STMicroelectronics M74HC4851RM13TR

Overview

M74HC4851RM13TR from STMicroelectronics is a single 8-channel analog multiplexer/demultiplexer with injection current protection, designed for high-reliability signal routing in mixed-voltage environments. It operates from 2 V to 6 V, delivers 150 Ω typical ON resistance at 6 V, achieves 8.6 ns propagation delay at 4.5 V, and supports automotive-grade temperature range (−55 °C to +125 °C) in SO-16 package - used in engine control unit sensor signal conditioning.

For engineers reviewing the M74HC4851RM13TR datasheet, M74HC4851RM13TR pinout, M74HC4851RM13TR application, or M74HC4851RM13TR equivalent, key selection criteria include injection current immunity (≤1 mV output shift under 1 mA injection), latch-up robustness (>500 mA), and compatibility with legacy 4051/4851 logic families in analog front-end switching.

Technical Context

The M74HC4851RM13TR implements silicon gate C2MOS technology with dedicated injection current control circuitry that isolates enabled channels from voltage excursions on disabled inputs - enabling signals up to VCC + 0.5 V or down to GND without cross-talk. Its three-bit binary select (A/B/C) and active-low INH input provide deterministic channel routing with no glitch during transitions.

It features dual-domain operation: digital control pins (VIH = 3.15 V min at VCC = 4.5 V) interface cleanly with HC/TTL logic, while analog I/O pins tolerate ±25 mA diode current and support ≤1.2 V static voltage differential across the switch - critical for fault-tolerant sensor multiplexing in harsh environments.

Key Specifications

Pinout & Package

Package: SO-16 (Small Outline, 16-pin), body size 9.9 mm × 6.0 mm × 1.75 mm, ECOPACK® compliant, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar analog multiplexer applications.

Compared with CD74HC4051M96 and TS5A23157DCUR, the M74HC4851RM13TR uniquely combines automotive temperature range, documented injection current immunity, and >500 mA latch-up rating - making it the only choice for safety-critical analog routing in harsh environments.

Availability

M74HC4851RM13TR is available at Aetrix Electronics and suitable for automotive engine control units, industrial sensor hubs, and medical patient monitors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for M74HC4851RM13TR 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 management ICs, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.

The M74HC4851 belongs to ST's high-reliability HC logic family, engineered specifically for analog signal routing in electrically noisy, thermally demanding applications where fault tolerance and long-term stability are mandatory.

FAQ

What is the maximum allowable voltage across the analog switch when enabled?

The M74HC4851RM13TR specifies a maximum static or dynamic voltage across the switch of 0 to 1.2 V when enabled. Exceeding 1.2 V may cause excessive VCC current draw due to conduction through internal parasitic paths, though device reliability remains unaffected unless absolute maximum ratings (e.g., VI/O = −0.5 V to VCC + 0.5 V) are violated.

Can the M74HC4851RM13TR operate with a 3.3 V supply while interfacing with 5 V logic controllers?

Yes - its control inputs (A/B/C/INH) accept VIH ≥ 2.1 V at VCC = 3.3 V, fully compatible with 3.3 V logic. For 5 V controllers, a simple resistive divider or HC-series buffer is recommended to limit VIN to ≤ VCC + 0.5 V, as absolute max VI/O is VCC + 0.5 V - not 5 V directly.

Is the NC pin (Pin 7) required to be grounded or left floating?

Pin 7 is internally unconnected and must remain unconnected - neither grounded nor tied to any voltage. ST's datasheet explicitly states "Not connected", and connecting it risks unintended coupling or mechanical stress on the bond wire. No thermal or electrical benefit is gained from routing it to ground.

How does injection current protection function without external components?

The M74HC4851RM13TR integrates on-die current-limiting structures and isolation circuitry that shunt injected current away from the enabled channel's signal path. When up to 1 mA enters a disabled channel, internal clamping limits voltage perturbation at the COM node to ≤1 mV - verified per test circuit 2 in Doc ID 8640 Rev 7, eliminating need for external diode-resistor networks.