DM74ALS21AM Equivalent & Substitute Parts

Part Overview

The DM74ALS21AM is a 2-channel AND gate logic IC manufactured by onsemi in a 14-SOIC surface mount package. This component implements dual 4-input AND gate functions with a supply voltage range of 4.5V to 5.5V and operating temperature range of 0°C to 70°C. The part is currently listed as obsolete, making identification of equivalent and substitute components essential for design continuity and procurement planning.

Key Parameters

Parameter	Value
Logic Type	AND Gate
Number of Circuits	2
Number of Inputs	4
Voltage - Supply	4.5V ~ 5.5V
Current - Output High, Low	400µA, 8mA
Input Logic Level - Low	0.8V
Input Logic Level - High	2V
Max Propagation Delay @ V, Max CL	15ns @ 5V, 50pF
Operating Temperature	0°C ~ 70°C
Mounting Type	Surface Mount
Package / Case	14-SOIC (0.154", 3.90mm Width)
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the DM74ALS21AM is determined by strict equivalence across the following parameters: logic type (AND gate), number of circuits (2), number of inputs (4), supply voltage range (4.5V ~ 5.5V), output current specifications (400µA high, 8mA low), input logic levels (0.8V low, 2V high), propagation delay (15ns @ 5V, 50pF), and operating temperature range (0°C ~ 70°C).

The substitute parts are grouped into three categories based on packaging and product status:

Direct Manufacturer Equivalent (SN74ALS21ADR): Identical electrical parameters and 14-SOIC package footprint with active product status and tape & reel packaging.

Similar Manufacturer Part (SN74ALS21ANSR): Identical electrical parameters with 14-SO package (0.209", 5.30mm width) instead of 14-SOIC, requiring PCB footprint verification for mechanical compatibility.

Parametric Equivalent (SN74ALS21AD): Identical electrical parameters and 14-SOIC package footprint with last-time-buy product status and tube packaging.

Parameter Comparison

Parameter	DM74ALS21AM (onsemi)	SN74ALS21ADR (TI)	SN74ALS21ANSR (TI)	SN74ALS21AD (TI)
Logic Type	AND Gate	AND Gate	AND Gate	AND Gate
Number of Circuits	2	2	2	2
Number of Inputs	4	4	4	4
Voltage - Supply	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V
Current - Output High, Low	400µA, 8mA	400µA, 8mA	400µA, 8mA	400µA, 8mA
Input Logic Level - Low	0.8V	0.8V	0.8V	0.8V
Input Logic Level - High	2V	2V	2V	2V
Max Propagation Delay @ V, Max CL	15ns @ 5V, 50pF	15ns @ 5V, 50pF	15ns @ 5V, 50pF	15ns @ 5V, 50pF
Operating Temperature	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C	0°C ~ 70°C
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package / Case	14-SOIC (0.154", 3.90mm)	14-SOIC (0.154", 3.90mm)	14-SOIC (0.209", 5.30mm)	14-SOIC (0.154", 3.90mm)
Product Status	Obsolete	Active	Active	Last Time Buy
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

SN74ALS21ADR (Texas Instruments) is the primary substitute for new designs and procurement. This part maintains identical electrical parameters and package footprint (14-SOIC, 0.154" width) with active product status and ROHS3 compliance. Tape & reel packaging supports automated assembly processes.

SN74ALS21ANSR (Texas Instruments) provides electrical equivalence with a wider 14-SOIC package (0.209" width). PCB footprint compatibility must be verified before selection, as the increased package width may require layout modifications.

SN74ALS21AD (Texas Instruments) offers parametric equivalence with identical footprint but carries last-time-buy status, limiting long-term availability. This option is suitable only for legacy system maintenance or limited-quantity applications where procurement windows remain open.

All three substitutes are ROHS3 compliant and maintain MSL 1 (unlimited) moisture sensitivity ratings, ensuring compatibility with standard manufacturing and storage conditions.

Frequently Asked Questions (FAQ)

Q: Can SN74ALS21ADR be used as a direct replacement for DM74ALS21AM?

A: Yes. SN74ALS21ADR maintains identical electrical parameters, supply voltage range, output current specifications, propagation delay, and operating temperature. The 14-SOIC (0.154", 3.90mm) package footprint is mechanically compatible without PCB modifications.

Q: What is the difference between SN74ALS21ADR and SN74ALS21ANSR?

A: Both parts are electrically identical with the same logic function, input/output specifications, and propagation delay. The primary difference is package width: SN74ALS21ADR uses 14-SOIC (0.154", 3.90mm) while SN74ALS21ANSR uses 14-SOIC (0.209", 5.30mm). PCB footprint compatibility must be confirmed before substitution.

Q: Why is DM74ALS21AM listed as obsolete?

A: The DM74ALS21AM is no longer in active production by onsemi. Texas Instruments maintains active production of functionally equivalent parts in the 74ALS21 series, providing continuity for applications requiring this logic function.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. SN74ALS21ADR, SN74ALS21ANSR, and SN74ALS21AD are all ROHS3 compliant, meeting environmental and regulatory requirements for modern manufacturing and deployment.

Q: What packaging options are available for substitutes?

A: SN74ALS21ADR is supplied in tape & reel (TR) packaging for automated assembly. SN74ALS21ANSR is supplied in tape & reel (TR) packaging. SN74ALS21AD is supplied in tube packaging for manual handling and lower-volume applications.

Q: Can SN74ALS21AD be used for new production?

A: SN74ALS21AD carries last-time-buy status, indicating limited remaining availability. For new production designs, SN74ALS21ADR is the recommended choice due to active product status and continuous supply assurance.

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