Texas Instruments CD4056BNSR

Overview

CD4056BNSR from Texas Instruments is a CMOS BCD-to-7-segment latch/decoder/driver IC designed for direct LED display interfacing. It features latched BCD input, active-low segment outputs capable of sinking up to 1.5 mA per segment, TTL-compatible input thresholds, and operates over a 3-V to 18-V supply range. It is used in panel meters, digital counters, and industrial status displays where low-power, high-voltage drive and latch functionality are required.

For engineers reviewing the CD4056BNSR datasheet, CD4056BNSR pinout, CD4056BNSR application, or CD4056BNSR equivalent, key selection considerations include its active-low open-drain segment outputs, built-in latch control (LE), BCD input validation, and compatibility with common-anode LED displays across wide supply voltage ranges.

Technical Context

The CD4056BNSR integrates a 4-bit latch, BCD-to-7-segment decoder, and seven active-low output drivers in a single 16-pin SO package. Its latch enables synchronous data capture before decoding, preventing transient display glitches during BCD updates.

Segment outputs are open-drain N-channel MOSFETs rated for 1.5 mA sink current at V_DD = 5 V and up to 3.5 mA at V_DD = 15 V, supporting direct drive of common-anode LEDs without external current-limiting resistors when used with appropriate anode biasing.

Key Specifications

Pinout & Package

CD4056BNSR is supplied in a 16-pin small-outline (SO) package with NS drawing, 5.3 mm body width, 1.2 mm max height, and 0.65 mm lead pitch compliant with JEDEC MO-153.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD4056BNSR, CD4511BE offers common-cathode compatibility but removes latch synchronization and lamp test, while MC14495P reduces integration at the cost of added board space and external logic-making CD4056BNSR optimal for noise-immune, multi-digit, common-anode systems requiring self-contained control.

Availability

CD4056BNSR is available at Aetrix Electronics and suitable for digital instrumentation, industrial HMI panels, and legacy equipment upgrades requiring stable component supply, long-term obsolescence mitigation, and RoHS-compliant small-outline packaging.

Supply support for CD4056BNSR 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 company founded in 1930, specializing in analog, embedded processing, and logic ICs for industrial, automotive, and consumer applications.

The CD4000-series CMOS logic family, including CD4056BNSR, was engineered for high-noise immunity, wide supply range operation, and direct LED drive capability in ruggedized instrumentation and control systems.

FAQ

What is the maximum sink current per segment output of the CD4056BNSR?

The CD4056BNSR segment outputs can sink up to 1.5 mA minimum at V_DD = 5 V and up to 3.5 mA minimum at V_DD = 15 V. These values are specified under DC conditions with V_OL ≤ 0.5 V. The actual current depends on external pull-up voltage and resistor value in common-anode configurations. Designers must verify thermal limits when driving multiple segments simultaneously in the CD4056BNSR.

Can the CD4056BNSR drive common-cathode LED displays directly?

No, the CD4056BNSR cannot drive common-cathode LED displays directly because its segment outputs are active-low open-drain. It is designed for common-anode configurations where the LED anodes connect to a positive rail and cathodes connect to CD4056BNSR outputs. Driving common-cathode displays would require external PNP transistors or level-shifting circuitry not supported by the CD4056BNSR architecture.

How does the Latch Enable (LE) pin function in the CD4056BNSR?

The LE pin on the CD4056BNSR is active-high and controls data transparency versus latching. When LE is high, BCD inputs pass through to the decoder in real time. When LE transitions low, the current BCD value is latched and held, ensuring stable segment outputs even if inputs change. This prevents display glitches during BCD bus updates and is essential for reliable operation in the CD4056BNSR.

What is the purpose of the Lamp Test (LT) pin on the CD4056BNSR?

The LT pin on the CD4056BNSR is an active-low input that forces all seven segment outputs (a–g) low simultaneously, illuminating the full digit pattern regardless of BCD input or latch state. This enables rapid hardware verification of LED segment continuity and PCB interconnect integrity without MCU intervention-critical for field service and manufacturing test of systems using the CD4056BNSR.

Is the CD4056BNSR compatible with 3.3 V logic systems?

The CD4056BNSR accepts 3.3 V as a valid V_DD supply and meets its input threshold specifications (V_IH ≥ 3.5 V at V_DD = 5 V), but at 3.3 V supply, V_IH is approximately 2.2 V - below typical 3.3 V logic high levels (~3.0 V). Therefore, direct interface with 3.3 V microcontrollers may cause unreliable recognition of high inputs unless buffered or level-shifted. This limitation applies specifically to the CD4056BNSR and must be addressed in system design.