MM74HC4538MX

Overview

The MM74HC4538MX is a dual retriggerable precision monostable multivibrator implemented in advanced silicon-gate CMOS technology. It features Schmitt trigger inputs for both negative (A) and positive (B) transitions, with a clear input to reset the output. The device operates within a supply voltage range of 2V to 6V and supports a typical trigger propagation delay of 32 ns. It provides a fanout of 10 LS-TTL loads and maintains low input current at 1 µA maximum. Pulse width stability is achieved using linear CMOS techniques, governed by the equation PW = 0.7(R)(C).

Feature Summary

• Dual retriggerable monostable multivibrator architecture with independent timing circuits.
• Schmitt trigger conditioning on A and B inputs allows unlimited rise and fall times.
• Retriggerable operation extends the output pulse when triggered during the timing cycle.
• Clear input forces Q output low and resets internal circuitry regardless of pulse state.

Applications

• Timing generation and pulse stretching applications.
• Debouncing mechanical switches or contacts.
• Frequency division and pulse width modulation circuits.
• Delay line implementation in digital logic systems.

Procurement Notes

Verify the specific ordering suffix 'MX' against manufacturer documentation to confirm package type and tape/reel configuration. Ensure compatibility with existing PCB footprints for the 16-lead SOIC package. Confirm that external timing components meet minimum resistance and capacitance requirements specified in the datasheet to guarantee proper circuit operation.

Selection Notes

Select this component for designs requiring precise monostable triggering with high noise immunity. The HC series offers speed comparable to low power Schottky TTL while retaining CMOS power characteristics. Consider the wide operating temperature range and pin compatibility with CD4528/CD4538 devices if migrating from older technologies.

Part Context

This device belongs to the 74HC logic family, utilizing advanced silicon-gate CMOS technology. It is functionally equivalent to other dual monostable multivibrators but optimized for higher speeds and lower power consumption. The MM74HC4538 is designed to interface directly with CMOS, NMOS, and TTL logic families, providing robust drive capabilities for standard loads.

Replacement Considerations

The MM74HC4538 is pin compatible with the CD4528 and CD4538 one-shots. Verify electrical specifications such as propagation delay and supply voltage ranges when substituting with these equivalents to ensure system performance remains within required limits.