STMicroelectronics 74LCX157MTR

Overview

74LCX157MTR from STMicroelectronics is a low-voltage CMOS quad 2-channel non-inverting multiplexer with 5V-tolerant inputs, operating from 2.0V to 3.6V supply, delivering tPD = 6.0ns (max) at VCC = 3V, ±24mA output drive, and pin/function compatibility with standard 74-series 157 devices. It routes four independent A/B data pairs to Y outputs under common SELECT and STROBE control, used in 3.3V logic interfacing with 5V legacy buses.

For engineers reviewing the 74LCX157MTR datasheet, 74LCX157MTR pinout, 74LCX157MTR application, or 74LCX157MTR equivalent, key selection criteria include 5V-tolerant input handling, symmetrical 24mA drive capability at 3V, balanced tPLH/tPHL propagation delays, PCI bus-level output compliance, and power-down protection on all I/Os.

Technical Context

The device implements four independent 2:1 multiplexers sharing one SELECT line and one active-low STROBE enable. When STROBE is high, all Y outputs are forced low regardless of SELECT or input states - enabling clean bus isolation during power-down or reset sequences.

Its C2MOS sub-micron fabrication ensures latch-up immunity >500mA (JESD17) and ESD robustness (HBM >2kV, MM >200V), while symmetrical |IOH| = IOL = 24mA (min) at VCC = 3V supports bidirectional signal integrity in mixed-voltage interconnects.

Key Specifications

Pinout & Package

74LCX157MTR is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package per JEDEC MS-012, with 1.27mm pitch and body dimensions 9.8 × 5.8 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2:1 multiplexer applications.

Compared with 74LVC157PW and SN74LVCH162374DGGR, the 74LCX157MTR uniquely combines 5V-tolerant inputs, power-down I/O protection, and guaranteed ±24mA drive at 3V - making it optimal for robust, mixed-voltage bus interface applications requiring fail-safe isolation.

Availability

74LCX157MTR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, PCI add-in card design, low-power embedded test interfaces, and mixed-voltage FPGA configuration buses requiring stable component supply across extended temperature ranges (–55°C to +125°C).

Supply support for 74LCX157MTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, analog ICs, power management devices, and discrete components for industrial, automotive, and consumer markets.

The 74LCX logic family was engineered specifically for high-speed, low-voltage 3.3V system interfacing with backward compatibility to 5V environments - targeting PCI, embedded control, and portable electronics where power efficiency and voltage translation are critical.

FAQ

Is 74LCX157MTR pin-compatible with standard 74HC157?

Yes - it is pin- and function-compatible with 74HC157 and 74LS157, including identical pin numbering and truth table behavior. However, its 5V-tolerant inputs and 3.3V-only supply require external level shifting if used in a 5V system without VCC = 5V, which this device does not support.

What happens to outputs when VCC = 0V?

When VCC drops to 0V, the 74LCX157MTR enters power-down mode: all I/O pins exhibit high-impedance behavior with ≤10µA off-state leakage (Ioff), preventing back-driving of connected circuitry and eliminating unintended current paths in partially powered systems.

Can STROBE be left unconnected in normal operation?

No - STROBE must be actively driven low to enable multiplexer operation. Leaving it floating risks undefined output states due to noise coupling; it should be tied to GND via a pull-down resistor or controlled by a system enable signal to ensure deterministic behavior.

Does 74LCX157MTR support hot-swap insertion?

Yes - its power-down protection, 5V-tolerant inputs, and latch-up immunity (>500mA per JESD17) allow safe insertion into live backplanes. However, STROBE must be held high until VCC stabilizes to prevent transient output glitches during power ramp-up.