MM74HC221AM Equivalent & Substitute Parts

Part Overview

The MM74HC221AM is a monostable multivibrator logic IC manufactured by onsemi, housed in a 16-SOIC surface mount package. This device features dual independent circuits with Schmitt trigger inputs and a propagation delay of 22 ns. The part is currently listed as obsolete, making equivalent substitutes necessary for ongoing design support and procurement.

Key Parameters

Parameter	Value
Manufacturer Part Number	MM74HC221AM
Manufacturer	onsemi
Series	74HC
Logic Type	Monostable Multivibrator
Independent Circuits	2
Schmitt Trigger Input	Yes
Propagation Delay	22 ns
Current - Output High, Low	5.2 mA, 5.2 mA
Voltage - Supply	2 V ~ 6 V
Operating Temperature	-40°C ~ 85°C
Package / Case	16-SOIC (0.154", 3.90mm Width)
Mounting Type	Surface Mount
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the MM74HC221AM is determined by the following critical parameters:

Base product number (74HC221 series compatibility)
Package type (16-SOIC surface mount)
Functional classification (monostable multivibrator with dual independent circuits)
Schmitt trigger input presence
Supply voltage range (minimum 2 V ~ 6 V overlap required)
Output current capability (minimum 5.2 mA per output)

The substitute parts listed below maintain functional equivalence within the 74HC and 74LV logic families. Propagation delay variations are acceptable as they represent performance improvements or trade-offs within the same functional category.

Parameter Comparison

Parameter	MM74HC221AM	CD74HC221M	CD74HC221M96	CD74HC221MT	SN74LV221AD
Manufacturer	onsemi	Texas Instruments	Texas Instruments	Texas Instruments	Texas Instruments
Series	74HC	74HC	74HC	74HC	74LV
Propagation Delay	22 ns	18 ns	18 ns	18 ns	13.2 ns
Current - Output High, Low	5.2 mA, 5.2 mA	5.2 mA, 5.2 mA	5.2 mA, 5.2 mA	5.2 mA, 5.2 mA	12 mA, 12 mA
Voltage - Supply	2 V ~ 6 V	2 V ~ 6 V	2 V ~ 6 V	2 V ~ 6 V	2 V ~ 5.5 V
Operating Temperature	-40°C ~ 85°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-40°C ~ 85°C
Package / Case	16-SOIC	16-SOIC	16-SOIC	16-SOIC	16-SOIC
Product Status	Obsolete	Discontinued at DiGi Electronics	Active	Active	Discontinued at DiGi Electronics
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For designs currently using the MM74HC221AM, the following selection criteria apply:

Primary Recommendation: CD74HC221M96

This part maintains full functional compatibility with the MM74HC221AM within the 74HC logic family. It is actively manufactured and stocked, ensuring long-term availability. The CD74HC221M96 offers improved propagation delay (18 ns versus 22 ns) and extended operating temperature range (-55°C ~ 125°C). RoHS3 compliance and unlimited moisture sensitivity level (MSL 1) support modern manufacturing and environmental standards.

Secondary Recommendation: CD74HC221MT

Functionally identical to CD74HC221M96 with active product status. Packaging is supplied as Cut Tape (CT), suitable for automated assembly processes. This part is appropriate when tape packaging is preferred over reel format.

Alternative for Enhanced Performance: SN74LV221AD

The SN74LV221AD operates within the 74LV logic family and delivers superior propagation delay (13.2 ns) and higher output current capability (12 mA). However, the maximum supply voltage is limited to 5.5 V compared to 6 V for 74HC variants. This part is suitable for designs requiring faster switching performance within the 2 V ~ 5.5 V supply range. Product status is discontinued at DiGi Electronics.

Not Recommended: CD74HC221M

Although functionally compatible, this part is discontinued at DiGi Electronics, limiting procurement viability for new designs.

Frequently Asked Questions (FAQ)

Q: Can the CD74HC221M96 directly replace the MM74HC221AM without circuit modifications?

A: Yes. Both parts share the same 16-SOIC package, pinout, and functional specifications (dual monostable multivibrator with Schmitt trigger inputs). The improved propagation delay of CD74HC221M96 (18 ns versus 22 ns) represents faster operation and does not require design changes.

Q: What is the difference between CD74HC221M, CD74HC221M96, and CD74HC221MT?

A: All three are Texas Instruments 74HC221 monostable multivibrators with identical electrical specifications. The differences are packaging format: CD74HC221M is supplied in Tube, CD74HC221M96 in Cut Tape (CT) & Digi-Reel, and CD74HC221MT in Cut Tape (CT). CD74HC221M96 is the only actively manufactured variant.

Q: Is the SN74LV221AD a suitable substitute for the MM74HC221AM?

A: The SN74LV221AD is functionally compatible but operates within different electrical parameters. It supports supply voltages of 2 V ~ 5.5 V (versus 2 V ~ 6 V for 74HC variants) and delivers higher output current (12 mA versus 5.2 mA). Use this part only if your design operates within the 2 V ~ 5.5 V range and benefits from faster propagation delay (13.2 ns).

Q: Does the extended operating temperature range of CD74HC221M96 affect compatibility?

A: No. The extended range (-55°C ~ 125°C versus -40°C ~ 85°C) is a superset of the original specification. Designs operating within the original temperature range remain fully compatible.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. CD74HC221M, CD74HC221M96, CD74HC221MT, and SN74LV221AD are all RoHS3 compliant. The original MM74HC221AM RoHS status was not specified in the available data.

Q: Which substitute part offers the best long-term availability?

A: CD74HC221M96 is the recommended choice for long-term availability. It maintains active product status with the highest inventory level (19,622 pcs) and is supplied in standard Cut Tape & Digi-Reel format suitable for high-volume manufacturing.

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