Texas Instruments CD4543BMT

Overview

CD4543BMT 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 features phase control for common-anode displays, with supply voltage range of 3 V to 18 V and operating temperature from –55 °C to +125 °C.

For engineers reviewing the CD4543BMT datasheet, CD4543BMT pinout, CD4543BMT application, or CD4543BMT equivalent, this page provides verified functional identity, confirmed SOIC-16 package mapping, latch+decode timing behavior, phase-select logic for anode/cathode compatibility, and validated alternative options for legacy display interface designs.

Technical Context

The CD4543BMT implements a synchronous latch followed by active-low 7-segment decoding logic optimized for driving common-anode LEDs. Its PH (phase) input selects output polarity: high enables active-low segment drivers (for common-anode), low inverts outputs for common-cathode use.

It includes LE (latch enable) and BI (blanking input) controls - LE transfers BCD data on high-to-low transition, while BI forces all segment outputs high when asserted. No internal current limiting is provided; external resistors are required per segment.

Key Specifications

Pinout & Package

CD4543BMT is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package, designated as package drawing D, with 1.27 mm lead pitch and body dimensions of 10.4 mm × 5.4 mm × 1.75 mm max height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD4543BMT, CD4543BM96 offers identical performance with enhanced manufacturability and lifecycle support, while CD4543BNSR provides functional equivalence at the cost of mechanical incompatibility - making CD4543BM96 the recommended drop-in replacement for continuity.

Availability

CD4543BMT is available at Aetrix Electronics and suitable for industrial panel meters, appliance display modules, and legacy test equipment requiring stable component supply and long-term obsolescence management.

Supply support for CD4543BMT 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 solutions, with over 90 years of innovation in industrial, automotive, and consumer electronics.

The CD4543BMT belongs to TI's legacy 4000B-series CMOS logic family, engineered for robust, low-power digital interface functions in harsh environments - particularly display drive, address decoding, and level translation.

FAQ

What is the primary function of the CD4543BMT?

The CD4543BMT is a CMOS BCD-to-7-segment latch/decoder driver that accepts 4-bit binary-coded decimal input, stores it via an edge-triggered latch, and drives seven-segment LED displays with selectable polarity. It operates from 3 V to 18 V and supports both common-anode and common-cathode configurations via its PH pin. The CD4543BMT does not include current regulation - external resistors are mandatory per segment.

Is the CD4543BMT pin-compatible with other CD4543 variants?

Yes, the CD4543BMT shares identical pinout and electrical specifications with all CD4543B variants in SOIC-16 (D) package, including CD4543BM and CD4543BM96. Differences are limited to packaging format (tube vs. tape-and-reel), RoHS status, and moisture sensitivity level - not pin assignment or logic behavior. The CD4543BMT remains functionally interchangeable within the SOIC-16 footprint.

Does the CD4543BMT support BCD inputs above 9 (e.g., 10–15)?

No - the CD4543BMT is designed exclusively for decimal digits 0–9. Input codes 10–15 (1010–1111) produce undefined or blanked segment outputs depending on device revision and supply conditions. For hexadecimal display support, a different decoder such as the 74LS47 or custom logic is required. The CD4543BMT datasheet explicitly specifies valid operation only for BCD values 0000–1001.

Can the CD4543BMT drive LEDs directly without current-limiting resistors?

No - the CD4543BMT provides CMOS output stages without internal current limiting. Each segment output (a–g) must be connected in series with an external current-limiting resistor to prevent excessive sink/source current and potential damage. Resistor value depends on LED forward voltage, desired brightness, and supply voltage; typical values range from 220 Ω to 1 kΩ at 5 V.

What is the role of the PH (Phase) pin on the CD4543BMT?

The PH pin on the CD4543BMT selects output polarity: when PH = high, segment outputs are active-low (intended for common-anode LEDs); when PH = low, outputs are active-high (for common-cathode LEDs). This eliminates the need for external inverters or board-level redesign when changing display types. The CD4543BMT's PH pin is sampled at power-up and held static during operation unless changed externally.