onsemi MC74LCX32MELG

Overview

MC74LCX32MELG from onsemi is a low-voltage CMOS quad 2-input OR gate operating from 1.65 V to 5.5 V, featuring 5.0 V-tolerant inputs, 24 mA balanced output drive at 3.0 V, and near-zero static supply current (10 µA). It serves as a level-shifting logic buffer in mixed-voltage digital systems such as industrial I/O modules and battery-powered microcontroller peripherals.

For engineers reviewing the MC74LCX32MELG datasheet, pinout, applications, or equivalent options, key selection considerations include its 5 V-tolerant input capability, SOIC-14 package compatibility, −40 °C to +125 °C operating range, and LVTTL/LVCMOS interface compliance for legacy-to-low-voltage signal translation.

Technical Context

The MC74LCX32MELG implements four independent OR logic functions with TTL-compatible inputs and outputs, enabling direct interfacing between 3.3 V/2.5 V logic domains and 5.0 V legacy systems. Its high-impedance inputs reduce loading on upstream drivers, while its rail-to-rail output swing supports robust noise margins across supply voltages.

It operates within a wide V_CC range (1.65–5.5 V), maintains defined VIH/VIL thresholds across all supply conditions, and delivers propagation delays as low as 4.0 ns at 4.5–5.5 V - critical for timing-critical control path logic in programmable logic controllers and sensor interface circuits.

Key Specifications

Pinout & Package

MC74LCX32MELG is packaged in a 14-lead SOIC (Case 751A), with 1.27 mm pitch, Pb-free finish, and JEDEC-standard footprint. Pin 1 is marked by a beveled corner or notch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC32APWR and 74AHC32PW,118, the MC74LCX32MELG uniquely supports true 5 V-tolerant inputs at any V_CC from 1.65–5.5 V - making it the only drop-in solution for retrofitting low-voltage MCUs into legacy 5 V infrastructure without signal conditioning.

Availability

MC74LCX32MELG is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and portable medical device applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for MC74LCX32MELG 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, and medical applications.

The MC74LCX32MELG belongs to the LCX family of low-voltage CMOS logic devices designed specifically for mixed-voltage system interfacing, emphasizing 5 V-tolerant inputs, ultra-low static power, and extended temperature operation.

FAQ

What is the maximum input voltage rating for MC74LCX32MELG?

The MC74LCX32MELG supports DC input voltages from −0.5 V to +6.5 V, independent of V_CC. This 5 V-tolerant specification allows safe connection to 5.0 V TTL outputs even when powered from 1.8 V or 3.3 V supplies - a key differentiator versus standard LVC or AHC logic families. The MC74LCX32MELG datasheet confirms this in the Maximum Ratings table under VI.

Can MC74LCX32MELG operate at 1.8 V supply voltage?

Yes, the MC74LCX32MELG is fully specified for operation at 1.65 V to 5.5 V, including 1.8 V. At V_CC = 1.8 V, it delivers guaranteed VIH = 0.65 × V_CC ≈ 1.17 V and VIL = 0.35 × V_CC ≈ 0.63 V, with propagation delay <9.8 ns. The MC74LCX32MELG maintains full functionality and timing compliance across this entire range per the Recommended Operating Conditions table.

Is MC74LCX32MELG pin-compatible with standard 74HC32 or 74LS32?

No, the MC74LCX32MELG is not pin-compatible with 74HC32 or 74LS32. While all are quad 2-input OR gates in 14-pin packages, the MC74LCX32MELG uses a distinct pinout: inputs A0/B0 → pins 1/2, output O0 → pin 3; whereas 74HC32 places A0/B0 on pins 1/2 and O0 on pin 3 - same physical mapping. However, MC74LCX32MELG's GND (pin 7) and V_CC (pin 14) match industry standard, enabling PCB reuse only if layout follows SOIC-14 JEDEC outline and avoids legacy 74LS-specific routing constraints.

Does MC74LCX32MELG require external pull-up resistors on unused inputs?

Yes, unused inputs on the MC74LCX32MELG must be tied to either V_CC or GND - floating inputs are prohibited due to increased ICC and potential oscillation. The datasheet explicitly states "For ICC reasons, DO NOT FLOAT Inputs" and recommends tying unused A_n/B_n terminals to a defined logic level. This applies to all four OR gates; leaving any input unconnected risks elevated power consumption and undefined output states in the MC74LCX32MELG.

What is the thermal resistance (θ_JA) of MC74LCX32MELG in SOIC-14 package?

The MC74LCX32MELG in SOIC-14 (Case 751A) has a junction-to-ambient thermal resistance (θ_JA) of 116 °C/W under standard JEDEC test conditions (2-ounce copper, 76 mm × 114 mm board, no airflow). This value is confirmed in the Maximum Ratings table and enables reliable operation up to +125 °C ambient when power dissipation remains below 8.3 mW at 125 °C - well within typical logic usage of the MC74LCX32MELG.