Texas Instruments SN74AHC157QWBQBRQ1

Overview

SN74AHC157QWBQBRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive-qualified quad 2-to-1 data selector/multiplexer with true outputs, operating from 2 V to 5.5 V, delivering 12 ns propagation delay at 5 V/50 pF, and featuring a common active-low strobe (G) input for simultaneous output disable. It routes four independent 2-input data channels in memory selection and bus multiplexing applications.

For engineers reviewing the SN74AHC157QWBQBRQ1 datasheet, SN74AHC157QWBQBRQ1 pinout, SN74AHC157QWBQBRQ1 application, or SN74AHC157QWBQBRQ1 equivalent, this page provides verified functional modes, automotive-grade thermal and ESD specs, WQFN wettable flank package details, and real-world routing use cases - all confirmed against TI's SCLSA06 production datasheet.

Technical Context

The SN74AHC157QWBQBRQ1 implements four independent CMOS 2:1 multiplexers sharing one address select (A/B) and one active-low strobe (G). When G is high, all Y outputs are forced low regardless of A/B or data inputs; when G is low, each Y output equals the selected input (1A/1B, 2A/2B, etc.) per the A/B state. All outputs are true (non-inverted), push-pull, and capable of ±8 mA drive at 5 V.

It uses standard CMOS inputs with ≤10 pF input capacitance and balanced output drivers optimized for low-noise, high-speed switching into ≤50 pF loads. The device supports asynchronous operation across –40°C to +125°C ambient, with latch-up immunity >250 mA per JESD17 and HBM/CDM ESD ratings of ±2 kV / ±1 kV.

Key Specifications

Pinout & Package

SN74AHC157QWBQBRQ1 is packaged in a 16-pin wettable flank QFN (WBQB), 3.5 mm × 2.5 mm body size, with exposed thermal pad (connected to GND or left floating). The package supports AOI-compatible side-fillet inspection and enhanced thermal dissipation (RθJA = 105.6°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LV157AQPWRQ1 and MC74VHC157DTG, the SN74AHC157QWBQBRQ1 uniquely combines AEC-Q100 Grade 1 qualification, wettable flank QFN packaging, and 12 ns speed at 5 V - making it the only option qualified for production deployment in safety-relevant powertrain and chassis modules.

Availability

SN74AHC157QWBQBRQ1 is available at Aetrix Electronics and suitable for automotive ECU design, ADAS sensor fusion subsystems, and body control module development requiring stable component supply, full AEC-Q100 compliance, and long-term lifecycle support.

Supply support for SN74AHC157QWBQBRQ1 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 automotive ICs, with decades of experience in automotive-grade logic and interface solutions.

The SN74AHC157QWBQBRQ1 belongs to TI's AHC logic family designed specifically for high-speed, low-power, automotive-qualified data routing - targeting ECU, infotainment, and ADAS subsystems where reliability and signal fidelity are critical.

FAQ

What is the maximum capacitive load SN74AHC157QWBQBRQ1 can drive while meeting datasheet timing specs?

The SN74AHC157QWBQBRQ1 is characterized and guaranteed to meet all switching specifications - including 12 ns propagation delay at 5 V - with a load capacitance of up to 50 pF. Driving larger loads increases delay and may degrade noise margins; TI recommends limiting total output capacitance to 50 pF unless derating curves from Section 5.6 are applied. Layout best practices include short traces and local decoupling to maintain performance.

Does SN74AHC157QWBQBRQ1 support partial power-down or I/O isolation when VCC is unpowered?

No, SN74AHC157QWBQBRQ1 does not support I/O isolation during power-down. Its CMOS inputs and outputs are not 5-V tolerant when VCC = 0 V, and applying signals to any pin with VCC unpowered violates Absolute Maximum Ratings (VI must stay within –0.5 V to VCC + 0.5 V). To prevent damage, ensure all inputs are held at GND or use external isolation switches if interfacing with live buses during power sequencing.

How is the thermal pad on SN74AHC157QWBQBRQ1 intended to be connected on the PCB?

The thermal pad on SN74AHC157QWBQBRQ1 should be connected to the GND plane using multiple thermal vias (≥4, 0.3 mm diameter) for optimal heat dissipation and EMI suppression. TI's datasheet explicitly states it may be left floating, but grounding is strongly recommended to reduce junction temperature - especially in high-ambient automotive environments where RθJA drops from 105.6°C/W (ungrounded) to ~75°C/W (properly grounded).

Can unused inputs on SN74AHC157QWBQBRQ1 be left floating?

No - unused inputs on SN74AHC157QWBQBRQ1 must never be left floating. As a CMOS device, floating inputs cause undefined logic states, increased ICC, oscillation, and potential device damage. TI mandates termination to either VCC or GND via direct connection or a 10 kΩ pull-up/down resistor. For example, unused A/B or G inputs should be tied to GND to ensure deterministic disable behavior.

What is the function of the strobe (G) input on SN74AHC157QWBQBRQ1, and how does it interact with the address select (A/B)?

The strobe (G) input on SN74AHC157QWBQBRQ1 is an active-low global enable: when G = HIGH, all four Y outputs are forced LOW regardless of A/B state or data inputs - providing hardware-level bus isolation. When G = LOW, the A/B input determines which of the two data sources (A or B) is routed to each Y output. This two-level control enables glitch-free arbitration in shared-bus architectures.