STMicroelectronics M74HC155B1R

Overview

M74HC155B1R from STMicroelectronics is a high-speed CMOS dual 2-to-4 line decoder/demultiplexer with independent strobe (1G, 2G) and data inputs (1C, 2C), common address inputs (A, B), and 8 active-low outputs (1Y0–1Y3, 2Y0–2Y3). It operates from 2V to 6V, delivers 13ns typical propagation delay at 6V, supports ±4mA symmetrical output drive, and features 4µA max quiescent current at 25°C - used in address decoding, data routing, and logic-level signal distribution in industrial control panels.

For engineers reviewing the M74HC155B1R datasheet, M74HC155B1R pinout, M74HC155B1R application, or M74HC155B1R equivalent, key selection criteria include dual-decoder enable control, inverted/non-inverted output polarity per section, wide VCC range compatibility, static discharge protection on all inputs, and DIP-16 package mechanical fit for legacy through-hole PCBs.

Technical Context

The M74HC155B1R implements two independent 2-to-4 decoders sharing binary address lines A and B, each with dedicated strobe (1G/2G) and data (1C/2C) inputs. Strobe assertion enables decoding; when enabled, 1C drives inverted outputs (1Y0–1Y3), while 2C drives non-inverted outputs (2Y0–2Y3).

It supports reconfiguration as a 3-to-8 demultiplexer by tying 1C and 2C to the same data source, yielding sequential outputs msb-first: 1Y3, 1Y2, 1Y1, 1Y0, 2Y3, 2Y2, 2Y1, 2Y0. All inputs include silicon-gate C2MOS ESD protection circuits rated for ±20mA diode current.

Key Specifications

Pinout & Package

Package: Plastic DIP-16 (0.300" width), 16-pin through-hole, JEDEC MS-001AC compliant, 20.0mm × 8.5mm body size, 2.54mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual decoder/demultiplexer applications.

Compared with SN74HC155N and CD74HC155E, M74HC155B1R offers the lowest ICC (4µA max) and fastest tPD (13ns typ), making it optimal for ultra-low-power and high-timing-margin applications - especially where DIP-16 mechanical compatibility is mandatory.

Availability

M74HC155B1R is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy microcontroller address decoding, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for M74HC155B1R 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, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog/mixed-signal products for industrial, automotive, and consumer markets.

The M74HC155B1R belongs to ST's high-speed HC logic family, engineered for pin-compatible upgrades to legacy 74LS devices while delivering CMOS power efficiency and enhanced noise immunity in industrial control and instrumentation systems.

FAQ

Can M74HC155B1R operate reliably at 2.0V supply?

Yes. The device is fully specified from 2.0V to 6.0V, with guaranteed VIH = 1.5V and VIL = 0.5V at VCC = 2.0V, and tPD ≤ 195ns (max) across −55°C to +125°C. Output drive remains functional at 2.0V, though IOL/IOH drops to ±2mA minimum - sufficient for driving HC/HCT inputs or high-impedance loads.

What is the function of the 1G and 2G pins?

1G and 2G are active-low strobe inputs that enable their respective decoder sections. When high, both 1Yx and 2Yx outputs enter high-impedance state regardless of address or data inputs. When low, decoding proceeds normally: 1C controls inverted outputs (1Y0–1Y3), and 2C controls non-inverted outputs (2Y0–2Y3).

Is M74HC155B1R compatible with 5V TTL logic inputs?

Yes. At VCC = 5V, VIH = 3.15V (min) and VIL = 1.35V (max), meeting TTL input thresholds. Outputs deliver VOH ≥ 4.4V and VOL ≤ 0.26V at 4mA load, satisfying TTL high/low voltage requirements - enabling direct interfacing with 74LS and 74F families without level shifters.

Does this part support 3-to-8 demultiplexing without external logic?

Yes. By connecting the same data signal to both 1C and 2C, and using A/B as the LSBs, the device produces eight sequential outputs: 1Y3, 1Y2, 1Y1, 1Y0, 2Y3, 2Y2, 2Y1, 2Y0. No external gates are needed - the internal architecture inherently supports this configuration per the datasheet truth table and logic diagram.