MM74HC221AN

Overview

The MM74HC221AN is a dual non-retriggerable monostable multivibrator manufactured by onsemi (formerly Fairchild Semiconductor). It utilizes advanced silicon-gate CMOS technology to provide speeds comparable to low-power Schottky TTL while maintaining low power consumption and high noise immunity. The device features two independent circuits, each with negative (A) and positive (B) transition triggered inputs, as well as a clear input for resetting the one-shot. Pulse width stability is achieved using linear CMOS techniques, governed by the external timing components.

Feature Summary

• Dual non-retriggerable monostable multivibrator configuration
• Schmitt trigger inputs enable infinite signal rise or fall times
• Simple pulse width formula T = RC
• Wide power supply range from 2V to 6V

Applications

• Timing generation in digital systems
• Pulse shaping and waveform conversion
• Debouncing switches
• Frequency division

Procurement Notes

Verify that the component matches the original Fairchild Semiconductor datasheet specifications, as onsemi acquired Fairchild's logic product lines. Confirm the package type is the 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide. Ensure the part number suffix 'AN' corresponds to this specific package variant.

Selection Notes

Select this component when a dual monostable multivibrator with Schmitt trigger inputs is required. It is suitable for applications needing wide pulse ranges from 400 ns to infinity. Consider its compatibility with LS-TTL loads and its ability to operate over a wide temperature range of -40°C to +85°C.

Part Context

The MM74HC221A belongs to the 74HC series of high-speed CMOS logic devices. This series is functionally and pinout compatible with standard 74LS logic families. The 'AN' suffix specifically denotes the 16-Lead PDIP package, distinguishing it from surface-mount variants like the SOIC or SOP packages available in the same family.

Replacement Considerations

Direct substitutes include other 74HC221 variants from different manufacturers, such as SN74HC221N from Texas Instruments. Ensure any replacement maintains the dual non-retriggerable functionality and PDIP package dimensions if board space is constrained.