Texas Instruments CD74HCT356E

Overview

CD74HCT356E from Texas Instruments is an 8-input high-speed CMOS multiplexer/register with edge-triggered D-type flip-flops, transparent latches, and three-state complementary outputs. It operates from 4.5V to 5.5V, supports -55°C to +125°C industrial/military temperature range, delivers 22ns typical clock-to-output propagation delay (CL = 15pF), and drives up to 15 LSTTL loads-enabling robust bus-oriented data routing in synchronous digital systems.

For engineers reviewing the CD74HCT356E datasheet, CD74HCT356E pinout, CD74HCT356E application, or CD74HCT356E equivalent, this device serves as a register-controlled 8:1 data selector with independent output-enable logic, latch/clock dual-mode input capture, and true complementary three-state outputs-critical for bidirectional bus arbitration, address/data staging, and timing-critical state-holding in legacy TTL-compatible control logic.

Technical Context

The CD74HCT356E integrates two parallel functional blocks: an 8:1 address-decoded multiplexer feeding into a bank of eight edge-triggered D flip-flops, and a separate transparent latch stage controlled by LE. Data selection (S0–S2) and latch enable (LE) operate asynchronously, while register update occurs only on low-to-high CP transitions-ensuring deterministic setup/hold timing (min 5ns setup, 9ns hold at 25°C).

Three independent output-enable inputs (OE1, OE2, OE3) control complementary Y/Y outputs in 3-state mode, supporting wired-OR bus configurations and dynamic bus direction switching. All inputs are TTL- and CMOS-compatible (VIH ≥ 2V, VIL ≤ 0.8V, II ≤ 1µA), and outputs drive both standard (10 LSTTL) and bus-driver (15 LSTTL) loads with balanced rise/fall times (12–18ns typical).

Key Specifications

Pinout & Package

CD74HCT356E is housed in a 20-lead plastic dual in-line package (PDIP-N), with 0.300-inch body width and through-hole mounting. Pin spacing is 0.100 inch, and thermal resistance θJA is 69°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-input multiplexer/register applications.

Compared with SN74HCT356N and MC74HCT356NG, the CD74HCT356E offers identical functionality and pinout but maintains legacy Texas Instruments part numbering and qualification history-making it preferred for aerospace programs requiring original TI documentation and lot traceability.

Availability

CD74HCT356E is available at Aetrix Electronics and suitable for industrial PLC I/O staging, aerospace avionics data multiplexing, and military communications control logic requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CD74HCT356E 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 founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial, automotive, and defense qualifications.

The CD74HCT356E belongs to TI's High-Speed CMOS Logic (HCT) family, designed specifically to replace bipolar TTL in legacy systems while delivering CMOS power efficiency, extended temperature operation, and direct input compatibility.

FAQ

What is the maximum clock frequency supported by the CD74HCT356E?

The CD74HCT356E does not specify a maximum clock frequency in its datasheet, but its 22ns typical clock-to-output propagation delay (CL = 15pF, VCC = 5V) implies reliable operation up to approximately 25MHz under ideal loading conditions. For sustained operation, design margins should account for worst-case delays of 77ns (CL = 50pF, -55°C to +125°C), limiting practical use to ≤10MHz in thermally demanding environments. Always validate timing with actual board-level load capacitance and temperature profiling.

Does the CD74HCT356E support both latch and register modes simultaneously?

No-the CD74HCT356E supports latch and register modes in mutually exclusive operation. When LE is low, the S0–S2 select lines and D0–D7 data are captured transparently into latches; when LE is high, the device ignores new select/data changes and only updates the output register on low-to-high CP transitions. The two paths share the same output stage but cannot hold independent values-latch mode bypasses the flip-flop entirely.

Can the CD74HCT356E drive a 50pF load reliably across its full temperature range?

Yes-the CD74HCT356E is characterized for CL = 50pF across -55°C to +125°C, with specified propagation delays up to 77ns (CP→Y) and output transition times up to 18ns. Its 15 LSTTL load drive capability (equivalent to ~45pF) exceeds 50pF under typical conditions, and the datasheet confirms performance at that load in both AC and switching specifications tables. Ensure proper VCC decoupling and minimize trace inductance for stable edge integrity.

How do the three output-enable inputs (OE1, OE2, OE3) interact in the CD74HCT356E?

All three OE inputs (OE1, OE2, OE3) must be logic low to enable the complementary Y/Y outputs; any one held high forces both outputs into high-impedance (Z) state. They are logically ANDed internally-no priority encoding or partial enable capability exists. This design allows external logic to gate the outputs using independent control signals (e.g., OE1 for CPU access, OE2 for DMA, OE3 for debug port), enhancing system-level bus arbitration flexibility.

Is the CD74HCT356E RoHS compliant and lead-free?

Yes-the CD74HCT356E is RoHS compliant with lead-free (NIPDAU) terminal finish, as confirmed in TI's official packaging addendum. It meets EU Directive 2011/65/EU requirements and carries no exemptions. The device is rated for lead-free reflow (peak 260°C per JEDEC J-STD-020), and its PDIP package has no moisture sensitivity level (MSL) rating due to its through-hole construction and inherent robustness against popcorning.