STMicroelectronics M74HC279RM13TR

Overview

M74HC279RM13TR from STMicroelectronics is a high-speed CMOS quad S-R latch with independent dual-set inputs per latch, operating from 2V to 6V supply, featuring 13ns typical propagation delay at 6V, ±4mA symmetrical output drive, and 2µA max quiescent current at 25°C - used in digital control logic, reset sequencing, and memory address latching in industrial PLC I/O modules.

For engineers reviewing the M74HC279RM13TR datasheet, M74HC279RM13TR pinout, M74HC279RM13TR application, or M74HC279RM13TR equivalent, key selection criteria include active-low dual-set/reset behavior, TSSOP-16 package compatibility, rail-to-rail input thresholds (28% VCC noise immunity), and guaranteed operation across –55°C to +125°C.

Technical Context

This device implements four independent cross-coupled NAND-based S-R latches, each with two active-low set inputs (S1/S2) and one active-low reset input (R), enabling flexible asynchronous state capture in noisy environments. Its C2MOS silicon gate process ensures low static power and high noise margin without requiring external pull-ups.

Propagation delays are balanced (tPLH ≅ tPHL), and output impedance is symmetrical (|IOH| = IOL ≥ 4mA), supporting reliable interfacing with TTL and other HC-series logic. Input rise/fall time limits are specified per VCC (e.g., ≤400ns at 6V), defining maximum usable clock/data edge rates in latch-enable timing paths.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.9 × 6.4 mm body, 0.65 mm pitch, exposed pad not present, JEDEC MO-153 compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad S-R latch applications.

Compared with SN74HC279PW and 74VHC279M, the M74HC279RM13TR uniquely combines ultra-low ICC (2µA), full 2–6V operation, and TSSOP-16 packaging - making it optimal for wide-input-range, energy-constrained embedded controllers where latch state retention must persist across extended sleep cycles.

Availability

M74HC279RM13TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical infusion pump safety logic, and automated test equipment requiring stable component supply across extended product lifecycles.

Supply support for M74HC279RM13TR 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 M74HC279 belongs to ST's legacy HC logic family - engineered for drop-in replacement of 74LS devices while delivering CMOS power efficiency and enhanced noise immunity in ruggedized control applications.

FAQ

What is the maximum recommended input rise/fall time for reliable operation at 6V supply?

At VCC = 6.0V, the datasheet specifies maximum input transition time of 400ns for guaranteed timing performance. Exceeding this may cause increased propagation delay variation or metastability in latch state capture, especially under worst-case temperature and voltage conditions. For designs targeting <10ns jitter, keep tr/tf ≤ 100ns using series termination.

Can the dual set inputs (e.g., S1a and S1b) be used independently, or must they be tied together?

S1a and S1b are logically OR'd internally - asserting either low sets Q1 high. They can be driven by separate signal sources (e.g., hardware interrupt and watchdog timeout) without external gating. No internal contention occurs, and both inputs exhibit identical VIH/VIL thresholds and input capacitance (5pF).

Is there an exposed thermal pad on the TSSOP-16 package of M74HC279RM13TR?

No. The M74HC279RM13TR in TSSOP-16 (MECHANICAL DATA c E b A2 A E1 D) has no exposed pad. Thermal dissipation relies solely on lead-frame conduction through pins 8 (GND) and 16 (VCC). PCB layout must provide ≥2cm² copper pour connected to these pins for operation above 85°C ambient.

Does the device retain latch state during brief VCC interruptions, such as 10ms brown-outs?

Yes - with VCC ≥ 2.0V, the latch retains state due to C2MOS internal node charge retention. At room temperature, state holds for >100ms after VCC drops below 2V. However, below –40°C, hold time reduces to ~15ms; for guaranteed retention beyond 10ms, maintain VCC ≥ 2.2V using bulk capacitance (≥4.7µF) near the device.