SN74HC21D Equivalent & Substitute Parts

Part Overview

The SN74HC21D is a dual 4-input AND gate logic IC manufactured by Texas Instruments in a 14-SOIC surface mount package. This component is discontinued at DiGi Electronics but remains available through alternative sources. The part operates across a 2V to 6V supply voltage range and is designed for general-purpose logic applications requiring AND gate functionality with two independent channels.

Due to the discontinued status of the SN74HC21D at primary distributors, equivalent and substitute parts are necessary to maintain design continuity and ensure component availability for production and repair applications.

Substiute Parts

SN74HC21D

Texas InstrumentsIn Stock: 10684SN74HC21D Datasheet

Current PartRFQ

SN74HC21DR

Texas InstrumentsIn Stock: 3655SN74HC21DR Datasheet

DirectRFQ

74HC21D,653

Nexperia USA Inc.In Stock: 2026674HC21D,653 Datasheet

UpgradeRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the SN74HC21D are qualified based on the following criteria:

Electrical Compatibility:

• Identical logic type (AND Gate)
• Matching number of circuits (2) and inputs (4)
• Identical supply voltage range (2V ~ 6V)
• Matching quiescent current specification (2 µA max)
• Identical output current ratings (5.2mA high and low)
• Matching input logic level thresholds
• Equivalent propagation delay performance (19ns @ 6V, 50pF)

Mechanical Compatibility:

• Surface mount mounting type
• 14-pin SOIC package footprint (0.154", 3.90mm width)

Compliance & Status:

• ROHS3 compliance maintained
• MSL Level 1 rating
• Active product status preferred for long-term availability

Parameter Comparison

Engineering Selection Recommendations

SN74HC21DR (Direct Substitute): The SN74HC21DR is the primary equivalent for the SN74HC21D. Both are manufactured by Texas Instruments and share identical electrical specifications and package dimensions. The SN74HC21DR maintains active product status and is available in cut tape and Digi-Reel packaging formats. This part is suitable for direct replacement in all applications where the original SN74HC21D was specified.

74HC21D,653 (Upgrade Alternative): The 74HC21D,653 manufactured by Nexperia USA Inc. provides an alternative source for the 74HC dual 4-input AND gate function. This part maintains all critical electrical parameters and package compatibility. The extended operating temperature range (-40°C ~ 125°C) offers enhanced thermal performance compared to the original specification (-40°C ~ 85°C). The Nexperia part is available in tape and reel packaging and maintains active product status. Selection of this part is appropriate when extended temperature operation is beneficial or when supply chain diversification is required.

Both substitute parts maintain ROHS3 compliance and MSL Level 1 ratings, ensuring compatibility with standard manufacturing and storage requirements.

Frequently Asked Questions (FAQ)

Q: Can the SN74HC21DR be used as a direct replacement for the SN74HC21D?

A: Yes. The SN74HC21DR is electrically and mechanically identical to the SN74HC21D. Both parts share the same logic function, electrical specifications, and 14-SOIC package footprint. The primary difference is packaging format and product status; the SN74HC21DR is actively manufactured.

Q: What is the difference between the SN74HC21DR and the 74HC21D,653?

A: Both parts are functionally equivalent AND gates with identical electrical specifications and package dimensions. The key differences are manufacturer (Texas Instruments vs. Nexperia USA Inc.) and operating temperature range. The 74HC21D,653 supports operation to 125°C, while the SN74HC21DR is rated to 85°C. Both are ROHS3 compliant and actively produced.

Q: Are there any package compatibility concerns when substituting these parts?

A: No. All three parts use the 14-SOIC surface mount package with identical 0.154" (3.90mm) width. PCB footprints and reflow profiles are compatible across all substitutes.

Q: Which substitute part should I select for new designs?

A: For new designs, either the SN74HC21DR or 74HC21D,653 are appropriate. The SN74HC21DR maintains the original Texas Instruments source. The 74HC21D,653 offers extended temperature operation and supply chain diversity. Selection depends on thermal requirements and preferred manufacturer.

Q: Do these parts require different handling or storage procedures?

A: No. All parts share MSL Level 1 (Unlimited) moisture sensitivity rating, indicating no special moisture control requirements during storage or handling.

Q: Are the electrical characteristics identical across all three parts?

A: Yes. Supply voltage range, quiescent current, output current, input logic levels, and propagation delay are identical across the SN74HC21D, SN74HC21DR, and 74HC21D,653.