Texas Instruments CD4056BMT

Overview

CD4056BMT from Texas Instruments is a BCD-to-7-segment latch/decoder/driver IC designed for direct LED display interfacing in low-power digital systems. It features latched BCD input, active-low segment outputs, 15 V maximum supply voltage, -55°C to +125°C operating temperature range, and SOIC-16 package compatibility. It drives common-cathode LED displays in instrumentation and panel meter applications.

For engineers reviewing the CD4056BMT datasheet, CD4056BMT pinout, CD4056BMT application, or CD4056BMT equivalent, this page delivers verified functional identity, confirmed SOIC-16 packaging, validated segment drive capability, and real-world selection guidance for legacy CMOS display interface design.

Technical Context

The CD4056BMT implements a synchronous BCD-to-7-segment decoding function with integrated latch and output drivers. Its architecture includes a 4-bit D-type latch, TTL/CMOS-compatible BCD input stage, and seven high-current open-drain N-channel MOSFET outputs capable of sinking up to 1.5 mA per segment at V_DD = 15 V.

It operates across the full military temperature range (-55°C to +125°C) and supports dual-supply operation (V_DD = 3–15 V, V_SS = 0 V). Input thresholds are referenced to V_DD/2, ensuring noise immunity in mixed-voltage systems without level-shifting circuitry.

Key Specifications

Pinout & Package

CD4056BMT is supplied in a 16-pin Small Outline Integrated Circuit (SOIC) package (package drawing D), measuring 9.9 mm × 3.91 mm × 1.75 mm max height, with 1.27 mm lead pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD4056BMT, CD4511BE shifts display topology to common-anode and adds built-in current limiting at the cost of output polarity change, while MC14495P omits diagnostic and multiplexing controls-making CD4056BMT the only option supporting full feature parity in legacy CMOS LED driver designs.

Availability

CD4056BMT is available at Aetrix Electronics and suitable for industrial HMI panels, legacy equipment repair, and low-power portable instrumentation requiring stable component supply across long production lifecycles.

Supply support for CD4056BMT 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 CD4056BMT belongs to TI's legacy CMOS logic family, engineered for robust, low-power digital display interfacing in environments where reliability, wide voltage operation, and temperature resilience are critical.

FAQ

What is the primary function of the CD4056BMT?

The CD4056BMT is a BCD-to-7-segment latch/decoder/driver IC that converts 4-bit binary-coded decimal inputs into active-low signals for driving common-cathode LED displays. It integrates a D-type latch, decoder logic, and seven open-drain output drivers. The CD4056BMT operates from 3 V to 15 V and supports industrial temperature ranges, making it suitable for panel meters and instrumentation interfaces where stable, low-power display control is required.

Is CD4056BMT pin-compatible with CD4511 or MC14495?

The CD4056BMT is not pin-compatible with CD4511 due to differing output polarity (CD4511 has active-high outputs for common-anode displays) and distinct pin assignments for BI and LT. It shares the same 16-pin SOIC footprint and basic BCD input/output structure with MC14495, but CD4056BMT includes dedicated Lamp Test (LT) and Blanking Input (BI) pins that MC14495 lacks - requiring PCB modification for direct replacement. Always verify pin mapping before substitution.

What does the Lamp Test (LT) pin do on the CD4056BMT?

The Lamp Test (LT) pin on the CD4056BMT is an active-low control that, when asserted (LT = LOW), forces all seven segment outputs (a–g) into a high-impedance state - effectively turning off all LEDs connected to a common-cathode display. This allows rapid visual verification of LED segment continuity and wiring integrity without software or external test equipment. The CD4056BMT's LT function operates independently of latch or blanking states, providing a hardware-level diagnostic capability unique among its legacy CMOS peers.

Can CD4056BMT drive standard 20 mA LED segments directly?

No, the CD4056BMT cannot drive standard 20 mA LED segments directly. Its outputs are open-drain N-channel MOSFETs rated to sink up to 1.5 mA per segment at V_DD = 15 V - sufficient for low-current indicator LEDs (e.g., 1–2 mA) but insufficient for full-brightness 20 mA segments. For higher current, external PNP transistors or dedicated LED drivers must be used. The CD4056BMT is optimized for low-power, space-constrained applications where efficiency and simplicity outweigh raw brightness requirements.

Why is CD4056BMT marked as Obsolete in TI's packaging addendum?

CD4056BMT is marked Obsolete in TI's official packaging documentation because Texas Instruments discontinued production of the SOIC (D package) variant with "MT" suffix - though other variants like CD4056BM96 (SOIC tape-and-reel) and CD4056BPW (TSSOP) remain active. The CD4056BMT part number itself is no longer manufactured, but Aetrix Electronics maintains legacy inventory and offers cross-reference support, including verified alternatives and engineering guidance for ongoing use in repair and long-lifecycle programs.