STMicroelectronics M74HC147RM13TR

Overview

M74HC147RM13TR from STMicroelectronics is a high-speed CMOS 10-to-4 line priority encoder with active-low inputs and outputs, operating from 2V to 6V supply, featuring 15ns typical propagation delay at 6V, 4µA max quiescent current at 25°C, and symmetrical 4mA output drive capability. It encodes nine decimal inputs (1–9) into a 4-bit BCD output, with implicit zero encoding when all inputs are high - used in keyboard scanning and interrupt prioritization circuits.

For engineers reviewing the M74HC147RM13TR datasheet, M74HC147RM13TR pinout, M74HC147RM13TR application, or M74HC147RM13TR equivalent, key selection criteria include active-low logic compatibility, priority encoding behavior, TSSOP-16 package constraints, BCD output mapping, and industrial temperature range (-55°C to +125°C) support.

Technical Context

The M74HC147 implements priority encoding logic where only the highest-order active-low input (e.g., input 9 > 8 > … > 1) determines the BCD output; lower-priority inputs are masked. Encoding is fully combinational with no internal clock or latch.

It uses silicon gate C2MOS technology for low power and high noise immunity (VNIH/VNIL ≥ 28% VCC), supports rail-to-rail input/output swing, and features integrated ESD protection on all pins per IEC 61000-4-2 Level 2.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.9 × 6.4 mm body, 0.65 mm pitch, 1.2 mm height, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar priority encoder applications.

Compared with SN74HC147N and 74AHC147PW, the M74HC147RM13TR offers optimal balance of industrial temperature range, TSSOP footprint, and 6V tolerance - making it preferred for automotive and dense industrial PCBs where reliability and density are jointly constrained.

Availability

M74HC147RM13TR is available at Aetrix Electronics and suitable for keyboard encoder interfaces, interrupt priority arbiters, legacy system bus decoders, and industrial control panels requiring stable component supply across extended temperature ranges.

Supply support for M74HC147RM13TR 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 M74HC147 belongs to ST's high-speed CMOS logic family, engineered for pin-compatible upgrades of legacy 74-series devices while delivering improved speed, power efficiency, and robustness in harsh environments.

FAQ

What is the logic polarity of inputs and outputs on the M74HC147RM13TR?

All nine decimal inputs (pins 1–5, 10–13) and four BCD outputs (pins 6, 7, 9, 14) are active-low. A logic low on input 9 produces output D=0, C=0, B=0, A=0 (i.e., BCD "9"), and all inputs high yields BCD "0". This matches standard 74-series priority encoder behavior.

Does the M74HC147RM13TR require external pull-up resistors on its inputs?

Yes - because inputs are active-low and lack internal pull-ups, external pull-up resistors (typically 4.7kΩ to VCC) are required to ensure defined HIGH states when keys or switches are open. Outputs may also need pull-ups if driving high-impedance loads, though they source/sink ±4mA.

Can the M74HC147RM13TR operate reliably at 2.0V supply voltage?

Yes - it is fully specified down to 2.0V: VIH = 1.5V min, VIL = 0.5V max, tPD = 125ns max (–40°C to +85°C), and ICC ≤ 40µA. However, output drive drops to ±20µA at 2V, so use only with high-impedance loads or add buffering for fanout.

Is pin 15 (NC) safe to connect to ground?

Yes - pin 15 is internally unconnected and may be tied to GND for mechanical reinforcement or EMI reduction, provided no solder bridge forms to adjacent pins. ST's mechanical drawings confirm no internal bond wire or die connection exists at this location.