Texas Instruments SN74AHCT157DBR

Overview

SN74AHCT157DBR from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer IC designed for 4.5V–5.5V V_CC operation in automotive and industrial digital logic systems. It features a common active-low strobe (G), true-data outputs, TTL-voltage-compatible inputs, and supports 4-bit parallel data routing with latch-up performance exceeding 250 mA per JESD17.

For engineers reviewing the SN74AHCT157DBR datasheet, SN74AHCT157DBR pinout, SN74AHCT157DBR application, or SN74AHCT157DBR equivalent, this device serves as a high-reliability, low-power multiplexing solution for bus selection, signal routing, and data path control in 5V logic environments with strict timing and noise immunity requirements.

Technical Context

The SN74AHCT157DBR implements four independent 2:1 multiplexers sharing a single active-low enable (G) input. When G is high, all Y outputs are forced low; when G is low, each Y output selects between its corresponding A and B inputs based on the shared A/B select line. The device operates strictly in positive-logic mode with no internal latching-output state follows input changes within specified propagation delays.

Its electrical behavior is defined by guaranteed VOH ≥3.8 V at I_OH = –8 mA and VOL ≤0.44 V at I_OL = 8 mA over –40°C to +85°C, with input thresholds fixed at VIH = 2.0 V and VIL = 0.8 V. Switching performance is characterized at CL = 15 pF and CL = 50 pF, delivering t_PLH/t_PHL ≤7.5 ns (15 pF) and ≤10 ns (50 pF) for G→Y paths.

Key Specifications

Pinout & Package

SN74AHCT157DBR uses a 16-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch, body size 5.0 mm × 4.4 mm, and maximum height 2.0 mm. Pin 1 is located in quadrant Q1 per tape-and-reel specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT157DR and SN74LVC157APWR, the SN74AHCT157DBR uniquely balances 5V TTL interoperability, SSOP space efficiency, and industrial temperature support-making it optimal for cost-sensitive, high-volume 5V logic upgrades where board area and legacy interface retention are critical.

Availability

SN74AHCT157DBR is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and test equipment requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for SN74AHCT157DBR 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 digital ICs.

The SN74AHCT logic family was engineered for seamless 5V TTL-to-CMOS interfacing in industrial control and automotive subsystems-delivering speed, noise immunity, and consistent parametric performance across temperature extremes.

FAQ

What is the function of the A/B pin on the SN74AHCT157DBR?

The A/B pin (Pin 1) is a global select line that determines which input pair-A or B-is routed to all four Y outputs. When A/B is low, the A inputs (1A–4A) appear at outputs 1Y–4Y; when high, the B inputs (1B–4B) are selected. This single-line control simplifies synchronization across all four channels in the SN74AHCT157DBR.

Does the SN74AHCT157DBR require external pull-up or pull-down resistors on unused inputs?

Yes-per TI's design guidance, all unused inputs of the SN74AHCT157DBR must be terminated to either V_CC or GND to prevent floating states that cause increased ICC, noise susceptibility, or undefined outputs. For example, an unused A/B select line should be tied to GND to default to A-input selection, ensuring deterministic behavior in the SN74AHCT157DBR.

Can the SN74AHCT157DBR operate reliably at 4.5V supply voltage?

Yes-the SN74AHCT157DBR is fully specified from 4.5 V to 5.5 V per its Recommended Operating Conditions. At V_CC = 4.5 V, it maintains VOH ≥3.94 V (I_OH = –8 mA) and VOL ≤0.44 V (I_OL = 8 mA), with propagation delays increasing only marginally (≤10% vs. 5V), confirming robust functionality across the entire rated SN74AHCT157DBR supply range.

What is the maximum capacitive load the SN74AHCT157DBR can drive while meeting timing specs?

The SN74AHCT157DBR switching characteristics are guaranteed up to 50 pF load capacitance, with t_PLH/t_PHL ≤10 ns (G→Y) and ≤12 ns (A/B→Y). Driving loads beyond 50 pF will increase delay nonlinearly and may violate setup/hold margins in synchronous systems-designers should verify timing margins using the SN74AHCT157DBR's published CL-dependent delay curves.

Is the SN74AHCT157DBR pin-compatible with the SN74AHCT157PW (TSSOP)?

No-SN74AHCT157DBR (SSOP-16) and SN74AHCT157PW (TSSOP-16) share identical pin functions and numbering but differ in physical dimensions, pitch (0.65 mm vs. 0.65 mm), and body size (5.0 × 4.4 mm vs. 5.0 × 6.4 mm). While both are 16-pin surface-mount packages, their land patterns and solder paste stencils are not interchangeable; PCB layout must match the specific SN74AHCT157DBR mechanical outline.