole, 2-position switch in bus-multiplexed digital systems requiring noise-suppressed signal routing.

For engineers reviewing the CY74FCT2257ATQCT datasheet, CY74FCT2257ATQCT pinout, CY74FCT2257ATQCT application, or CY74FCT2257ATQCT equivalent, this device is selected for high-speed TTL-compatible data selection with Ioff-enabled partial-power-down support, edge-rate control, and on-die termination - critical for stable operation in dense PCB layouts with shared buses.

Technical Context

The CY74FCT2257ATQCT implements four independent 2:1 multiplexers sharing one common select (S) and one active-low output-enable (OE) input. Each channel routes either I0x or I1x to Yx based on S logic level, with noninverted output polarity and simultaneous 3-state control via OE.

Its FCT-family architecture integrates 25-Ω series output resistors to damp transmission-line reflections, employs edge-rate control circuitry to reduce switching noise, and features Ioff protection enabling safe operation during partial power-down when VCC = 0 V and I/O pins are biased up to 4.5 V.

Key Specifications

Pinout & Package

Package: 16-pin Shrink Small-Outline Package (SSOP), DBQ variant, 3.9 mm × 4.9 mm body, 1.75 mm max height, 0.635 mm pitch, RoHS-compliant NIPDAU finish, MSL Level-2-260°C-1 year.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2-input multiplexer applications.

Compared with CY74FCT2257CTQCT, the CY74FCT2257ATQCT trades 0.7 ns of speed margin for enhanced noise immunity via optimized edge-rate control; versus SN74F257N, it provides modern SMT packaging, Ioff safety, and 40% lower propagation delay - making CY74FCT2257ATQCT the preferred choice for industrial and embedded applications requiring reliability and density.

Availability

CY74FCT2257ATQCT is available at Aetrix Electronics and suitable for industrial control systems, automated test equipment, and digital logic prototyping requiring stable component supply, long-term lifecycle support, and RoHS-compliant SSOP packaging.

Supply support for CY74FCT2257ATQCT 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 logic solutions, with over 50 years of innovation in high-reliability digital interface components.

The CY74FCT2257ATQCT belongs to TI's FCT logic family, engineered for noise-immune, high-speed 5-V digital signal routing in industrial, telecom, and computing infrastructure where signal integrity and power-down safety are critical.

FAQ

What is the maximum operating frequency supported by CY74FCT2257ATQCT?

The CY74FCT2257ATQCT has a maximum propagation delay of 5 ns (tPHL/tPLH), supporting reliable operation in systems with clock periods ≥10 ns - corresponding to a practical upper limit of ~100 MHz for synchronous data selection. Actual usable frequency depends on board layout, load capacitance, and setup/hold timing margins of connected devices; the CY74FCT2257ATQCT itself does not include internal clocking or frequency-limiting circuitry.

Does CY74FCT2257ATQCT support partial power-down mode?

Yes, CY74FCT2257ATQCT supports partial power-down mode via its Ioff feature. When VCC = 0 V, the device disables all outputs and limits Ioff current to ±1 µA even if I/O pins are biased up to 4.5 V - preventing damaging back-current flow in mixed-power-rail systems. This capability is explicitly verified in the datasheet's absolute maximum and electrical characteristics tables.

Is CY74FCT2257ATQCT pin-compatible with older 74-series multiplexers?

CY74FCT2257ATQCT is functionally and pin-compatible with the industry-standard 74F257 and 74LS257 in the 16-pin SSOP (DBQ) package, sharing identical pin assignments for I0/I1 inputs, S, OE, Y outputs, VCC, and GND. However, it is not pin-compatible with DIP-packaged variants due to differing physical footprints - the CY74FCT2257ATQCT requires an SSOP-16 land pattern.

What is the purpose of the 25-Ω output series resistance in CY74FCT2257ATQCT?

The 25-Ω output series resistance in CY74FCT2257ATQCT is integrated to match typical PCB trace impedance (≈50 Ω single-ended), thereby reducing signal reflections, overshoot, and ringing on unterminated lines up to ~10 cm in length. This eliminates the need for external series termination resistors, simplifying layout and improving signal integrity in high-speed digital interconnects without degrading propagation delay.

Can CY74FCT2257ATQCT interface directly with 3.3-V logic devices?

CY74FCT2257ATQCT accepts 3.3-V logic inputs safely - its VIH threshold is 2.0 V min and VIL is 0.8 V max, well within 3.3-V CMOS logic swing. However, its outputs swing to 5-V levels (VOH ≥2.4 V), so direct connection to 3.3-V-only inputs requires level translation or clamping to avoid overvoltage damage; the CY74FCT2257ATQCT itself does not provide bidirectional voltage translation.