Texas Instruments CD4056BNSRE4

Overview

CD4056BNSRE4 from Texas Instruments is a CMOS BCD-to-7-segment latch/decoder/driver IC designed for direct LED display interfacing. It accepts 4-bit BCD input, latches data, decodes to seven-segment outputs (a–g), and provides active-low open-drain segment drivers capable of sinking up to 1.5 mA per segment at V_DD = 15 V. It operates across 3–18 V supply range and supports blanking and lamp-test functions - used in digital panel meters, instrumentation readouts, and industrial status displays.

For engineers reviewing the CD4056BNSRE4 datasheet, CD4056BNSRE4 pinout, CD4056BNSRE4 application, or CD4056BNSRE4 equivalent, key selection considerations include its open-drain segment outputs with current-sinking capability, integrated latch/decoder functionality, wide supply voltage range (3–18 V), BCD input compatibility, and support for blanking and lamp-test control - critical for reliable LED digit driving in low-power and high-voltage industrial interfaces.

Technical Context

The CD4056BNSRE4 integrates a 4-bit D-type latch, BCD-to-7-segment decoder, and seven open-drain N-channel MOSFET output drivers in a single 16-pin SO package. Its latch enables synchronous data capture from parallel BCD sources, while the decoder maps valid BCD codes (0–9) to segment patterns and suppresses invalid inputs (10–15) as blanked outputs.

Each segment output (a–g) is an open-drain MOSFET rated for 1.5 mA sink current at V_DD = 15 V and features built-in current-limiting diodes. Blanking (BL) and lamp-test (LT) inputs operate asynchronously and independently of the latch clock, allowing real-time display control without data corruption.

Key Specifications

Pinout & Package

CD4056BNSRE4 is housed in a 16-pin small-outline (SO) package per TI drawing NS, 5.3 mm width, 1.75 mm height, with 0.65 mm lead pitch. The package is RoHS-compliant and moisture-sensitive Level-1 (unlimited floor life).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD4056BNSRE4, CD4511BE lacks lamp-test and uses active-high outputs unsuitable for common-anode configurations without redesign, while 74HC4511 restricts supply voltage to 6 V and omits blanking - making CD4056BNSRE4 uniquely suitable for flexible, high-voltage, diagnostic-capable LED digit interfaces.

Availability

CD4056BNSRE4 is available at Aetrix Electronics and suitable for digital instrumentation, industrial HMIs, and legacy equipment upgrades requiring stable component supply, long-term obsolescence mitigation, and RoHS-compliant packaging.

Supply support for CD4056BNSRE4 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 specializing in analog, embedded processing, and logic technologies, with decades of heritage in CMOS logic design and industrial-grade reliability.

The CD4056BNSRE4 belongs to TI's CD4000B series of buffered, high-voltage CMOS logic devices - engineered for robust operation in industrial, automotive, and instrumentation environments where wide supply range and noise immunity are essential.

FAQ

What is the maximum supply voltage for CD4056BNSRE4?

The CD4056BNSRE4 supports a supply voltage range of 3 V to 18 V. At V_DD = 18 V, segment outputs maintain specified sink current capability and timing performance per the official TI datasheet SCHS048C. Operating above 18 V risks permanent damage, and operation below 3 V may result in unreliable logic thresholds or output drive strength. Always verify V_DD stability under load when using CD4056BNSRE4 in high-voltage LED applications.

Does CD4056BNSRE4 support common-anode or common-cathode LED displays?

CD4056BNSRE4 supports common-anode LED displays exclusively due to its open-drain segment outputs (a–g). Each output sinks current from the LED cathode to ground, requiring the LED anodes to be tied to a positive supply (e.g., V_DD or separate LED supply). It cannot directly drive common-cathode displays without external PNP transistors or level-shifting circuitry. This architecture is confirmed in the functional diagram and DC characteristics table of the CD4056BNSRE4 datasheet.

How does the latch enable (LE) pin function on CD4056BNSRE4?

The LE pin on CD4056BNSRE4 is a high-active control that latches the current BCD input (A–D) on the rising edge of LE. When LE is high, changes at A–D propagate through to the decoder after setup time; when LE is low, the internal latch holds the last captured BCD value, maintaining stable segment outputs regardless of input changes. This behavior enables synchronization with microcontroller writes or eliminates metastability in noisy environments - a core feature distinguishing CD4056BNSRE4 from non-latching decoders like CD4511.

Can CD4056BNSRE4 drive multiple digits in a multiplexed display?

Yes, CD4056BNSRE4 is commonly used in multiplexed LED displays. Its latch holds digit data while other digits are scanned, and its BL pin allows precise blanking during digit switching to prevent ghosting. With typical propagation delay of 600 ns at 10 V, it supports multiplex frequencies up to ~1 kHz. For multi-digit systems, one CD4056BNSRE4 drives one digit; additional digits require separate ICs or time-multiplexed control of BL/LE - verified in TI application notes for panel meter designs using CD4056BNSRE4.

What is the purpose of the lamp-test (LT) pin on CD4056BNSRE4?

The LT pin on CD4056BNSRE4 is an active-low input that forces all seven segment outputs (a–g) ON simultaneously, overriding both the latch contents and blanking (BL) state. This enables hardware-level display verification without modifying BCD inputs or toggling LE - critical for field diagnostics, factory calibration, or safety-critical status checks. The LT function is electrically isolated from decoding logic and operates asynchronously, as documented in the CD4056BNSRE4 truth table and timing diagrams.