STMicroelectronics HCF4056BEY

Overview

HCF4056BEY from STMicroelectronics is a BCD-to-7-segment decoder/driver IC with strobed latch and on-chip level-shifting capability, designed specifically for driving LCD and LED displays. It supports VDD up to 20V, provides 18V (VDD–VEE) AC drive across LCD segments yielding effective 36V_p-p, delivers ±100nA max input leakage at 18V, and decodes all 16 BCD inputs including digits 0–9 and characters L, H, P, A, dash, and blank.

For engineers reviewing the HCF4056BEY datasheet, HCF4056BEY pinout, HCF4056BEY application, or HCF4056BEY equivalent, key selection considerations include its dual-rail output swing (VDD to VEE), DF-controlled AC/DC segment drive mode, strobe-synchronized BCD latching, and compatibility with legacy CMOS display systems requiring ultra-low quiescent current and no external capacitor for LCD bias.

Technical Context

The HCF4056BEY integrates full BCD decoding (0–9, L, H, P, A, –, blank) with a strobed input latch that freezes BCD data on the rising edge of STROBE. Its internal level-shifting architecture allows independent setting of input swing (VDD to VSS) and output swing (VDD to VEE), enabling operation with negative VEE down to –5V while maintaining TTL- or CMOS-compatible input thresholds.

Display Frequency (DF) input controls output polarity and waveform: low → high-active segments; high → low-active segments; square wave → 180° out-of-phase AC drive for selected segments. DF frequency range is optimized for LCDs (30–200Hz), and the device requires pairing with HCF4054B to generate common DF signals in multi-digit systems.

Key Specifications

Pinout & Package

Package: 16-pin Plastic DIP (0.300" width), 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-7-segment decoder/driver applications.

Compared with CD4511BE and MC14495P, HCF4056BEY uniquely combines strobed latching, programmable AC/DC segment drive via DF, and independent input/output rail control - making it the sole option among these three for reliable, capacitor-free LCD driving in harsh or battery-constrained environments.

Availability

HCF4056BEY is available at Aetrix Electronics and suitable for automotive instrument clusters, industrial panel meters, portable medical devices, and legacy test equipment requiring stable component supply and long-term obsolescence mitigation.

Supply support for HCF4056BEY 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, digital, and mixed-signal portfolios.

HCF4056BEY belongs to the HCF4000B series of radiation-hardened, high-voltage CMOS logic ICs engineered for reliability-critical display interfaces in automotive, aerospace, and industrial instrumentation.

FAQ

Can HCF4056BEY drive LED displays directly?

Yes - it can drive low-current LED segments in DC mode when DISPLAY-FREQUENCY (DF) is held high or low. Output sink/source capability is ±0.95 mA at VDD = 15 V, sufficient for standard 7-segment LEDs with series resistors. However, for high-brightness or multiplexed LED arrays, external drivers are recommended due to thermal limits (100 mW per output transistor).

What is the purpose of the VSS and VEE pins being separate?

VSS serves as the reference ground for BCD inputs and logic core, while VEE sets the negative output rail for segment drivers. Separating them enables level-shifting: e.g., VDD = 5 V, VSS = 0 V (TTL-compatible inputs), VEE = –5 V (10 V output swing for LCD). This avoids signal integrity issues when interfacing low-voltage controllers with high-contrast LCDs.

Is HCF4056BEY still in active production?

No - STMicroelectronics has marked HCF4056BEY as obsolete (as noted in the datasheet header). However, Aetrix Electronics maintains verified, traceable inventory of original ST-branded HCF4056BEY in DIP-16 packaging with full lot traceability and extended lifecycle support for legacy design refreshes.

How does the strobe function improve display stability?

The STROBE pin latches BCD inputs on its rising edge, freezing the displayed digit regardless of subsequent bus activity. This prevents partial or ghosted segments during rapid BCD updates - critical in multiplexed displays where microcontroller writes may overlap digit scanning cycles, ensuring crisp, jitter-free visual output.