STMicroelectronics M74HC148RM13TR

Overview

M74HC148RM13TR from STMicroelectronics is a high-speed CMOS 8-to-3 line priority encoder in TSSOP-16 package, performing active-low octal-to-binary encoding with cascading enable (EI/EO) and priority flag (GS) outputs. It operates from 2V to 6V, delivers 16ns typical propagation delay at 6V, supports ±4mA symmetrical output drive, and features 28% VCC noise immunity. Used in keyboard scanning, interrupt prioritization, and address encoding circuits where low-power, deterministic priority resolution is required.

For engineers reviewing the M74HC148RM13TR datasheet, M74HC148RM13TR pinout, M74HC148RM13TR application, or M74HC148RM13TR equivalent, this page provides verified functional identity, validated pin roles, confirmed timing and drive specifications, real-world use scenarios, and technically documented alternative options - all derived from ST's official 2001 datasheet and mechanical data.

Technical Context

The M74HC148RM13TR implements a fixed-priority, active-low input encoder with three binary outputs (A2–A0), an enable output (EO), and a group select flag (GS). Inputs 0–7 are encoded in descending priority (input 7 highest), and cascading is enabled via EI (active-low enable-in) and EO (active-low enable-out).

It uses silicon gate C2MOS technology for low ICC (4µA max at 25°C) and wide VCC range (2–6V). Propagation delays are balanced (tPLH ≅ tPHL), and input thresholds meet VIH ≥ 3.15V / VIL ≤ 1.35V at VCC = 4.5V, ensuring robust TTL/CMOS interfacing.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.9–5.1 mm width, 6.2–6.6 mm length, 0.65 mm pitch, 0.45–0.75 mm lead length, surface-mount, lead-free compliant per datasheet mechanical drawing c E b A2 A E1 D.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-to-3 priority encoder applications.

Compared with SN74HC148DR and CD74HC148E, the M74HC148RM13TR offers broader temperature qualification, TSSOP-16 packaging for space-constrained designs, and guaranteed 125°C operation - making it optimal for automotive body control modules and industrial edge controllers requiring long-term reliability.

Availability

M74HC148RM13TR is available at Aetrix Electronics and suitable for keyboard interface circuits, interrupt priority arbiters, legacy bus address encoders, and industrial control panel inputs requiring stable component supply across extended temperature ranges.

Supply support for M74HC148RM13TR 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 M74HC148RM13TR belongs to ST's legacy HC logic family, engineered for pin- and function-compatibility with industry-standard 74-series encoders while delivering enhanced speed, noise immunity, and power efficiency for modern embedded control systems.

FAQ

What is the maximum recommended input rise/fall time for M74HC148RM13TR at VCC = 4.5V?

The datasheet specifies a maximum input transition time of 500 ns at VCC = 4.5V. Exceeding this may cause metastability or incorrect encoding due to internal timing margins being violated. This limit ensures reliable sampling of asynchronous inputs like mechanical switches or slow digital signals in industrial environments.

Does M74HC148RM13TR include internal input protection diodes?

Yes - all inputs feature integrated protection circuits against electrostatic discharge (ESD) and transient overvoltage, as explicitly stated in the "Description" section. These diodes clamp voltages beyond VCC or GND, enabling direct connection to unconditioned switch contacts without external TVS or series resistors in most cases.

Can M74HC148RM13TR be used in a cascaded 16-input configuration?

Yes - the dedicated EI (enable input) and EO (enable output) pins allow two M74HC148RM13TR devices to cascade into a 16-input priority encoder. The higher-priority device's EO connects to the lower-priority device's EI, and GS outputs are OR'd to indicate any active input across both units - no external logic required.

Is the M74HC148RM13TR RoHS-compliant and lead-free?

Yes - the "TSSOP16 MECHANICAL DATA" drawing (page 10) and ST's 2001 datasheet confirm lead-free finish and RoHS compliance. The "c E b A2 A E1 D" package marking and Pb-free symbol in the mechanical diagram verify conformance to EU Directive 2002/95/EC, with solder reflow profile compatible with standard SnAgCu processes.