Texas Instruments CD74HC243EE4

Overview

CD74HC243EE4 from Texas Instruments is a high-speed CMOS quad-bus transceiver with three-state outputs, designed for bidirectional asynchronous data bus communication between two 4-bit buses. It supports 2 V to 6 V supply operation, delivers 7 ns typical propagation delay (VCC = 5 V, CL = 15 pF), and drives up to 15 LSTTL loads. It operates across -55°C to 125°C and features buffered inputs with high noise immunity (NIL/NIL = 30% of VCC at 5 V).

For engineers reviewing the CD74HC243EE4 datasheet, CD74HC243EE4 pinout, CD74HC243EE4 application, or CD74HC243EE4 equivalent, this device is selected for robust, low-power bidirectional bus interfacing in industrial control systems, legacy bus extenders, and mixed-voltage logic level translation where precise direction control and high-impedance isolation are required.

Technical Context

The CD74HC243EE4 implements four independent noninverting bidirectional channels, each controlled by shared OEA and OEB enable/direction inputs. Its silicon-gate CMOS architecture enables TTL-compatible drive strength while maintaining CMOS power efficiency - ICC ≤ 160 µA over full temperature range at VCC = 6 V.

Directional flow (A-to-B or B-to-A) and three-state output activation are jointly determined by the logic states of OEA and OEB per the truth table: only when OEA = L and OEB = L does data pass A→B; when OEA = H and OEB = H, it passes B→A; all other combinations force both ports into high-impedance mode.

Key Specifications

Pinout & Package

CD74HC243EE4 is housed in a 14-pin plastic dual in-line package (PDIP-N), with nominal body dimensions of 19.31 mm × 6.35 mm and 2.54 mm lead pitch. The package is RoHS-compliant with NiPdAu lead finish and rated for through-hole mounting.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad-bus transceiver applications.

Compared with CD74HC243EE4, SN74LVC243APWR offers superior speed and density but sacrifices voltage flexibility, while CD74HCT243E ensures seamless TTL integration at the cost of wider supply constraints and higher quiescent power - making CD74HC243EE4 the optimal choice for mixed-voltage, wide-temperature, and industrial-grade bus extension.

Availability

CD74HC243EE4 is available at Aetrix Electronics and suitable for industrial control systems, legacy equipment upgrades, and mixed-voltage embedded interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC243EE4 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 and industrial-grade IC design.

CD74HC243EE4 belongs to TI's CDx4HC logic series, engineered for robust bidirectional bus interfacing in harsh environments - emphasizing wide temperature operation, noise resilience, and compatibility across legacy and modern logic families.

FAQ

What is the maximum clock/data rate supported by CD74HC243EE4?

The CD74HC243EE4 is not a clocked device but a combinational transceiver; its usable data rate depends on propagation delay and bus loading. With 7 ns typical t_pd and 15 LSTTL load drive capability, it supports reliable asynchronous bus transfers up to approximately 50 MHz in well-terminated 50 pF-load systems. Actual timing must be verified using worst-case 27 ns max t_pd and system-specific trace capacitance for setup/hold compliance.

Can CD74HC243EE4 operate at 3.3 V supply voltage?

Yes, CD74HC243EE4 is fully specified for 2 V to 6 V operation, including 3.3 V. At VCC = 3.3 V, VIH = 2.31 V (min), VIL = 0.99 V (max), VOH ≥ 3.2 V (IOH = –20 µA), and VOL ≤ 0.1 V (IOL = 20 µA), ensuring clean interfacing with standard 3.3 V logic families without level shifters.

How do OEA and OEB control direction and three-state behavior in CD74HC243EE4?

In CD74HC243EE4, OEA and OEB are active-low controls: when OEA = L and OEB = H, data flows A→B; when OEA = H and OEB = L, data flows B→A; when both are H, all outputs enter high-impedance; when both are L, the device enters undefined state and must be avoided. This dual-control scheme eliminates bus contention during direction changes.

Is CD74HC243EE4 pin-compatible with CD74HCT243E?

Yes, CD74HC243EE4 and CD74HCT243E share identical PDIP-14 packaging, pinout, and functional block diagram. They differ only in input threshold specifications (HC: CMOS-compatible; HCT: TTL-compatible) and supply voltage range (HC: 2–6 V; HCT: 4.5–5.5 V), making them drop-in replacements where voltage and input logic family match.

What thermal considerations apply to CD74HC243EE4 in continuous operation?

CD74HC243EE4 has a junction-to-ambient thermal resistance (R_θJA) of 80°C/W in PDIP package. At max ICC = 160 µA and worst-case 6 V supply, static power is <1 mW - negligible heating. However, dynamic power scales with frequency and load capacitance; for high-frequency use (>10 MHz), ensure adequate PCB copper area and airflow to maintain TJ < 125°C under full bus loading.