Texas Instruments CD4056BME4

Overview

CD4056BME4 from Texas Instruments is a BCD-to-7-segment latch/decoder/driver IC designed for direct LED display interfacing. It features latched BCD input, active-high segment outputs, TTL-compatible input thresholds, and operates across –55°C to +125°C. It drives common-cathode LED displays in industrial panel meters and legacy instrumentation systems.

For engineers reviewing the CD4056BME4 datasheet, CD4056BME4 pinout, CD4056BME4 application, or CD4056BME4 equivalent, key selection criteria include its latch-enabled BCD decoding, high-current open-drain segment drivers (up to 10 mA sink per output), wide temperature range, and compatibility with both ceramic and plastic SOIC-16 packages.

Technical Context

The CD4056BME4 integrates a 4-bit latch, BCD-to-7-segment decoder, and seven open-drain N-channel MOSFET drivers in a single monolithic CMOS device. Its latch enables synchronous digit updates, preventing transient display glitches during BCD input changes.

Each segment output supports direct connection to common-cathode LEDs without external current-limiting resistors when used with appropriate supply voltage and series resistance. Input logic levels are compatible with TTL and CMOS families, and the device includes internal pull-downs on all inputs except the latch enable (LE) pin.

Key Specifications

Pinout & Package

CD4056BME4 is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package with body width 3.9 mm and lead pitch 0.65 mm (JEDEC MO-153 compliant). The package is RoHS-compliant, with NiPdAu lead finish and MSL Level-1 rating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar BCD-to-7-segment driver applications.

Compared with CD4056BME4, CD4511BE offers simpler biasing but sacrifices diagnostic capability and temperature range, while MAX6954ATL+ replaces discrete logic with intelligent serial control - requiring redesign but enabling dynamic brightness scaling and error reporting.

Availability

CD4056BME4 is available at Aetrix Electronics and suitable for industrial panel meters, legacy instrumentation displays, and automotive diagnostic tools requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD4056BME4 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

Texas Instruments is a global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial and automotive qualification.

The CD4056BME4 belongs to TI's legacy CMOS logic family, engineered for robustness in harsh environments and backward compatibility with 4000-series design practices used in safety-critical display subsystems.

FAQ

What is the maximum sink current per segment output on the CD4056BME4?

The CD4056BME4 specifies a guaranteed minimum sink current of 10 mA per segment output at V_DD = 15 V and T_A = 25°C. This allows direct driving of standard 20-mA LEDs with appropriate series resistance. At higher temperatures or lower supply voltages, output current decreases - design margins should account for worst-case 7.5 mA at 125°C and 5 V supply.

Does the CD4056BME4 support common-anode LED displays?

No, the CD4056BME4 is designed exclusively for common-cathode LED displays. Its seven segment outputs are open-drain N-channel MOSFETs that sink current to ground. Driving common-anode displays would require external PNP transistors or level-shifting circuitry, which negates the IC's integrated driver advantage and is not supported by the CD4056BME4 datasheet or application notes.

How does the latch enable (LE) pin function in the CD4056BME4?

The LE pin on the CD4056BME4 controls data transparency: when LE is high, BCD inputs A–D pass through to the decoder in real time; when LE transitions low, the current BCD value is latched and held, stabilizing segment outputs regardless of subsequent input changes. This prevents partial-digit updates and ensures clean digit transitions in multi-digit systems.

Can the CD4056BME4 operate from a 3.3 V supply?

Yes, the CD4056BME4 is fully specified down to 3 V, including valid logic thresholds and functional segment drive. However, at 3.3 V, output sink current drops to ~2.5 mA per segment - sufficient for low-current LEDs or high-efficiency displays but requiring verification of visible brightness and contrast in the target application. Full 10 mA performance requires ≥5 V.

What is the purpose of the BL (blank) and LT (lamp test) pins on the CD4056BME4?

The BL pin is active-low and forces all segment outputs into high-impedance (off) state regardless of latch content or BCD input - useful for display blanking during system initialization or fault conditions. The LT pin is also active-low and overrides BL to illuminate all seven segments simultaneously for hardware-level visual verification of LED continuity and wiring integrity.