STMicroelectronics M74HC237B1R

Overview

M74HC237B1R from STMicroelectronics is a high-speed CMOS 3-to-8 line decoder with latch, operating from 2V to 6V supply, featuring tPD = 16ns (typ. at VCC = 6V), ICC ≤ 4µA (max. at TA = 25°C), and symmetrical output drive (|IOH| = IOL ≥ 4mA). It implements glitch-free address decoding in bus-oriented systems where stored-address stability is required, such as memory-mapped peripheral selection in industrial microcontroller interfaces.

For engineers reviewing the M74HC237B1R datasheet, M74HC237B1R pinout, M74HC237B1R application, or M74HC237B1R equivalent, key selection criteria include latch-enable timing (tW(L) = 6ns min. at VCC = 6V), dual active-high/active-low output enables (G1, G2), balanced propagation delays (tPLH ≅ tPHL), and DIP-16 package compatibility with legacy 74-series layouts.

Technical Context

The M74HC237B1R integrates a 3-bit address latch with independent G1 (active-high) and G2 (active-low) output enables, allowing outputs to be held low regardless of select inputs when enable conditions are unmet. Its C2MOS silicon gate process ensures low static current and high noise immunity (VNIH/VNIL ≥ 28% VCC).

Propagation delay paths are separately characterized for address inputs (A/B/C → Y), enable inputs (G1/G2 → Y), and latch-enable (GL → Y), with tPLH/tPHL matching within ±15% across temperature. All inputs include ESD protection diodes rated for ±20mA transient current.

Key Specifications

Pinout & Package

Package: Plastic DIP-16 (0.300" wide), JEDEC MS-001AC compliant, through-hole mountable with 2.54mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC237N and 74VHC237N, the M74HC237B1R offers the lowest ICC (4µA max.), full -55°C to +125°C operation, and proven robustness in high-noise industrial bus environments-making it optimal for long-lifecycle embedded control where power and reliability dominate speed requirements.

Availability

M74HC237B1R is available at Aetrix Electronics and suitable for industrial PLC backplanes, legacy microcontroller expansions, automated meter reading hubs, and test equipment signal routing requiring stable component supply over extended product lifecycles.

Supply support for M74HC237B1R 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, specializing in automotive, industrial, and power management ICs with vertical manufacturing capability.

The M74HC237B1R belongs to ST's high-reliability HC logic family, designed specifically for industrial control systems demanding extended temperature operation, low power, and immunity to electrical noise in harsh environments.

FAQ

What is the minimum GL pulse width required for reliable latching at 5V supply?

The minimum GL pulse width is 6ns at VCC = 6V and scales linearly with voltage; at 5V, the guaranteed minimum is 5ns per AC characterization data (tW(L) = 6ns @ 6V, 5ns @ 5V, 4ns @ 4.5V). This ensures compatibility with standard 5V microcontrollers toggling GPIO at ≤100MHz.

Can G1 and G2 be tied together to simplify enable control?

No - G1 is active-high and G2 is active-low; tying them directly creates a logic conflict that forces all outputs low. To simplify, use an inverter between G1 and G2 or replace with a single-enable decoder like M74HC138 if latching is not required.

Does the M74HC237B1R support hot insertion or live bus connection?

No - it lacks hot-swap protection circuitry. Input VI ratings (-0.5V to VCC+0.5V) and absence of Ioff specification mean applying VCC after signal inputs may cause latch-up. Always power VCC before applying input signals in modular backplane designs.

How does the latch behavior interact with continuous address changes while GL is high?

When GL is high, the internal latch holds the last captured A/B/C values; subsequent changes to A/B/C are ignored until GL goes low then high again. This ensures output stability even if address lines float or toggle during bus arbitration phases.