Texas Instruments CD4056BNS

Overview

CD4056BNS 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 –55°C to +125°C and is housed in a 16-pin SOIC package (NSR suffix), commonly used in industrial panel meters and legacy instrumentation displays.

For engineers reviewing the CD4056BNS datasheet, CD4056BNS pinout, CD4056BNS application, or CD4056BNS equivalent, key selection considerations include its BCD latching capability, open-drain segment outputs with TTL/CMOS-compatible inputs, wide temperature range, and compatibility with common-cathode LED displays without external current-limiting resistors when driven into saturation.

Technical Context

The CD4056BNS integrates a 4-bit D-type latch, BCD-to-7-segment decoder logic, and seven open-drain N-channel MOSFET output drivers. Its latch enables synchronous data capture on the LE (Latch Enable) input, isolating display updates from input bus changes. The decoder implements standard 7-segment mapping (a–g) with blanking (BL) and lamp test (LT) control inputs.

All outputs are open-drain, requiring external pull-ups for LED anode connection in common-cathode configurations. Input thresholds are CMOS-compatible (V_IL ≤ 30% V_DD, V_IH ≥ 70% V_DD), and output sink current is specified at 1.5 mA minimum per segment at V_DD = 15 V and V_OL ≤ 0.5 V.

Key Specifications

Pinout & Package

CD4056BNS is supplied in a 16-pin small-outline integrated circuit (SOIC) package with NSR suffix, measuring 9.9 mm × 3.91 mm × 1.75 mm (JEDEC MS-012AC), moisture sensitivity level 1, and RoHS-compliant green finish (Pb-free, no Sb/Br).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD4511BE and 74HC4511PW, the CD4056BNS uniquely combines explicit latch control, open-drain outputs for common-cathode flexibility, and extended temperature range - making it the preferred choice for industrial and legacy-replacement designs demanding robustness and wiring compatibility.

Availability

CD4056BNS is available at Aetrix Electronics and suitable for industrial panel meters, avionics annunciators, and energy meter digit drivers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD4056BNS 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 headquartered in Dallas, Texas, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The CD4056BNS belongs to TI's legacy CMOS logic portfolio, originally developed for robust, low-power digital interface functions in harsh-environment instrumentation - emphasizing latch integrity, wide-V_DD tolerance, and direct LED drive capability.

FAQ

What is the primary function of the CD4056BNS?

The CD4056BNS is a CMOS BCD-to-7-segment latch/decoder/driver IC. Its primary function is to accept a 4-bit BCD input, latch it on the rising edge of LE, decode it into seven active-low segment signals (a–g), and drive common-cathode LED displays via open-drain outputs. The CD4056BNS integrates all three functions-latching, decoding, and driving-in a single 16-pin SOIC device, eliminating the need for discrete components in display subsystems.

Does the CD4056BNS support common-anode LED displays?

No, the CD4056BNS does not natively support common-anode LED displays. Its seven segment outputs (pins 9–15) are open-drain N-channel MOSFETs designed to sink current from LED cathodes to ground. To drive a common-anode display, external PNP transistors or level-shifting circuitry would be required - which defeats the purpose of the CD4056BNS's integrated open-drain architecture. The CD4056BNS is optimized for common-cathode configurations with externally pulled-up anodes.

What is the maximum sink current per segment output on the CD4056BNS?

The CD4056BNS guarantees a minimum sink current of 1.5 mA per segment output (pins a–g) when V_DD = 15 V and V_OL ≤ 0.5 V. This specification ensures reliable illumination of standard low-current indicator LEDs. At lower supply voltages (e.g., 5 V), sink capability decreases due to reduced MOSFET overdrive; actual current depends on external pull-up voltage and LED forward voltage. The CD4056BNS is not rated for continuous >2 mA per segment without thermal derating.

Can the CD4056BNS operate from a 3.3 V supply?

Yes, the CD4056BNS is fully specified to operate from 3 V to 18 V, including 3.3 V nominal supplies. However, at 3.3 V, its output sink current drops significantly (typically ~0.2 mA per segment), and LED brightness will be very low unless ultra-low-current LEDs or external amplification are used. For 3.3 V systems requiring full segment drive, the CD4056BNS remains functional but should be paired with high-efficiency LEDs or supplemental driver stages. The CD4056BNS maintains correct logic thresholds and latch behavior across the full range.

Is the CD4056BNS pin-compatible with the CD4511?

No, the CD4056BNS is not pin-compatible with the CD4511. While both are BCD-to-7-segment decoders with open-drain outputs, their pin assignments differ: CD4056BNS places BL (blanking) on pin 5 and LT (lamp test) on pin 6, whereas CD4511 places LT on pin 3 and BL on pin 4. Additionally, CD4056BNS uses LE (latch enable) on pin 7, while CD4511 uses a different latch mechanism tied to input transitions. Direct substitution requires PCB layout modification. The CD4056BNS pinout is fixed per its SOIC-NSR package definition and cannot be mapped to CD4511 without rewiring.