onsemi MC74HCT08ADG

Overview

MC74HCT08ADG from onsemi is a quad 2-input AND gate in SOIC-14 package, operating from 2.0 V to 6.0 V, delivering 10 LSTTL load drive capability, with guaranteed propagation delay ≤19 ns at 5.0 V and input leakage ≤±1.0 µA at 125°C. It serves as a logic-level combiner in industrial control I/O conditioning circuits.

For engineers reviewing the MC74HCT08ADG datasheet, pinout, applications, or equivalent options, key selection criteria include LSTTL-compatible inputs, −55°C to +125°C operating range, SOIC-14 Pb-free packaging, and verified 4.4 V VOH at 4.5 V VCC with 4 mA load.

Technical Context

The MC74HCT08ADG implements four independent AND gates using high-performance silicon-gate CMOS technology, with inputs fully compatible with both standard CMOS and LSTTL output voltage levels. Its architecture ensures direct interfacing to TTL, NMOS, and CMOS loads without level-shifting circuitry.

It meets JEDEC Standard No. 7A for HCT logic families and supports operation across the full industrial temperature range (−55°C to +125°C) with validated DC and AC performance under all recommended conditions, including 50 pF capacitive loading and 6 ns input rise/fall times.

Key Specifications

Pinout & Package

MC74HCT08ADG is housed in a 14-lead SOIC package (Case 751A), with 1.27 mm lead pitch and Pb-free finish. Pin 14 is VCC; Pin 7 is GND.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2-input AND gate applications.

Compared with SN74HCT08DR and 74HCT08D,653, the MC74HCT08ADG uniquely supports −55°C operation and carries onsemi's full industrial qualification suite, making it the preferred choice for harsh-environment control logic where cold-start reliability and long-term parametric stability are mandatory.

Availability

MC74HCT08ADG is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, and medical diagnostic equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC74HCT08ADG 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient electronics, delivering silicon solutions for automotive, industrial, cloud, and IoT applications.

The MC74HCT08ADG belongs to onsemi's HCT logic family, engineered for seamless migration from legacy TTL systems while delivering CMOS power efficiency and noise immunity in industrial and automotive control logic.

FAQ

What is the maximum operating temperature for MC74HCT08ADG?

The MC74HCT08ADG is rated for continuous operation from −55°C to +125°C across all package types. This specification is validated per the Recommended Operating Conditions table in the official datasheet and confirmed by thermal characterization under full-load DC and AC conditions. The SOIC-14 package (MC74HCT08ADG) maintains guaranteed timing and voltage thresholds throughout this range, making it suitable for under-hood automotive and industrial edge computing applications where ambient temperatures exceed 100°C.

Does MC74HCT08ADG support 3.3 V logic systems?

Yes, MC74HCT08ADG operates reliably at 3.3 V supply (within its 2.0–6.0 V range). At VCC = 3.3 V, VIH is guaranteed ≥2.0 V and VIL ≤0.8 V, ensuring compatibility with standard 3.3 V CMOS outputs. Its LSTTL-compatible inputs accept 3.3 V logic highs without external biasing, and output VOH exceeds 3.0 V with 4 mA load - sufficient to drive downstream 3.3 V inputs with margin. Full AC performance (e.g., tPLH) is characterized down to 2.0 V, though propagation delay increases slightly versus 5 V operation.

Is MC74HCT08ADG pin-compatible with the original 74LS08?

Yes, MC74HCT08ADG is explicitly designed as a pinout-identical replacement for the 74LS08, as stated in the datasheet: "The MC74HCT08A is identical in pinout to the LS08." All 14 pins - including VCC (Pin 14), GND (Pin 7), and the four AND gate input/output pairs - match exactly. This allows direct PCB-level substitution in legacy designs, provided the system's supply voltage and temperature requirements align with the HCT family's specifications.

What is the input capacitance of MC74HCT08ADG?

The maximum input capacitance (Cin) of MC74HCT08ADG is 10 pF per input pin, as specified in the AC Characteristics table under CL = 50 pF test conditions. This value remains consistent across temperature (−55°C to +125°C) and supply voltage (4.5–5.5 V). Low input capacitance minimizes loading on upstream drivers and preserves signal integrity in high-speed or high-fanout configurations - especially important when driving multiple MC74HCT08ADG inputs from a single source.

How does MC74HCT08ADG handle unused inputs?

Unused inputs on MC74HCT08ADG must be tied to a valid logic level - either VCC or GND - and must never be left floating. The datasheet explicitly states: "Unused inputs must always be tied to an appropriate logic voltage level (e.g., either GND or VCC)." Floating inputs can cause increased ICC, erratic output behavior, or excessive power dissipation due to internal input stage metastability. For AND gates, tying unused inputs HIGH (to VCC) preserves logical identity; tying LOW forces output LOW - both are acceptable depending on functional intent.