Texas Instruments 74LVC2G157DCURG4

Overview

74LVC2G157DCURG4 from Texas Instruments is a single 2-line to 1-line data selector multiplexer with true and complementary outputs (Y and Y), common strobe (G) control, and operation across 1.65 V to 5.5 V supply. It delivers 6 ns max propagation delay at 3.3 V, ±24 mA output drive, and Ioff support for live insertion in partial-power-down systems. Used in sensor multiplexing on embedded PC and HVAC controller boards.

For engineers reviewing the 74LVC2G157DCURG4 datasheet, 74LVC2G157DCURG4 pinout, 74LVC2G157DCURG4 application, or 74LVC2G157DCURG4 equivalent, key selection criteria include VCC range compatibility (1.65–5.5 V), dual-output logic state behavior under strobe control, Ioff-enabled back-drive protection, and VSSOP-8 package suitability for space-constrained signal routing.

Technical Context

The 74LVC2G157DCURG4 implements a positive-logic 2:1 multiplexer with active-low strobe (G): when G = LOW, output Y mirrors selected input (A or B per A/B control), while Y provides inversion; when G = HIGH, both outputs are forced static (Y = LOW, Y = HIGH). Its standard CMOS inputs accept up to 5.5 V regardless of VCC, enabling level translation from higher-voltage sources down to the local rail.

It features balanced high-drive push-pull outputs capable of sourcing/sinking ±24 mA at 3.3 V, with ground bounce (VOLP) < 0.8 V and VOH undershoot (VOHV) > 2 V under typical conditions. The Ioff circuit disables outputs during power-down, blocking current flow between powered and unpowered sections of the system.

Key Specifications

Pinout & Package

VSSOP-8 (DCU) package: 2.30 mm × 2.00 mm, 0.5-mm pitch, thin-profile surface-mount design optimized for high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC1G157DBVR, the 74LVC2G157DCURG4 provides full dual-output capability in a standardized 8-pin VSSOP, while the 74LVC2G157GM,115 offers superior size reduction at the expense of slightly lower thermal efficiency - making the 74LVC2G157DCURG4 optimal for designs requiring both Y and Y with proven manufacturability and thermal headroom.

Availability

74LVC2G157DCURG4 is available at Aetrix Electronics and suitable for embedded PC sensor hubs, HVAC field transmitters, and network-attached storage (NAS) fan control systems requiring stable component supply and long-term industrial lifecycle support.

Supply support for 74LVC2G157DCURG4 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 company specializing in analog, embedded processing, and logic solutions, with leadership in industrial, automotive, and communications markets.

The SN74LVC2G157 belongs to TI's LVC low-voltage CMOS logic family, designed for robust signal routing in mixed-voltage embedded systems where level translation, low power, and small footprint are essential.

FAQ

What is the function of the G (strobe) pin on the 74LVC2G157DCURG4?

The G pin is an active-low common strobe input. When G = HIGH, both outputs are forced static: Y = LOW and Y = HIGH, regardless of A, B, or A/B states. When G = LOW, the device operates as a standard 2:1 multiplexer, routing either A or B to Y (and its inverse to Y) based on the A/B select input. This enables global enable/disable control across multiple signal paths.

Does the 74LVC2G157DCURG4 support level translation, and how does it work?

Yes, the 74LVC2G157DCURG4 supports down-translation: its inputs tolerate up to 5.5 V regardless of VCC level (1.65–5.5 V). For example, with VCC = 1.8 V, 5-V sensor signals applied to A, B, or A/B are safely accepted and correctly interpreted, allowing direct interfacing with legacy 5-V peripherals without external translators - a key feature confirmed in TI's datasheet Section 8.3.

What is the maximum capacitive load the 74LVC2G157DCURG4 can drive while meeting timing specs?

The 74LVC2G157DCURG4 is characterized for loads ≤50 pF in switching specifications (Section 6.6), and application guidance recommends staying ≤70 pF for reliable operation. Exceeding 70 pF increases propagation delay and may cause signal integrity issues due to slower edge rates; layout best practices advise short, low-inductance traces and proper decoupling to maintain timing margins.

How does Ioff functionality protect the 74LVC2G157DCURG4 during partial power-down?

Ioff disables the outputs when VCC = 0 V, limiting leakage current to ±10 µA maximum. This prevents back-driving current from powered sections (e.g., 5-V sensor lines) into unpowered logic rails, protecting both the 74LVC2G157DCURG4 and upstream components during hot-swap or staged power sequencing - a requirement verified in JESD78 Class II latch-up testing and explicitly documented in TI's datasheet Sections 1 and 8.1.

Can unused inputs on the 74LVC2G157DCURG4 be left floating?

No. All unused inputs (A, B, A/B, or G) must be terminated to either VCC or GND using a pull-up or pull-down resistor - typically 10 kΩ - to prevent undefined logic states, oscillation, or excessive current draw. TI's datasheet Section 11.1 and application note SCBA004 explicitly require this for CMOS inputs; floating inputs violate recommended operating conditions and risk functional failure.