Texas Instruments SN74LVC2G157DCUR

Overview

SN74LVC2G157 from Texas Instruments is a single 2-line to 1-line data selector multiplexer with true and complementary outputs (Y and Y), designed for 1.65-V to 5.5-V V_CC operation, supporting 5-V tolerant inputs up to 5.5 V, delivering 6 ns max propagation delay at 3.3 V, ±24-mA output drive, and I_off support for live insertion in partial-power-down systems - used in sensor multiplexing on embedded PC and HVAC control boards.

For engineers reviewing the SN74LVC2G157 datasheet, SN74LVC2G157 pinout, SN74LVC2G157 application, or SN74LVC2G157 equivalent, key selection criteria include its dual-output (true/inverted) configuration, 5.5-V input tolerance enabling level translation, low ICC (10 µA max), NanoFree™ VSSOP-8 package footprint, and guaranteed I_off behavior for back-drive protection during power sequencing.

Technical Context

The SN74LVC2G157 implements a positive-logic 2:1 multiplexer with active-low common strobe (G): when G = HIGH, both outputs are forced (Y = LOW, Y = HIGH); when G = LOW, the A/B select line routes either A or B to Y (non-inverted) and Y (inverted). Its standard CMOS inputs accept 0–5.5 V regardless of V_CC, enabling down-translation from 5-V sources to lower-voltage logic domains.

It features balanced high-drive CMOS push-pull outputs capable of ±24 mA at 3.3 V, with specified VOLP < 0.8 V and VOHV > 2 V (V_CC = 3.3 V, T_A = 25°C), and integrated negative clamping diodes on all I/O pins per JESD 22. I_off circuitry ensures outputs enter high-impedance state when V_CC = 0, preventing current backflow during hot-swap or partial power-down.

Key Specifications

Pinout & Package

SN74LVC2G157DCUR uses the 8-pin VSSOP (DCU) package, measuring 2.30 mm × 2.00 mm, with 0.5-mm lead pitch and exposed pad-less construction optimized for space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC2G157DCUR, SN74LVC1G157DBVR saves area but sacrifices design flexibility from missing Y output, while 74LVC2G53DP,122 adds analog capability at the cost of increased complexity in digital-only control paths and no native I_off-enabled disable.

Availability

SN74LVC2G157DCUR is available at Aetrix Electronics and suitable for embedded PC, HVAC field transmitters, and barcode scanner designs requiring stable component supply, long-term manufacturability, and industrial-grade ESD robustness.

Supply support for SN74LVC2G157DCUR 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 logic solutions, with over 50 years of innovation in high-reliability interface and signal-path components.

The SN74LVC2G157 belongs to TI's LVC logic family, engineered for low-voltage, high-speed, mixed-signal interfacing in space- and power-constrained applications including portable instrumentation and industrial automation.

FAQ

What is the function of the G (strobe) pin on the SN74LVC2G157DCUR?

The G pin is an active-HIGH common strobe that globally disables data routing: when G = HIGH, Y is forced LOW and Y is forced HIGH regardless of A/B or input states. This provides hardware-level output override for system reset, fault isolation, or power sequencing - a feature not present in basic 2:1 muxes like SN74LVC1G157. The SN74LVC2G157DCUR uses this to ensure deterministic outputs during initialization or error conditions.

Can the SN74LVC2G157DCUR translate 5-V signals to a 1.8-V system?

Yes. The SN74LVC2G157DCUR accepts input voltages up to 5.5 V independent of V_CC, so it can safely interface 5-V sensors or controllers to a 1.8-V domain when powered at V_CC = 1.8 V. Its outputs swing rail-to-rail (0 V to 1.8 V), making it a true down-translator. This behavior is explicitly confirmed in the TI datasheet Section 8.3 and eliminates need for external voltage translators in the SN74LVC2G157DCUR signal path.

Does the SN74LVC2G157DCUR support hot-swap or live insertion?

Yes. The SN74LVC2G157DCUR incorporates I_off circuitry that disables outputs and limits leakage to ±10 µA when V_CC = 0, preventing back-current flow from live backplanes into unpowered circuitry. This is validated per JESD 78 Class II latch-up testing and is critical for modular systems like server PSUs or industrial I/O cards where the SN74LVC2G157DCUR may be inserted while other rails remain active.

What is the maximum capacitive load the SN74LVC2G157DCUR can drive while maintaining 6 ns t_pd?

The SN74LVC2G157DCUR maintains its 6 ns max t_pd specification with a 50-pF load at V_CC = 3.3 V, as defined in the Switching Characteristics table. Driving >50 pF increases propagation delay nonlinearly; TI recommends limiting total load to ≤70 pF for reliable operation. This includes PCB trace capacitance, probe effects, and receiver input capacitance - all summed in the SN74LVC2G157DCUR signal path.

How does the SN74LVC2G157DCUR differ from the SN74LVC2G157DCT in terms of thermal performance?

The SN74LVC2G157DCUR (VSSOP-8) has a junction-to-ambient thermal resistance (R_θJA) of 289.9°C/W, versus 192.0°C/W for the SN74LVC2G157DCT (SSOP-8). While the DCUR saves board area, its higher R_θJA means greater temperature rise under identical power dissipation. For continuous 24-mA output loads, derating or local airflow may be needed - a key thermal trade-off in the SN74LVC2G157DCUR's compact packaging.