STMicroelectronics 74AC157TTR

Overview

74AC157TTR from STMicroelectronics is a quad 2-channel non-inverting CMOS multiplexer with common SELECT and STROBE inputs, operating across 2V–6V supply, delivering 4ns typical propagation delay at 5V, ±24mA symmetrical output drive, and 2kV ESD immunity. It routes A/B data sources to four independent Y outputs in industrial control logic, digital test equipment, and address/data bus selection.

For engineers reviewing the 74AC157TTR datasheet, 74AC157TTR pinout, 74AC157TTR application, or 74AC157TTR equivalent, key selection criteria include guaranteed 50Ω transmission line driving, latch-up immunity, balanced tPLH/tPHL delays, and TSSOP-16 compatibility with legacy 74-series footprint requirements.

Technical Context

The device implements four independent 2:1 multiplexers sharing one active-low STROBE and one SELECT input; when STROBE = HIGH, all Y outputs are forced LOW regardless of SELECT state. Selection is non-inverting: SELECT = LOW routes A-inputs to Y-outputs; SELECT = HIGH routes B-inputs.

Designed using sub-micron C2MOS technology, it features symmetrical output impedance (|IOH| = |IOL| ≥ 24mA), high noise immunity (VNIH/VNIL ≥ 28% VCC), and operates over –55°C to +125°C with quiescent ICC ≤ 4µA at 25°C.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.9mm × 6.4mm body, 0.65mm pitch, 1.1mm height, lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AC157DR and 74LVC157PW, the 74AC157TTR uniquely combines wide supply range, TSSOP-16 compactness, and guaranteed 50Ω line driving-making it optimal for space-constrained, mixed-voltage industrial controllers requiring field-replaceable logic.

Availability

74AC157TTR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, automotive body control modules, and digital test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74AC157TTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing microcontrollers, power management ICs, sensors, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The 74AC logic family targets high-speed, low-power, and robust industrial interface applications-emphasizing noise immunity, wide voltage operation, and enhanced reliability over standard 74-series parts.

FAQ

Is the 74AC157TTR pin-compatible with standard 74LS157 devices?

Yes, it is pin- and function-compatible with 74LS157, 74HC157, and 74HCT157 in TSSOP-16 packaging. All share identical pin numbering, SELECT/STROBE logic behavior, and quad 2:1 multiplexer functionality-enabling drop-in replacement with improved speed, drive strength, and supply range.

What is the maximum recommended load capacitance for reliable 4ns propagation delay?

The 4ns typical tPD is specified at CL = 50pF and RL = 500Ω per AC test conditions. For loads exceeding 50pF, propagation delay increases linearly; operation remains functional up to 100pF, but tPD degrades to ~6ns. Maintain trace lengths <10cm and avoid stubs to preserve timing integrity.

Does the STROBE input override SELECT when asserted?

Yes-when STROBE is HIGH, all four Y outputs are forced LOW regardless of SELECT state or A/B input values. This provides hardware-level channel blanking for synchronization, fault isolation, or power sequencing without software intervention.

Can the 74AC157TTR operate reliably at 2.5V supply in battery-powered applications?

Yes-it is fully specified down to 2V, including VIH/VIL thresholds, output drive, and propagation delay. At 2.5V, tPD increases to ~9ns (max), IOH/IOL drops to ≥12mA, and noise margin remains ≥28% of VCC-making it suitable for low-power portable instrumentation with regulated 2.5V rails.