Texas Instruments SN74AHCT157PW

Overview

SN74AHCT157PW from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer IC operating at 4.5V–5.5V V_CC, featuring TTL-compatible inputs, active-low strobe (G), true outputs, and 16-pin TSSOP packaging. It routes one of two 4-bit input sources to four outputs based on address select (A/B) and enables/disables all outputs via G. Used in digital logic signal routing for microcontroller I/O expansion and bus arbitration.

For engineers reviewing the SN74AHCT157PW datasheet, SN74AHCT157PW pinout, SN74AHCT157PW application, or SN74AHCT157PW equivalent, this page delivers verified electrical specs (t_PLH/t_PHL ≤ 9.5 ns @ 5V/15pF), thermal resistance (R_θJA = 135.9°C/W), supply current (I_CC ≤ 20 μA), noise immunity (V_IL = 0.8 V, V_IH = 2 V), and package dimensions (5 mm × 6.4 mm).

Technical Context

The SN74AHCT157PW implements four independent 2:1 multiplexers sharing a common active-low strobe (G) and address select (A/B). When G is high, all Y outputs are forced low regardless of A/B or data inputs; when G is low, each Y output reflects the selected input (A or B) per channel. The device uses positive-logic CMOS architecture with TTL-voltage-compatible input thresholds.

All inputs tolerate 0–5.5 V, outputs drive ±8 mA at V_OH ≥ 3.8 V and V_OL ≤ 0.44 V under load, and propagation delay is specified across temperature (–40°C to +85°C) and load capacitance (15 pF and 50 pF). Latch-up performance exceeds 250 mA per JESD17.

Key Specifications

Pinout & Package

TSSOP-16 (PW) package: 5.0 mm × 6.4 mm body size, 1.2 mm max height, 0.65 mm lead pitch, gull-wing leads, RoHS-compliant NiPdAu/Sn finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT157PWR, SN74AHCT157PW shares identical functionality and layout but lacks tape-and-reel support; versus SN74LVC157APW, it provides guaranteed 5 V operation and TTL compatibility at the cost of slightly higher propagation delay - critical for backward-compatible industrial upgrades.

Availability

SN74AHCT157PW is available at Aetrix Electronics and suitable for industrial control systems, test equipment signal routing, and legacy system interface adapters requiring stable component supply and long-term obsolescence management.

Supply support for SN74AHCT157PW 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 founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial, automotive, and consumer reach.

The SN74AHCT157PW belongs to TI's 74AHCT logic family, engineered for 5 V systems requiring TTL compatibility, low power, and robust latch-up immunity - targeting industrial automation, instrumentation, and legacy interface bridging.

FAQ

What is the maximum operating temperature for the SN74AHCT157PW?

The SN74AHCT157PW is rated for operation from –40°C to +85°C ambient temperature. This industrial-grade range is validated per TI's recommended operating conditions and supported by thermal characterization (R_θJA = 135.9°C/W). Operation beyond +85°C risks exceeding junction temperature limits and violating parametric specifications - derating or enhanced cooling is required above this point. The SN74AHCT157PW datasheet specifies no extended temperature variants.

Does the SN74AHCT157PW support 3.3 V logic inputs?

No, the SN74AHCT157PW does not reliably support 3.3 V logic inputs as valid HIGH signals. Its V_IH threshold is fixed at 2.0 V minimum across the full temperature range, but this is specified only for V_CC = 4.5–5.5 V operation. At 3.3 V V_CC, the device is outside its recommended operating conditions and may exhibit undefined behavior. For 3.3 V systems, use SN74LVC157APW instead - the SN74AHCT157PW is strictly a 5 V logic device.

Can unused inputs on the SN74AHCT157PW be left floating?

No, unused inputs on the SN74AHCT157PW must not be left floating. TI explicitly requires all unused inputs to be tied to V_CC or GND to prevent undefined logic states, increased power consumption, and potential oscillation. Floating inputs cause partial turn-on of internal CMOS structures, raising I_CC and degrading noise immunity. The SN74AHCT157PW datasheet cites SCBA004 for guidance - tie A/B, G, or any unused data inputs to a defined rail using pull-up/pull-down resistors or direct connection.

What is the output drive capability of the SN74AHCT157PW?

The SN74AHCT157PW provides ±8 mA output drive per Y pin at V_CC = 5 V, with V_OH ≥ 3.8 V (I_OH = –8 mA) and V_OL ≤ 0.44 V (I_OL = 8 mA). This meets standard 74-series fan-out requirements (driving up to 10 LS-TTL loads) and supports direct connection to LEDs with appropriate current-limiting resistors. Exceeding ±8 mA risks violating VOH/VOL specs or triggering latch-up - verify load current in final design using the SN74AHCT157PW typical characteristics curves.

Is there a pin-compatible automotive-grade version of the SN74AHCT157PW?

Yes, the SN74AHCT157-Q1 is the AEC-Q100 qualified automotive variant of the SN74AHCT157PW. It shares identical pinout, functionality, and 5 V operation but is tested for –40°C to +125°C operation, enhanced ESD robustness (HBM ≥ 2 kV), and zero-defect reliability per automotive standards. The SN74AHCT157-Q1 uses the same TSSOP-16 (PW) package and is intended for ADAS sensors, body control modules, and infotainment interfaces - it is not a drop-in replacement for SN74AHCT157PW in non-automotive designs due to qualification overhead and cost.