Texas Instruments SN74AHCT157NS

Overview

SN74AHCT157NS from Texas Instruments is a quadruple 2-line to 1-line data selector/multiplexer IC operating at 4.5 V–5.5 V, featuring TTL-compatible inputs, a common strobe (G) control, true-data output logic, and 16-pin SOP-NS package. It routes one of two 4-bit input sources to four outputs based on select line state, used in digital bus routing and address/data path selection.

For engineers reviewing the SN74AHCT157NS datasheet, SN74AHCT157NS pinout, SN74AHCT157NS application, or SN74AHCT157NS equivalent, key selection criteria include propagation delay (≤9.5 ns @ 50 pF), output drive capability (±8 mA), latch-up immunity (>250 mA), and compatibility with 5-V TTL and CMOS logic families in industrial control and embedded interface designs.

Technical Context

The SN74AHCT157NS implements four independent 2:1 multiplexers sharing a single active-low strobe (G) and a common select input (A/B). When G is high, all Y outputs are forced low; when G is low, each Yn follows the selected input (An or Bn) per A/B state. The device uses standard CMOS silicon with TTL-level input thresholds (VIH = 2 V, VIL = 0.8 V).

It operates strictly within 4.5–5.5 V supply range and supports 50-pF load switching with tPLH/tPHL ≤9.5 ns for data paths and ≤12 ns for strobe-controlled enable/disable transitions. Input transition rate is specified at 20 ns/V, ensuring robust timing margin against slow edges.

Key Specifications

Pinout & Package

The SN74AHCT157NS is housed in a 16-pin SOP (Small Outline Package) with NS suffix, measuring 10.3 mm × 5.3 mm × 1.95 mm (JEDEC MO-153 compliant), gull-wing leads, and RoHS-compliant green finish (Pb-free, no Sb/Br).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit 2:1 multiplexer applications.

Compared with SN74HC157N and 74LVC157APW, the SN74AHCT157NS uniquely balances 5-V TTL compatibility, 9.5-ns timing, and ±8-mA drive-making it the optimal choice for industrial 5-V bus expansion where interoperability and timing margin are critical.

Availability

SN74AHCT157NS is available at Aetrix Electronics and suitable for industrial PLC I/O modules, microcontroller-based test equipment, legacy bus interface bridges, and digital instrumentation requiring stable component supply across extended temperature ranges.

Supply support for SN74AHCT157NS 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 technologies, with decades of experience delivering high-reliability components for industrial, automotive, and communications markets.

The SN74AHCT157NS belongs to TI's AHCT logic family-designed specifically for 5-V TTL-to-CMOS bridging in industrial control, test instrumentation, and legacy system upgrades where speed, noise immunity, and robustness are essential.

FAQ

What is the supply voltage range for the SN74AHCT157NS?

The SN74AHCT157NS operates over a supply voltage range of 4.5 V to 5.5 V. This narrow 5-V-centric range ensures compatibility with standard TTL logic families and guarantees specified performance-including propagation delay, output drive, and noise margins-only within this window. Operation outside this range may result in undefined behavior or reduced reliability.

Does the SN74AHCT157NS support 3.3-V input logic levels?

No, the SN74AHCT157NS does not reliably accept 3.3-V logic inputs. Its input thresholds are TTL-compatible (VIH = 2.0 V min, VIL = 0.8 V max), meaning a 3.3-V high signal meets VIH but lacks sufficient margin for noise immunity in industrial settings. For guaranteed interoperability with 3.3-V systems, level translation or a 3.3-V logic family like 74LVC157 is required.

What is the function of the G (strobe) pin on the SN74AHCT157NS?

The G pin on the SN74AHCT157NS is an active-low strobe that globally disables all four outputs. When G is high, all Y1–Y4 outputs are forced low regardless of A/B or data inputs. When G is low, the device performs normal 2:1 multiplexing per the A/B select state. This enables synchronized enable/disable of the entire 4-bit path in timing-critical applications.

Can the SN74AHCT157NS drive standard TTL loads directly?

Yes, the SN74AHCT157NS can directly drive standard TTL loads. Its specified output drive is ±8 mA at VCC = 4.5 V, exceeding the –1.6 mA (high) and 16 mA (low) requirements of legacy 74LS TTL inputs. This allows fan-out of up to five 74LS inputs per output without external buffers, simplifying interconnect in mixed-logic systems.

Is the SN74AHCT157NS pin-compatible with other 16-pin multiplexers like the SN74LS157?

Yes, the SN74AHCT157NS is pin-compatible with the SN74LS157 and SN74HC157 in the 16-pin PDIP (N), SOIC (D), and SOP-NS packages. Pin assignments-including 1A/1B through 4A/4B, A/B, G, Y1–Y4, VCC, and GND-are identical across these devices, enabling drop-in replacement in existing layouts when upgrading from LS or HC logic to AHCT's improved speed and drive.