onsemi MM74HCT14MTCX

Overview

MM74HCT14MTCX from onsemi is a hex inverting Schmitt trigger IC designed for noise-immune signal conditioning and waveform shaping in digital logic systems. It features six independent gates, 10 ns typical propagation delay at 5 V, 0.6 V typical hysteresis voltage at 4.5 V supply, and TTL/LS-compatible input thresholds - enabling reliable operation in industrial control interfaces and clock conditioning circuits.

For engineers reviewing the MM74HCT14MTCX datasheet, pinout, applications, or equivalent options, key selection criteria include Schmitt-trigger hysteresis performance, TSSOP-14 package thermal and layout constraints, 4.5–5.5 V supply compliance, and compatibility with legacy 74LS logic signal levels and fanout requirements.

Technical Context

The MM74HCT14MTCX implements six independent CMOS inverting Schmitt triggers using silicon-gate technology, delivering LS-TTL drive capability (fanout of 10) while maintaining CMOS low power consumption. Its input threshold voltages (VT+ = 1.4–2.1 V, VT− = 0.6–1.4 V) and hysteresis (0.4–1.5 V) are specified across 4.5–5.5 V supply and −40°C to +85°C operating range.

Each gate operates with guaranteed output drive strength (±4.8 mA at 5.5 V), low quiescent current (≤10 µA), and input protection via internal diode clamps to VCC and GND. The device is fully compatible with 74LS pinout and functional behavior, supporting drop-in replacement in existing designs without logic revalidation.

Key Specifications

Pinout & Package

TSSOP-14 WB package (Case 948G), 4.9 mm × 4.4 mm footprint, 0.65 mm pitch, 1.2 mm max height - optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar hex inverting Schmitt trigger applications.

Compared with SN74HCT14PWR and 74HC14DT, the MM74HCT14MTCX offers best-in-class noise immunity at 5 V with guaranteed LS-TTL compatibility and lowest quiescent current (≤10 µA), making it optimal for industrial sensor nodes requiring long-term stability and minimal power overhead.

Availability

MM74HCT14MTCX is available at Aetrix Electronics and suitable for industrial control interfaces, sensor signal conditioning, low-power oscillators, and RS-232 receiver buffering requiring stable component supply and long-lifecycle support.

Supply support for MM74HCT14MTCX 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 innovation for automotive, industrial, cloud, and IoT applications.

The MM74HCT14MTCX belongs to the 74HCT logic family, engineered specifically for seamless migration from bipolar 74LS designs into lower-power CMOS implementations while preserving pinout, timing, and interface behavior.

FAQ

What is the maximum operating temperature range for the MM74HCT14MTCX?

The MM74HCT14MTCX is rated for continuous operation from −40°C to +85°C, with all DC and AC electrical characteristics guaranteed across this full industrial temperature range. This includes hysteresis voltage, propagation delay, and output drive strength - ensuring reliable performance in factory-floor or outdoor-mounted electronics where ambient temperatures fluctuate widely. The MM74HCT14MTCX maintains its 0.4 V minimum hysteresis even at −40°C, critical for noise immunity in cold environments.

Does the MM74HCT14MTCX require external pull-up or pull-down resistors on unused inputs?

No, the MM74HCT14MTCX does not require external termination on unused inputs because each input has internal protection diodes clamped to VCC and GND, and the CMOS structure presents high impedance when floating. However, for best noise immunity and predictable logic state, onsemi recommends tying unused inputs to VCC or GND - either directly or via a resistor - to prevent unintended oscillation or increased ICC. Leaving inputs unconnected may cause erratic behavior in high-noise environments, though the MM74HCT14MTCX itself will not be damaged.

Can the MM74HCT14MTCX be used as a standalone oscillator, and what are the design constraints?

Yes, the MM74HCT14MTCX can be configured as a relaxation oscillator using a single inverter gate with external resistor and capacitor. Per the datasheet's Figure 3, the oscillation frequency depends on R, C, and the device's hysteresis (VT+ and VT−). For stable operation, R must be ≥1 kΩ to limit input current, and C should be ≥100 pF to ensure adequate timing resolution. The MM74HCT14MTCX achieves typical frequencies from 1 kHz to 1 MHz with standard components, but accuracy degrades above 500 kHz due to propagation delay variation - confirmed by AC specs showing tPHL/tPLH up to 25 ns at temperature extremes.

Is the MM74HCT14MTCX pin-compatible with the older 74LS14 in a TSSOP-14 footprint?

Yes, the MM74HCT14MTCX is functionally and pinout-compatible with the 74LS14, including identical pin assignments (inputs on odd pins 1/3/5/9/11/13, outputs on even pins 2/4/6/8/10/12, VCC on pin 14, GND on pin 7) and matching TSSOP-14 mechanical dimensions (Case 948G). This allows direct replacement in existing 74LS14-based layouts without PCB modification - provided the system operates within the MM74HCT14MTCX's 4.5–5.5 V supply range and accounts for its lower quiescent current and improved noise margin.

What is the absolute maximum rating for VCC on the MM74HCT14MTCX, and what happens if exceeded?

The absolute maximum VCC rating for the MM74HCT14MTCX is +6.5 V, as specified in the Absolute Maximum Ratings table. Exceeding this voltage - even momentarily during power-up or transient events - risks permanent damage to the internal gate oxides and input protection diodes. Operation above 5.5 V (the recommended maximum) may cause increased ICC, timing skew, or output voltage degradation before failure occurs. The MM74HCT14MTCX is not designed for 6 V battery or unregulated supply use; sustained operation above 5.5 V voids parametric guarantees and accelerates wear-out mechanisms.