STMicroelectronics M74HC4543B1R

Overview

M74HC4543B1R from STMicroelectronics is a high-speed CMOS BCD-to-7-segment latch/decoder with integrated LCD driver in 16-pin DIP package. It features 14 ns typical propagation delay at 6 V, 4 µA max quiescent current at 25°C, and operates from 2 V to 6 V. Designed for direct LCD segment driving with phase-synchronized square-wave bias, it supports blanking via BI input and latching via LD control.

For engineers reviewing the M74HC4543B1R datasheet, M74HC4543B1R pinout, M74HC4543B1R application, or M74HC4543B1R equivalent, key selection factors include its LCD-specific AC drive capability, BCD input latching behavior, active-HIGH blanking and latch-disable logic, and symmetrical ±4 mA output drive strength under load.

Technical Context

The M74HC4543B1R integrates a BCD decoder, transparent latch, and 7-segment LCD driver in a single silicon-gate C2MOS IC. Its PH input synchronizes segment outputs to an external square-wave backplane signal, enabling AC-driven LCD biasing to prevent electrolytic degradation.

It implements active-HIGH blanking (BI) and latch-disable (LD) controls, with illegal BCD codes (10–15) and BI=H forcing all segment outputs low. Output polarity is inverted relative to PH when LD=H, supporting multiplexed LCD drive schemes with precise timing alignment.

Key Specifications

Pinout & Package

Package: 16-pin plastic DIP (0.300" wide), JEDEC MS-001, body dimensions 20.0 × 8.5 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar BCD-to-LCD decoder applications.

Compared with CD4543BE and 74HC4543N, M74HC4543B1R provides superior timing performance, integrated latching for interrupt-tolerant operation, and active lifecycle support-making it optimal for new industrial and automotive display designs requiring reliability and longevity.

Availability

M74HC4543B1R is available at Aetrix Electronics and suitable for industrial panel meters, automotive instrument clusters, portable medical devices, and point-of-sale terminals requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for M74HC4543B1R 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 broad analog and mixed-signal portfolio coverage.

M74HC4543B1R belongs to ST's high-speed HC logic family, designed specifically for low-power, high-reliability digital display interfaces in harsh environments where latch stability and LCD drive integrity are critical.

FAQ

Can M74HC4543B1R drive LED displays directly?

No. The M74HC4543B1R is optimized for AC-coupled LCD segments and lacks sufficient DC sink/source current for LEDs. Driving LEDs requires external transistor arrays or dedicated LED drivers like the TLC5916, as stated in the datasheet's "other types of readouts" note.

What is the required frequency and waveform for the PH input?

The PH input must be driven by a clean, symmetrical square wave matching the LCD backplane's operating frequency (typically 30–60 Hz for static LCDs, up to 100 kHz for multiplexed). Duty cycle must be 50 ±5%, and amplitude must swing rail-to-rail between GND and VCC.

How does the latch function interact with illegal BCD codes (10–15)?

When LD = L, illegal BCD codes (10–15) force all segment outputs low regardless of PH state. When LD = H, the latch holds the last valid code (0–9); illegal inputs do not overwrite the latch but still blank the display until a valid code is applied and latched.

Is decoupling required on VCC, and what value is recommended?

Yes. A 100 nF ceramic capacitor placed within 10 mm of pin 16 (VCC) and pin 8 (GND) is mandatory to suppress switching noise and ensure stable segment output levels, especially during rapid BCD changes or PH transitions, per ST's layout guidelines.