Texas Instruments CY74FCT2245CTQCT

Overview

CY74FCT2245CTQCT from Texas Instruments is an 8-bit noninverting bidirectional transceiver with 3-state outputs, designed for bus-oriented applications. It features 25-Ω output series resistors, I_off partial-power-down support, 12 mA sink / 15 mA source drive, and operates at 4.75–5.25 V over –40°C to 85°C. It replaces CY74FCT245T in existing designs where reduced transmission-line noise is critical.

For engineers reviewing the CY74FCT2245CTQCT datasheet, CY74FCT2245CTQCT pinout, CY74FCT2245CTQCT application, or CY74FCT2245CTQCT equivalent, key selection criteria include its 4.1 ns max propagation delay (t_PLH/t_PHL), 25-Ω integrated output termination, I_off protection during power-down, TTL-compatible logic levels, and SSOP-20 package compatibility with board-level noise mitigation requirements.

Technical Context

This device implements a dual-port bidirectional buffer architecture controlled by independent T/R (transmit/receive) and OE (output enable) inputs. The T/R signal determines data flow direction-high enables A→B, low enables B→A-while OE high forces both ports into high-impedance state. Its edge-rate control circuitry actively limits slew rate to suppress ringing and crosstalk on shared buses.

The integrated 25-Ω series output resistors are placed at each output terminal to match typical PCB trace impedance, reducing reflections without requiring external components. I_off functionality disables all outputs when V_CC = 0 V, preventing backflow current during partial system power-down-a requirement in hot-swap and modular subsystem designs.

Key Specifications

Pinout & Package

Package: SSOP-20 (DBQ), 7.4 mm × 5.3 mm body, 0.65 mm pitch, 1.2 mm max height, moisture sensitivity level 2 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bidirectional bus transceiver applications.

Compared with SN74FCT245ATPWR and 74LVC245APW, CY74FCT2245CTQCT uniquely delivers integrated 25-Ω termination + I_off + TTL compatibility in a single 5-V device - making it the optimal choice for retrofitting noise-sensitive legacy 5-V bus systems without redesigning termination networks.

Availability

CY74FCT2245CTQCT is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, legacy microcontroller bus expansion, and test equipment digital I/O subsystems requiring stable component supply and long-term lifecycle continuity.

Supply support for CY74FCT2245CTQCT 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 decades of experience in industrial, automotive, and communications IC design.

CY74FCT2245CTQCT belongs to TI's 74FCT logic family, engineered specifically for high-noise-immunity, 5-V bus interfacing in mission-critical industrial and automotive control systems where reliability and signal integrity are non-negotiable.

FAQ

What is the maximum operating frequency supported by CY74FCT2245CTQCT?

CY74FCT2245CTQCT does not specify a maximum clock frequency, but its 4.1 ns maximum propagation delay (t_PLH/t_PHL) supports reliable 8-bit parallel data transfer at effective bus rates up to approximately 240 MHz in ideal conditions. Real-world timing depends on load capacitance, trace length, and system-level setup/hold margins. For CY74FCT2245CTQCT, ensure total capacitive load stays ≤50 pF per pin to maintain datasheet performance.

Does CY74FCT2245CTQCT require external pull-up or pull-down resistors on control inputs?

No - CY74FCT2245CTQCT has no internal weak pull-ups or pull-downs on T/R or OE inputs. Per TI's recommended operating conditions, all unused inputs must be externally held at V_CC or GND to prevent floating states that cause increased ICC current and potential logic instability. For CY74FCT2245CTQCT, tie OE to GND via 10-kΩ resistor if permanently enabled, or to V_CC if permanently disabled.

Can CY74FCT2245CTQCT be used in place of CY74FCT245T without PCB changes?

Yes - CY74FCT2245CTQCT is functionally and pinout-compatible with CY74FCT245T in the same SSOP-20 package, and TI explicitly states it can replace CY74FCT245T in existing designs. Both share identical pin mapping, electrical specs, and timing. The key advantage of CY74FCT2245CTQCT is its integrated 25-Ω output resistors, which reduce external component count without altering footprint or routing for CY74FCT2245CTQCT.

What is the purpose of the 25-Ω output series resistors in CY74FCT2245CTQCT?

The 25-Ω output series resistors in CY74FCT2245CTQCT are integrated to dampen transmission-line reflections on PCB traces, particularly in unterminated or lightly loaded bus configurations. They match typical FR-4 microstrip impedance (≈50 Ω) when paired with complementary trace geometry, reducing overshoot, undershoot, and ringing. This eliminates the need for eight discrete resistors per port - a direct design simplification confirmed in the CY74FCT2245CTQCT datasheet.

How does I_off protection work in CY74FCT2245CTQCT during partial power-down?

In CY74FCT2245CTQCT, the I_off circuitry actively disables all output drivers when V_CC = 0 V, limiting leakage current to ±1 µA even if A or B port signals remain at 4.5 V. This prevents damaging reverse current flow from live buses into the unpowered IC, a critical feature for hot-swap capable systems. The I_off behavior is verified across temperature and voltage extremes in the CY74FCT2245CTQCT datasheet's electrical characteristics table.