CD74AC646M Equivalent & Substitute Parts

Part Overview

The CD74AC646M is a non-inverting transceiver logic integrated circuit manufactured by Texas Instruments in the 74AC series. This device functions as a single-element, 8-bit transceiver with 3-state output capability, designed for digital signal transmission and reception applications. The CD74AC646M is classified as Last Time Buy, indicating discontinued production. Identifying equivalent and substitute parts is necessary to maintain design continuity and ensure component availability for new production runs and field replacements.

Substiute Parts

CD74AC646M

Texas InstrumentsIn Stock: 1382CD74AC646M Datasheet

Current PartRFQ

CD74AC646M96

Texas InstrumentsIn Stock: 2780CD74AC646M96 Datasheet

MFR RecommendedRFQ

MC74AC646DWG

onsemiIn Stock: 2069MC74AC646DWG Datasheet

MFR RecommendedRFQ

MC74AC646DWR2G

onsemiIn Stock: 22179MC74AC646DWR2G Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the CD74AC646M are determined by strict equivalence in the following critical parameters:

• Logic Type: Transceiver, Non-Inverting
• Number of Elements: 1
• Number of Bits per Element: 8
• Output Type: 3-State
• Output Current Capability: 24mA, 24mA
• Package / Case: 24-SOIC (0.295", 7.50mm Width)
• Mounting Type: Surface Mount
• Base Product Number: 74AC646

Substitutes are grouped into two categories based on voltage supply range compatibility:

Category A - Full Voltage Range Compatibility (1.5V ~ 5.5V): CD74AC646M96 (Texas Instruments, Tape & Reel packaging) maintains identical electrical specifications and extended voltage range support.

Category B - Reduced Voltage Range Compatibility (2V ~ 6V): MC74AC646DWG and MC74AC646DWR2G (onsemi) provide functional equivalence with a narrower lower voltage limit (2V minimum instead of 1.5V) and different operating temperature range (-40°C ~ 85°C instead of -55°C ~ 125°C).

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: CD74AC646M96

CD74AC646M96 is the recommended substitute for new designs and production. This part is manufactured by Texas Instruments (original manufacturer), maintains Active product status, and provides identical electrical specifications including the full voltage supply range (1.5V ~ 5.5V) and extended operating temperature range (-55°C ~ 125°C). The only difference is packaging format (Tape & Reel instead of Tube), which is a procurement consideration rather than a functional limitation. MSL rating of 1 (Unlimited) matches the original part.

Secondary Substitutes: MC74AC646DWG and MC74AC646DWR2G

The onsemi alternatives (MC74AC646DWG and MC74AC646DWR2G) provide functional equivalence with the following constraints:

• Voltage supply range is reduced to 2V ~ 6V, which excludes operation below 2V
• Operating temperature range is narrower (-40°C ~ 85°C), which excludes operation below -40°C and above 85°C
• Both parts carry Obsolete product status
• MSL rating is 3 (168 Hours), requiring controlled storage conditions

These parts are suitable only for applications where the reduced voltage and temperature ranges are acceptable. MC74AC646DWR2G offers higher inventory availability (22,080 pcs) compared to MC74AC646DWG (1,980 pcs).

Frequently Asked Questions (FAQ)

Q: Can CD74AC646M96 be used as a direct replacement for CD74AC646M?

A: Yes. CD74AC646M96 is functionally equivalent with identical electrical specifications. The difference is packaging format (Tape & Reel versus Tube). Both are 24-SOIC surface mount packages with the same pinout and electrical performance.

Q: What are the limitations of using MC74AC646DWG or MC74AC646DWR2G?

A: These onsemi parts have a reduced voltage supply range (2V ~ 6V minimum versus 1.5V ~ 5.5V) and narrower operating temperature range (-40°C ~ 85°C versus -55°C ~ 125°C). They are suitable only for applications operating within these narrower specifications. Both parts are Obsolete.

Q: Why is the CD74AC646M classified as Last Time Buy?

A: Last Time Buy status indicates that Texas Instruments has discontinued production. CD74AC646M96 is the recommended alternative, as it is the same base product (74AC646) in Active status with identical specifications but different packaging.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed parts (CD74AC646M, CD74AC646M96, MC74AC646DWG, and MC74AC646DWR2G) are ROHS3 Compliant.

Q: What is the difference between Tube, Tape & Reel, and Cut Tape packaging?

A: These are procurement and handling formats. Tube packaging contains loose components in a plastic tube. Tape & Reel (TR) packaging provides components on a continuous reel for automated assembly. Cut Tape (CT) packaging provides components on tape segments. All three formats contain the same 24-SOIC component with identical electrical performance.

Q: Does MSL rating affect component functionality?

A: No. MSL (Moisture Sensitivity Level) rating affects storage and handling requirements, not electrical performance. MSL 1 (Unlimited) allows indefinite storage without moisture control. MSL 3 (168 Hours) requires controlled storage conditions and baking procedures if moisture absorption limits are exceeded. This is a supply chain and manufacturing consideration.

Q: Can I use MC74AC646DWR2G in a design requiring -55°C operation?

A: No. MC74AC646DWR2G has a minimum operating temperature of -40°C. For applications requiring -55°C operation, use CD74AC646M or CD74AC646M96.