MM74HC123ASJ

Overview

The MM74HC123ASJ is a dual retriggerable monostable multivibrator utilizing advanced silicon-gate CMOS technology. It features two independent one-shots with negative (A) and positive (B) transition triggered inputs, plus a clear input for resetting. The device operates within a wide power supply range of 2V to 6V. Pulse width is determined by external timing components using the formula PW = REXT × CEXT. It offers Schmitt trigger inputs allowing slow rise/fall times up to one second and provides propagation delays comparable to low-power Schottky TTL while maintaining CMOS noise immunity.

Feature Summary

• Dual retriggerable monostable multivibrators with independent timing circuits
• Schmitt trigger inputs on A and B channels to accommodate slow signal transitions
• Retriggerable operation allows pulse extension when triggered during active output state
• Clear input actively resets the output latch and discharges the timing capacitor

Applications

• Pulse generation and timing control in digital systems
• Debouncing mechanical switches or contacts
• Frequency division and pulse stretching applications
• Delay line circuits requiring precise timing intervals

Procurement Notes

Verify the specific ordering code MM74HC123ASJ corresponds to the 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide as defined in the datasheet. Confirm that the suffix 'SJ' indicates this specific package variant rather than tape and reel options which require an appended 'X'. Ensure compatibility with the required operating temperature range of -40°C to +85°C for your application environment.

Selection Notes

Select this component when dual independent monostable circuits are required in a single package. It is suitable for designs needing Schmitt trigger inputs to handle noisy or slow-rising signals without additional conditioning. The CMOS technology ensures low static power consumption. Verify that the external RC network can support the desired pulse width range, noting that minimum resistance values vary with supply voltage.

Part Context

This part belongs to the MM74HC123A family of dual retriggerable monostable multivibrators manufactured by Fairchild Semiconductor, now associated with onsemi. The ASJ suffix specifically denotes the 16-Lead Small Outline Package (SOP) conforming to EIAJ TYPE II standards with a 5.3mm width. Other variants in the family include SOIC, TSSOP, and PDIP packages, offering flexibility for different PCB layout requirements.

Replacement Considerations

Direct pin-compatible replacements within the same family include MM74HC123AM (SOIC), MM74HC123AMTC (TSSOP), and MM74HC123AN (PDIP). These share identical electrical characteristics and logic functions but differ only in physical package dimensions. Ensure the replacement package fits the available footprint and thermal constraints of the design.