Texas Instruments CD74HC4543E

Overview

CD74HC4543E from Texas Instruments is a high-speed CMOS BCD-to-7-segment latch/decoder/driver optimized for direct LCD segment driving, featuring active-high latch disable (LD), blanking input (BI), and phase input (PH) for AC-coupled LCD bias control; operates from 2V to 6V with -55°C to +125°C temperature range and supports 7-segment output drive with polarity inversion via PH.

For engineers reviewing the CD74HC4543E datasheet, CD74HC4543E pinout, CD74HC4543E application, or CD74HC4543E equivalent, key selection criteria include its dual-mode segment polarity control, latch-enabled BCD storage, wide supply voltage tolerance, high noise immunity (NIL/NIH = 30% at VCC = 5V), and compatibility with both LCD and current-amplified LED/gas-discharge displays.

Technical Context

The CD74HC4543E integrates latching, decoding, and driver stages in a single monolithic CMOS device. Its latch stage captures BCD inputs on rising LD edge; the decoder maps valid BCD codes (0–9) to active-high or active-low 7-segment outputs depending on PH state; BI forces all outputs low for blanking independent of latch or decode state.

Phase input (PH) toggles output polarity synchronously - when PH = HIGH, segments drive active-high (suitable for common-cathode LCDs with backplane AC); when PH = LOW, outputs invert for active-low operation. Propagation delays are tightly balanced (e.g., tPLH/tPHL ≤ 102 ns at VCC = 4.5V, CL = 50pF), ensuring minimal segment skew critical for flicker-free display updates.

Key Specifications

Pinout & Package

CD74HC4543E is housed in a 16-pin plastic dual in-line package (PDIP-N) with standard 0.3-inch body width and through-hole mounting. Pin 8 is GND; Pin 16 is VCC; pins 1–4 and 9–12 serve as BCD inputs and 7-segment outputs respectively; LD, BI, and PH are dedicated control inputs.

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 CD4543BE and SN74LS47N, the CD74HC4543E uniquely combines wide supply range, fast CMOS speed, integrated blanking/latch/phase control, and bidirectional segment drive - making it the only option supporting both modern low-power LCDs and legacy high-brightness displays within a single footprint.

Availability

CD74HC4543E is available at Aetrix Electronics and suitable for industrial HMI panels, portable test instrumentation, and automotive dashboard displays requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for CD74HC4543E 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 decades of heritage in high-reliability logic families including the 74HC series.

The CD74HC4543E belongs to TI's high-speed CMOS logic portfolio, designed specifically for display interface applications demanding latch-controlled BCD decoding, LCD-compatible AC drive, and robust operation in harsh environments.

FAQ

What is the primary function of the PH pin on the CD74HC4543E?

The PH (Phase) pin on the CD74HC4543E controls the polarity of the 7-segment outputs: when PH = HIGH, outputs are active-high (suitable for common-cathode LCDs with AC backplane); when PH = LOW, outputs invert to active-low. This feature enables direct AC-coupled LCD driving without external inverters, preventing DC bias accumulation that degrades LCD lifetime. The CD74HC4543E uses this synchronous polarity toggle to match the backplane square wave frequency.

Can the CD74HC4543E drive LEDs directly without external transistors?

The CD74HC4543E can drive low-current LEDs (≤25mA per segment) directly, but typical 7-segment LED displays require 20–100mA per segment for adequate brightness - exceeding the CD74HC4543E's ±25mA absolute maximum rating. For reliable LED operation, external NPN/PNP transistor arrays or dedicated LED drivers are recommended. The CD74HC4543E is optimized for LCDs; its segment outputs are best used as logic-level controls for higher-power stages when driving LEDs.

Does the CD74HC4543E support BCD codes beyond 0–9?

No - the CD74HC4543E decodes only valid BCD inputs (0000–1001, i.e., decimal 0–9). Inputs 1010 through 1111 (decimal 10–15) result in undefined or non-standard segment patterns, and the datasheet explicitly states "blank" behavior for invalid codes when BI = LOW. The CD74HC4543E does not implement hexadecimal decoding or error-handling for illegal BCD; system design must ensure only valid 4-bit BCD values are presented to D0–D3.

How does the LD (Latch Disable) input affect timing in the CD74HC4543E?

The LD input on the CD74HC4543E is edge-triggered: a rising edge latches the current D0–D3 BCD value into the internal register, freezing it for subsequent decoding. While LD is LOW, the latch is transparent - changes to D0–D3 propagate immediately to the decoder. Setup (tSU = 18 ns max at VCC = 6V) and hold (tH = 8 ns max) times relative to the LD rising edge must be met to avoid metastability. This behavior makes the CD74HC4543E suitable for synchronous BCD updates in microcontroller-driven displays.

Is the CD74HC4543E RoHS compliant and lead-free?

Yes - the CD74HC4543E is RoHS compliant with lead finish (NIPDAU) and meets JEDEC standards for lead-free assembly. Per TI's packaging documentation, the PDIP package carries "Yes" for RoHS and uses matte tin (NIPDAU) plating. The CD74HC4543E has no lead exemption and is rated for peak reflow temperatures appropriate for lead-free soldering processes, though its through-hole PDIP form factor is typically wave-soldered rather than reflowed.