onsemi 74LVT2245MTCX

Overview

74LVT2245MTCX from Fairchild Semiconductor is a low-voltage octal bidirectional transceiver with 3-STATE inputs/outputs, integrated 25Ω series resistors on B-port outputs, and 3.3V supply operation compatible with 5V TTL interfaces. It supports bus-oriented data transfer between A and B ports under T/R control, features ±12mA/±64mA drive capability per port, and operates across –40°C to +85°C.

For engineers reviewing the 74LVT2245MTCX datasheet, pinout, applications, or equivalent options, key selection considerations include direction control logic (T/R), output enable timing (tPZH/tPHZ), B-port overshoot suppression via internal 25Ω resistors, and compatibility with mixed-voltage 3.3V/5V system interconnects.

Technical Context

The 74LVT2245MTCX implements non-inverting bidirectional buffering using advanced BiCMOS technology, enabling high-speed operation comparable to 5V ABT logic while maintaining low power dissipation. Its dual-port architecture uses a single Transmit/Receive (T/R) input to control data flow direction: active-HIGH enables A→B transfer; active-LOW enables B→A transfer.

Output Enable (OE) asserts high-impedance on both A and B ports simultaneously. The B-port outputs integrate 25Ω series resistors to reduce signal overshoot/undershoot in transmission-line environments, while A-port outputs deliver higher drive strength (–32mA/+64mA) for demanding bus loading. Power-up/down high-impedance behavior ensures glitch-free bus insertion.

Key Specifications

Pinout & Package

74LVT2245MTCX is housed in a 20-lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153 compliant, 4.4mm wide, with 0.65mm lead pitch and exposed pad not present. Pin 1 marked by notch or dot; pins numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC2245APW and 74LVX2245MTCX, the 74LVT2245MTCX uniquely delivers factory-integrated 25Ω B-port termination, 5V-tolerant inputs, and asymmetric high-drive A-port capability-making it optimal for industrial backplanes and mixed-voltage PCI extensions where signal integrity and interoperability are critical.

Availability

74LVT2245MTCX is available at Aetrix Electronics and suitable for PCI bus interface, memory expansion module, and industrial backplane interconnect applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for 74LVT2245MTCX 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in analog and mixed-signal ICs, power management, and interface solutions before its acquisition by ON Semiconductor in 2016.

The 74LVT2245MTCX belongs to Fairchild's LVT (Low-Voltage TTL) logic family, designed specifically for high-speed, low-power bidirectional bus interfacing in mixed-voltage systems bridging 3.3V and 5V domains.

FAQ

What is the function of the T/R pin on the 74LVT2245MTCX?

The T/R (Transmit/Receive) pin controls data direction in the 74LVT2245MTCX: when HIGH, it enables unidirectional data flow from A-port inputs to B-port outputs; when LOW, it enables reverse flow from B-port inputs to A-port outputs. This single-pin control simplifies bus arbitration logic and eliminates need for separate direction-control registers in microcontroller firmware.

Does the 74LVT2245MTCX support live insertion in backplane systems?

Yes, the 74LVT2245MTCX supports live insertion/extraction due to its power-up/down high-impedance feature. During power transitions, both A and B ports enter a high-Z state automatically, preventing bus contention or signal corruption when modules are added or removed from powered backplanes-critical for telecom and industrial chassis applications.

What is the purpose of the 25Ω series resistor on the B-port outputs of the 74LVT2245MTCX?

The 25Ω series resistor integrated into each B-port output of the 74LVT2245MTCX serves to dampen signal reflections and reduce overshoot/undershoot on PCB traces, especially in unterminated or lightly loaded transmission lines. It eliminates need for eight discrete surface-mount resistors, saving board area and improving signal integrity in high-speed bus applications up to 100MHz.

Can the 74LVT2245MTCX interface directly with 5V TTL logic?

Yes, the 74LVT2245MTCX accepts input voltages up to 5.5V while operating from a 3.3V supply, enabling direct connection to 5V TTL outputs without external level-shifting circuitry. Its input thresholds (VIH = 2.0V min, VIL = 0.8V max) are fully compatible with standard TTL logic levels, making it ideal for bridging legacy and modern voltage domains.

How does the Output Enable (OE) pin affect both A and B ports in the 74LVT2245MTCX?

The OE (Output Enable) pin on the 74LVT2245MTCX is active-HIGH and simultaneously places all A0–A7 and B0–B7 pins into high-impedance state when asserted, regardless of T/R state. This global disable function allows centralized bus arbitration, enabling multiple transceivers to share a common data path without contention-essential in multi-master or daisy-chained topologies.