Texas Instruments CD74HCT373E

Overview

CD74HCT373E from Texas Instruments is an octal transparent D-type latch with 3-state outputs, designed for bus-oriented data latching in digital systems. It operates from 4.5 V to 5.5 V, supports –55°C to 125°C temperature range, features balanced propagation delays (max 48 ns), and drives up to 10 LS-TTL loads. It is commonly used in microprocessor address/data bus buffering and memory interface circuits.

For engineers reviewing the CD74HCT373E datasheet, CD74HCT373E pinout, CD74HCT373E application, or CD74HCT373E equivalent, key selection criteria include its TTL-compatible inputs, independent output-enable control, latch-enable timing (min 16 ns pulse width), high-impedance output capability, and PDIP-20 packaging for through-hole prototyping and industrial control boards.

Technical Context

The CD74HCT373E implements eight independent D-type latches with a shared latch-enable (LE) input: when LE is high, Q outputs mirror D inputs; when LE goes low, outputs retain the last D value. Its buffered output-enable (OE) input controls all eight outputs simultaneously, placing them in high-impedance state without affecting internal latch operation.

This architecture enables bidirectional bus isolation - data can be latched while OE holds outputs high-Z, allowing concurrent bus access by other devices. The device uses HCMOS technology with TTL voltage-level compatibility, ensuring interoperability with legacy LS-TTL logic while reducing power consumption significantly.

Key Specifications

Pinout & Package

CD74HCT373E is housed in a 20-pin Plastic Dual In-line Package (PDIP-N), measuring 25.40 mm × 6.35 mm, optimized for through-hole mounting and manual prototyping.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal latch applications.

Compared with SN74HCT373N, CD74HCT373E offers identical functionality with extended temperature qualification; versus 74ACT373PC, it trades speed for ruggedness and lower static power, making it optimal for reliability-critical industrial control and aerospace subsystems.

Availability

CD74HCT373E is available at Aetrix Electronics and suitable for microprocessor bus interface, memory address latching, industrial I/O expansion, and legacy system bus isolation requiring stable component supply across extended temperature ranges.

Supply support for CD74HCT373E 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 delivering analog and embedded processing solutions, with over 90 years of innovation in logic, power management, and signal chain technologies.

The CD74HCT373E belongs to TI's HCT logic family - engineered for TTL-compatible operation with CMOS power efficiency, targeting industrial control, instrumentation, and legacy system upgrades where robustness and interoperability are essential.

FAQ

What is the maximum propagation delay of the CD74HCT373E under recommended operating conditions?

The CD74HCT373E has a maximum propagation delay (tpd) of 48 ns from D input to Q output when VCC = 4.5 V and operating across the full temperature range (–55°C to 125°C). This value is measured with a 50-pF load and defines the worst-case timing budget for synchronous latch operations in bus interface designs. The CD74HCT373E maintains consistent delay characteristics across temperature, supporting deterministic timing closure in real-time control systems.

Can the CD74HCT373E be used with a 3.3 V microcontroller interface?

No, the CD74HCT373E is not compatible with 3.3 V logic interfaces. It requires a 4.5 V to 5.5 V supply and has TTL-compatible input thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V), but its outputs swing rail-to-rail at 5 V levels. Direct connection to 3.3 V inputs risks overvoltage damage or unreliable logic interpretation. To interface with 3.3 V systems, level-shifting circuitry or a 3.3 V–compatible latch such as the SN74LVC373A must be used alongside the CD74HCT373E.

How does the output-enable (OE) function interact with the latch-enable (LE) in the CD74HCT373E?

In the CD74HCT373E, OE and LE operate independently: OE controls output driver state (active or high-Z), while LE controls data capture timing. When OE is high, all Q outputs enter high-impedance regardless of LE state or stored data; when OE is low, outputs reflect the latched value determined by LE's last transition. This allows data to be updated or retained internally while outputs remain isolated - a key capability for bus arbitration and hot-plug scenarios in the CD74HCT373E.

What is the recommended bypass capacitor for the CD74HCT373E, and where should it be placed?

Texas Instruments recommends a 0.1-μF ceramic bypass capacitor connected directly between VCC (pin 20) and GND (pin 9) of the CD74HCT373E, placed as close as physically possible to the device pins. This placement minimizes inductance and suppresses high-frequency supply noise generated during output switching. For enhanced noise immunity in noisy environments, a second 1-μF capacitor may be paralleled with the 0.1-μF unit. Proper decoupling is essential to maintain timing integrity and prevent metastability in the CD74HCT373E.

Is the CD74HCT373E suitable for automotive under-hood applications?

The CD74HCT373E is rated for –55°C to 125°C operation and meets industrial reliability standards, but it is not AEC-Q100 qualified for automotive use. While its temperature range covers typical under-hood extremes, automotive applications require additional validation including HTOL, ESD, and board-level vibration testing per AEC-Q100. For production automotive systems, TI's automotive-qualified equivalents - such as the SN74HCT373QPWRQ1 - should be selected instead of the CD74HCT373E.