onsemi 74ALVCH245WMX

Overview

74ALVCH245WMX from Fairchild Semiconductor is a low-voltage bidirectional transceiver with bushold circuitry, designed for 1.65V–3.6V bus interface applications. It features eight non-inverting channels, 3-STATE outputs controlled by OE and T/R inputs, and eliminates external pull-up resistors via active bushold on all A/B port data lines. Used in voltage-scalable digital subsystems such as memory expansion and microcontroller peripheral buses.

For engineers reviewing the 74ALVCH245WMX datasheet, pinout, applications, or equivalent options, key selection criteria include VCC operating range (1.65–3.6V), propagation delay (3.6 ns max at 3.3V), bushold input current specs, 3-STATE enable/disable timing, and SOIC-20 package compatibility.

Technical Context

The 74ALVCH245WMX implements dual-bus bidirectional data transfer using a single directional control (T/R) and global output enable (OE) signal. Its bushold circuitry actively maintains valid logic levels on floating A0–A7 and B0–B7 inputs without external biasing, supporting hot-swap and partial-power-down scenarios.

It operates across three VCC voltage bands-1.65–1.95V, 2.3–2.7V, and 2.7–3.6V-with distinct AC timing specifications per band. Propagation delay (tPHL/tPLH) degrades predictably with lower supply voltage: 6.0 ns max at 1.8V, 4.2 ns at 2.5V, and 3.6 ns at 3.3V.

Key Specifications

Pinout & Package

74ALVCH245WMX is packaged in a 20-lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300" wide (Package Number M20B). Body dimensions: 12.8 mm × 7.5 mm × 2.35 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AVCH245RHLR and 74LVC245ABQ, the 74ALVCH245WMX uniquely delivers bushold functionality in a standard SOIC-20 package, simplifying design for systems with intermittent or undefined I/O states-especially in legacy-compatible upgrades and modular backplanes.

Availability

74ALVCH245WMX is available at Aetrix Electronics and suitable for memory expansion interfaces, microcontroller peripheral buses, hot-swappable module interfaces, and industrial control backplanes requiring stable component supply and long-term obsolescence management.

Supply support for 74ALVCH245WMX 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 analog and power IC manufacturer acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and computing infrastructure.

The ALVCH family was engineered for low-voltage, high-speed bus interfacing in mixed-supply systems, emphasizing noise immunity, input stability, and drop-in compatibility with earlier 74-series logic.

FAQ

What is the maximum propagation delay of the 74ALVCH245WMX at 3.3V supply?

The 74ALVCH245WMX has a maximum propagation delay (tPHL/tPLH) of 3.6 ns when VCC = 3.0V to 3.6V, as specified in the AC Electrical Characteristics table. This value applies under load conditions of CL = 50 pF and RL = 500 Ω, making it suitable for high-speed 25+ MHz bus applications. The 74ALVCH245WMX achieves this performance while maintaining low dynamic power consumption typical of advanced CMOS processes.

Does the 74ALVCH245WMX require external pull-up resistors on its data lines?

No, the 74ALVCH245WMX does not require external pull-up or pull-down resistors due to integrated bushold circuitry on all A0–A7 and B0–B7 inputs. This feature actively maintains the last valid logic state on floating inputs, eliminating bus uncertainty during power-up, hot-swap, or tri-state transitions. The 74ALVCH245WMX specifies bushold drive current (±75 µA at 3.0V) to ensure robust hold strength across its full VCC range.

What package type is used for the 74ALVCH245WMX?

The 74ALVCH245WMX uses a 20-lead Small Outline Integrated Circuit (SOIC) package, JEDEC MS-013 compliant, 0.300" wide (Package Number M20B). Its body dimensions are 12.8 mm × 7.5 mm × 2.35 mm, with standard 1.27 mm lead pitch. This through-hole-compatible surface-mount package supports automated assembly and offers proven thermal and mechanical reliability in industrial environments.

Can the 74ALVCH245WMX operate at 1.8V supply voltage?

Yes, the 74ALVCH245WMX is fully specified to operate at 1.65V to 3.6V VCC, including 1.8V ± 0.15V. At 1.8V, its maximum propagation delay is 6.0 ns (CL = 50 pF), and bushold current is ±75 µA at VIN = 0.8V/2.0V. All DC and AC parameters-including VIH/VIL thresholds, VOL/VOH levels, and 3-STATE leakage-are guaranteed across this range, enabling seamless integration into dual-voltage 1.8V/3.3V systems without level translation.

How does the OE and T/R control logic work in the 74ALVCH245WMX?

In the 74ALVCH245WMX, OE (pin 1) is an active-low global enable: when HIGH, both A and B ports enter high-impedance regardless of T/R state. When OE is LOW, T/R (pin 19) determines direction-LOW enables B→A data flow, HIGH enables A→B. This two-signal control allows precise bus arbitration and prevents contention. The 74ALVCH245WMX truth table confirms that OE takes precedence, ensuring fail-safe isolation during system reset or configuration.