STMicroelectronics M74HC4078B1R

Overview

M74HC4078B1R from STMicroelectronics is a high-speed CMOS 8-input NOR/OR gate in a 14-pin plastic DIP package, operating from 2V to 6V supply, with 10ns typical propagation delay at 6V, ±4mA symmetrical output drive, and 1µA max quiescent current at 25°C - used in digital logic arbitration, enable gating, and reset signal combining in industrial control panels.

For engineers reviewing the M74HC4078B1R datasheet, M74HC4078B1R pinout, M74HC4078B1R application, or M74HC4078B1R equivalent, this device delivers verified NOR/OR logic function with rail-to-rail input compatibility, balanced tPLH/tPHL delays, and IEC-standard logic symbols for direct integration into legacy 74-series-compatible designs.

Technical Context

The M74HC4078B1R implements dual-function logic: all eight inputs feed a single NOR gate whose output is Y, while the same inputs also drive an OR gate with complementary output X (Y = NOT(A+B+...+H), X = A+B+...+H). It uses silicon gate C2MOS technology for low static power and high noise immunity (VNIH/VNIL ≥ 28% VCC).

Input protection circuits guard against ESD and transient overvoltage. Propagation delays are tightly matched (tPLH ≅ tPHL), and output impedance is symmetrical (|IOH| = IOL ≥ 4mA) across the full 2–6V VCC range and –55°C to +125°C operating temperature.

Key Specifications

Pinout & Package

Package: Plastic DIP-14 (Dual In-line Package), 0.3" wide, through-hole mount, JEDEC MS-001 compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-input NOR/OR logic applications.

Compared with SN74HC4078N and CD74HC4078E, the M74HC4078B1R offers broader temperature qualification (–55°C to +125°C), making it the only choice for aerospace, under-hood, or high-reliability industrial deployments requiring full military-grade thermal margin.

Availability

M74HC4078B1R is available at Aetrix Electronics and suitable for industrial PLC input conditioning, legacy system bus arbitration, and power-on reset synchronization requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for M74HC4078B1R 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 analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The M74HC4078B1R belongs to ST's high-speed HC logic family, engineered for drop-in replacement of legacy 74-series devices while delivering improved speed, power efficiency, and temperature resilience.

FAQ

What logic functions does the M74HC4078B1R implement?

The M74HC4078B1R integrates two complementary 8-input logic gates: a NOR gate outputting at pin 1 (Y) and an OR gate outputting at pin 13 (X). Both share identical inputs (pins 2–5 and 9–12), enabling simultaneous generation of active-low and active-high aggregate signals without external inversion.

Is the M74HC4078B1R pin-compatible with older 74LS4078 devices?

Yes - the M74HC4078B1R uses the same DIP-14 footprint and pin assignments as the 74LS4078, including identical input (2–5, 9–12), output (1, 13), VCC (14), and GND (7) locations. However, HC logic thresholds differ: VIH/VIL are ratio-based (28% VCC), not fixed TTL levels.

Can the M74HC4078B1R drive a 50pF capacitive load at 10MHz?

Yes - with tPLH/tPHL ≤ 25ns (max) at VCC = 6V and CL = 50pF, the device supports clean 10MHz square-wave propagation. Output drive strength (≥4mA) ensures adequate slew rate; measured CPD = 37pF confirms low dynamic power draw at that frequency.

Does the M74HC4078B1R require external pull-up or pull-down resistors on unused inputs?

No - all eight inputs include integrated protection diodes and have defined logic thresholds. Unused inputs must be tied to VCC or GND to prevent floating states and unintended switching; no external resistors are needed for DC biasing, though 10kΩ pull-ups/downs are acceptable for mechanical switch interfaces.